Dissertations / Theses on the topic 'Vineyards'

Thesis (MscAgric (Viticulture and Oenology))--University of Stellenbosch, 2009.
ENGLISH ABSTRACT: Little scientific information regarding the effect of different geological parent materials on grapevine performance is currently available in South Africa. This aspect is of special significance for the Helderberg area, where parent material may change from granite to shale over a short distance. This results in shale- as well as granite-derived soils often occurring within the same vineyard. The objectives of this study were to (i) quantify the nutritional status and other soil properties of different parent materials (shale and granite) and overlying soils (ii) investigate the impact of geological differences in the soil on the vine nutritional status and certain vine parameters. This study was done over two seasons (2006/2007 and 2007/2008). Two Sauvignon blanc and two Cabernet Sauvignon vineyard blocks were selected at two different localities for each cultivar in the Helderberg area, South Africa. Shale- and granitederived soils were identified within each block. Kaolinite was the dominant mineral, whereas quartz and feldspar were sub-dominant. Traces of mica were also present in some shale- and granite-derived soils. Granite- contained significantly higher contents of coarse sand than shale-derived soils, whilst the opposite occurred in terms of fine sand. These differences affected the water holding capacity, in general making it higher in shale- than granite-derived soils. Shale-derived soils had higher concentrations of total K but granite-derived soils had a higher ability to release K as they contained higher concentrations of soluble K. The Q/I parameters, potential buffering capacity of K (PBCK) and equilibrium activity ratio of K (ARK) showed no consistent responses to geological differences. Potassium concentrations were higher in the leaf blades (obtained before harvest in 2007) from Sauvignon blanc grapevines on granite- than on shale-derived soils. Potassium concentrations in the Cabernet Sauvignon juice (obtained in 2007) tended higher in juice from granite- than from shale-derived soils. In 2008, K concentrations tended higher in juice from shale- than from granite-derived soils for both cultivars. The pH of the Sauvignon blanc juice (obtained in 2008) tended higher in juice from shale-than from granite-derived soils, thus corresponding with the K concentrations in the juice in this season. Nitrogen concentrations were higher in Cabernet Sauvignon juice (obtained in 2007) and Sauvignon blanc juice (obtained in 2008) from shalethan from granite-derived soils. In terms of vine water status, vines on granite-derived soils appeared more stressed than those on shale-derived soils in both seasons at one of the vineyards. In these Sauvignon blanc and Cabernet Sauvignon vineyards, the K nutritional status was not affected by geology in a consistent manner but there were some noticeable tendencies for a specific cultivar during certain seasons. On account of vines being planted on shale- and granite-derived soils within the same block, soil preparation was done similarly for both soils, and they were exposed to similar irrigation schedules, canopy management strategies and climatic conditions. Therefore, there is a high probability that all these practices may have negated the effect of geology on the K status of soils and especially on juice K concentration at the time of harvest. It was clear that seasonal differences and fertilisation affected the nutritional status of the vines more than geology.
AFRIKAANSE OPSOMMING: In Suid-Afrika is daar tans min wetenskaplike inligting oor die effek van verskillende geologiese moedermateriale op die prestasie van wingerd beskikbaar. Hierdie aspek is veral van belang in die Helderberg-area, waar moedermateriaal oor ‘n baie kort afstand van graniet na skalie kan wissel. Dit lei daartoe dat skalie-, sowel as granietgronde, dikwels binne dieselfde wingerd voorkom. Die doelwitte van die studie was om: (i) die voedingstatus en ander grondkundige eienskappe van die verskillende moedermateriale (skalie en graniet) en oorliggende gronde te kwantifiseer (ii) die impak van geologiese verskille in die grond op wingerd se voedingstatus en sekere wingerdkundige parameters, te ondersoek. Hierdie studie is oor twee seisoene (2006/2007 en 2007/2008) gedoen. Twee Sauvignon blanc en twee Cabernet Sauvignon wingerdblokke is geselekteer by twee verskillende lokaliteite vir elke kultivar in die Helderbergarea, Suid-Afrika. Beide skalie- en granietgrond is binne elke blok geïdentifiseer. Kaoliniet was die dominante mineraal, met kwarts en veldspaat sub-dominant, terwyl spore van mika ook in beide skalie- en granietgronde gevind is. Granietgronde het betekenisvol hoër hoeveelhede growwe sand bevat, terwyl skaliegronde meer fyn sand bevat het. Hierdie verskille het ‘n effek op waterhouvermoë gehad en daartoe gelei dat waterinhoude oor die algemeen hoër was vir skaliegronde. Skaliegronde het groter hoeveelhede totale K bevat, maar granietgronde se vermoë om K vry te stel was hoër, omdat hulle ‘n hoër konsentrasie oplosbare K bevat het. Die Q/I parameters, potensiële buffervermoë vir K (PBCK) en ewewig aktiwiteitsverhouding vir K (ARK), is nie op ‘n konsekwente wyse deur geologiese verskille beïnvloed nie. Vir die Sauvignon blanc wingerde was kalium konsentrasies in blaarskywe (gemonster voor oes in 2007) hoër vir graniet- as vir skaliegronde. Kalium konsentrasies in die sap vanaf Cabernet Sauvignon (gemonster in 2007) het hoër geneig vir granietgronde. In 2008 het die kalium konsentrasies, vir beide kultivars, hoër geneig in sap vanaf skaliegronde. Gedurende dié seisoen het die pH van sap ook hoër geneig vir Sauvignon blanc vanaf skaliegronde, wat dus ooreenstem met die K inhoud van die sap. Stikstof konsentrasies was hoër in sap vanaf skaliegronde vir Cabernet Sauvignon (2007) en vir Sauvignon blanc (2008). In terme van die wingerde se waterstatus, het stokke op die granietgrond, by een van die lokaliteite, geneig om gedurende beide seisoene onder groter stremming te wees op graniet as op skaliegrond. In hierdie Sauvignon blanc en Cabernet Sauvignon wingerde, is K voedingstatus nie op ‘n konsekwente wyse deur geologie geaffekteer nie, maar gedurende sommige seisoene was daar wel duidelike tendense vir ‘n spesifieke kultivar. Omdat die stokke binne dieselfde blok op skalie- en graniet gronde geplant is, was grondvoorbereiding eenders vir die twee grondtipes terwyl besproeiingskedule, lowerbestuur en klimaatstoestande ook identies was. Daar is dus ‘n hoë waarskynlikheid dat al hierdie faktore daartoe kon bygedra het dat die effek van geologie op die K status van van gronde versluier is, veral die effek op die K inhoud van sap teen oestyd. Dit was duidelik dat seisoenale klimaatsverskile en bemestingspraktyke ’n groter effek as geologie op die voedingstatus van die wingerd gehad het.

Pierceâ s disease (PD) is a vascular disease of grapevines caused by Xylella fastidiosa (Wells et al.) (Xf) which is transmitted by xylophagous insect vectors. PD infection in Virginia vineyards was thought to be isolated to southeastern portions of the state as there have been no reports of vine loss in western Virginia and cold winter temperatures experienced there limit the effects of the bacterium from year to year. Upward trends in winter temperatures have raised PD concern in the mid-Atlantic. My risk assessment study found PD symptomatic vines beyond the modeled boundary for infection, confirmed Xf-positive with DAS-ELISA. Yellow sticky traps were used to survey Virginia vineyards throughout the 2006 and 2007 growing seasons to identify sharpshooter (Cicadellinae) species in six growing regions. Graphocephala versuta (Say) and Oncometopia orbona (Fabricius) (Hemiptera: Cicadellidae) were trapped in the greatest abundance and were both present in every region surveyed. This study uses geographical representation of climatological data to estimate risk for Pierce's disease.
Master of Science in Life Sciences

Vineyards in the Eastern United States are often prone to excessive vegetative growth. In order to suppress excessive vine vigor, many viticulturists have employed cover cropping strategies. Cover crops provide a myriad of agronomic benefits, however they are known to compete with the vine for water and nutrients. Due to the widespread use of cover crops in Eastern vineyards, many vineyards experience nitrogen (N) deficiencies in both the vegetative vine tissue and yeast assimilable nitrogen (YAN) in the juice. Soil applications of calcium nitrate and foliar applications of urea were assessed as a means of vineyard N amelioration at cover cropped sites comprised of Petit Manseng and Sauvignon blanc (Vitis vinifera L.). Perennial White and Crimson clover cover crops and foliar urea applications were also used in a Vidal blanc (Vitis spp.) vineyard. Treatments were imposed in the Sauvignon blanc vineyard for five years. The Petit Manseng and Vidal blanc vineyards were subjected to treatments for two years. Soil-applied N at bloom was most effective at increasing leaf petiole N at véraison, season-long chlorophyll content index (CCI), vine capacity and fruit yield. Fruit yield was increased due to more berries per cluster and greater berry weights. Increased rates of soil-applied N decreased the fruit weight:pruning weight ratio. Foliar-applied N after fruit set was most effective at increasing berry YAN. While most of the measured amino acids in fruit increased in concentration with the application of either soil or foliar N, foliar applications were more effective at increasing fruit amino acids. Clover cover crops offered little to no benefit as a N source in the two-year period of evaluation. None of the N management schemes negatively impacted canopy density, fruit zone light interception, or botrytis bunch rot incidence. The combination of both a soil-applied and foliar-applied N fertilizer may be the most effective means to increase both vine capacity and YAN in vineyards where vineyard floor cover crops are compromising vine N status.
Master of Science

The fermentation of grape must by the action of microbial species naturalised within the vineyard and/or winery environment, rather than the use of monoculture inoculation, is practiced within some sections of the wine industry. From a technological perspective this represents a retrograde step, and is driven by actual or perceived consumer demands for culturally and ethically responsible food products, and unique products with optimal and diversified sensory complexity. The vineyard environment houses a complex microbiota, potentially including naturalised yeast genotypes. The aim of this thesis is to identify the diversity of the naturalised yeast population in Margaret River vineyards, targeting the Saccharomycotina sub-phylum. In addition, it aims to improve existing methods for their identification and characterisation, and discuss the potential oenological implications of these species, and their role in naturalised fermentation. A diverse microbiota of fungal species capable of fermentation was identified within grape-derived samples sourced from Margaret River vineyards. The potential for pleasant and complex (from a sensory perspective) wines to be produced by these species is highlighted.However, the limits of current knowledge indicate there is still future research to be conducted. The application of appropriate barcodes for the culture-independent amplification of fungal species capable of fermentation was elucidated, and reinforces the validity of a two-gene approach. In addition, the modification of an appropriate plating regime for the application of culture-dependent analyses can now reduce the risk of cultivation bias in qualitative mucosal colony isolation from grape samples. The aims of this thesis were addressed in full, and the application of naturalised fermentation utilising diverse yeast populations naturalised in Margaret River vineyards, evaluated.

To determine the Botryosphaeria species involved in grapevine decline in Western Australia a survey was conducted on five grape growing regions, Swan District, Margaret River, Manjimup, Pemberton and Geographe. Sixteen vineyards were sampled for symptoms including bleached canes, vines with limited or no bud burst and wedge and half moon shaped internal lesions. Four Botryosphaeria species, B. obtusa, B. australis, B. rhodina and B. stevensii were found to be associated with grapevine decline in Western Australia. This is the first recording of B. australis and B. stevensii associated with grapevines in Western Australia. Botryosphaeria species are widespread on Western Australia grapevines with a total of 62.5% of the vineyards having at least one Botryosphaeria species isolated. Of the Botryosphaeria species, B. obtusa was the most commonly isolated, with 51 isolates from 6 vineyards, followed by B. australis with 37 isolates from 8 vineyards, B. rhodina with 3 isolates from 2 vineyards and a single isolate of B. stevensii from vineyard 13. Identifying the Botryosphaeria isolates to species level was difficult based on morphological characteristics. Colony morphology was often found to look similar and had an ability to change on different substrates, while the conidia of several species were also similar in shape, size and pigmentation. Combining the morphological characteristics with DNA sequencing techniques provided an accurate and reliable form of identification. Botryosphaeria australis was characterised by the production of a yellow pigment in culture. B. obtusa and B. stevensii both produce brown conidia with septa but generally the width of B. obtusa conidia is less than 10um wide, while those of B. stevensii average 12um. B. stevensii has the largest conidia of all four Botryosphaeria species associated with grapevines in Western Australia. Distinct vertical striations are also present on B. rhodina conidia. A key to identify the Botryosphaeria species associated with grapevines in Western Australia has been provided. Vegetative compatibility tests were used to determine the genetic diversity of B. australis and B. obtusa isolates associated with grapevine decline in Western Australia. A total of 20 VCGs were found among the 31 B. australis isolates, which represents a maximum genetic diversity of 38%. Pemberton had the highest genetic diversity of B. australis isolates with 100%. A total of 28 VCGs were obtained among 46 B. obtusa isolates, which represents a genetic diversity of 45%. Pemberton had the highest genetic diversity of B. obtusa isolates with 43%. The maximum genetic diversities of 38 and 45% are intermediate to high when compared to the genetic diversities of other species. There is a lack of information regarding the genetic diversity of Botryosphaeria species. A pathogenicity trial was conducted to determine whether any of the four Botryosphaeria species, B. australis, B. obtusa, B. stevensii and B. rhodina were pathogenic to healthy, rooted grapevine cuttings of two grapevine cultivars grown in Western Australia, Red Globe and Shiraz. There was a significant (p<0.05) between the pathogenicity of the Botryosphaeria isolates. B. australis was the most pathogenic species, followed by B. rhodina and B. stevensii. B. obtusa did not produce lesions on any of the canes and it is possible that B. obtusa has an endophytic part of its lifecycle on grapevines in Western Australia. There was also a significant (p<0.05) difference between the susceptibility of the two cultivars, Red Globe and Shiraz, to the Botryosphaeria species. The Shiraz cuttings were more susceptible to the Botryosphaeria species than the Red Globe cuttings were. This is the first study to associate Botryosphaeria species with grapevine decline in Western Australia. It has highlighted several areas for further research into Botryosphaeria diseases associated with grapevines in Western Australia and the world. These areas include controlling the disease, how the disease is spread among vineyards and the implications of the disease in the long term.

Thesis (PhD (Genetics))--University of Stellenbosch, 2011.
Includes bibliography
ENGLISH ABSTRACT: Grapevine diseases, in particular virus and virus-like diseases, are threatening grapevine industries worldwide; also in South Africa. Grapevine leafroll (GLR) is one of the most important diseases of grapevines, occurring in all grape-producing countries worldwide. Grapevine leafroll-associated virus 3 (GLRaV-3) is known to be closely associated with GLR disease and occurs commonly in South African vineyards. In this study three genetic variants of GLRaV-3 were identified in vineyards of the Western Cape, South Africaby single strand conformation polymorphism (SSCP) profiles generated from a region amplified in ORF5. A specific SSCP profile could be assigned to each variant group and these wereconfirmed by sequencing of the ORF5 regions.These results demonstrated that SSCP analysis on this region in ORF5 provides a fast and reliable indication of the GLRaV-3 variant status of a plant, which in many instances showed mixed infections. The full genome sequence of one representative of each variant group i.e. isolates 621 (group I), 623 (group II) and PL-20 (group III), was determined by sequencing overlapping cloned fragments of these isolates. The sequences of genomic 5’ ends of these isolates were determined by RLM-RACE. Sequence alignment of the 5’UTRs indicated significant sequence and length variation in this region, between the three South African variant groups. Nucleotide sequence alignment of the Hsp70h and CP gene regions of these isolates with those of isolates from elsewhere in the world, followed by phylogenetic analysis, further supported the presence of three GLRaV-3 variants in South Africa, and that two or three additional variant groups occurs elsewhere in the world. We further investigated the prevalence of these three GLRaV-3 variants in mother blocksof different cultivars and from different vine growing regions, using SSCP analysis. The majority of the plants studied, were infected with the group II variant, similar to isolates 623 and GP18. The distribution of the three GLRaV-3 variants within a spatio-temporally recorded cluster of diseased plants was studied by means of SSCP profile analysis. We showed that different GLRaV-3 variants are transmitted to adjacent plants in an infection cluster. Results showed that, in some leafroll disease clusters, the variant that was present in the original GLRaV-3 infected plant of a cluster was transmitted to adjacent plants in a row and across rows. Some plants in the cluster were also infected with variants not present in the original plant. These infections could have been caused by mealybug vectors feeding on plants from surrounding areas and then infecting these plants. The scientific information generated on GLRaV-3 variants in this project contributed to the advancement of our knowledge of genetic variability and provides a basis of further epidemiology and vector-virus studies. The study showed for the first time that different GLRaV-3 variants were transmitted to adjacent plants in a row and across rows in a GLR disease cluster. The diversity detected in the 5’UTR between variants from the three genetic groups provides a platform for the further study of the biological characteristics of GLRaV-3 variants.
AFRIKAANSE OPSOMMING: Wingerdsiektes, veral virus siektes, bedreig wingerd industrieë wêreldwyd, asook die Suid Afrikaanse wingerdbedryf. Rolbladsiekte is een van die belangrikste siektes op wingerd en kom wêreldwyd voor. Die virus, grapevine leafroll-associated virus 3 (GLRaV-3), word sterk geassosieer met Rolbladsiekte en kom wydverspreid voor in Suid Afrikaanse wingerde. Tydens hierdie studie is drie genetiese variante van GLRaV-3 geïdentifiseer in wingerd moederblokke in die Wes-Kaap. Die GLRaV-3 variante is geïdentifiseer met ‘n tegniek wat ‘single-strand conformation polymorphism (SSCP)’ genoem word. Die SSCP profiele was gegenereer vanaf PKR produkte van die ORF5 area op die genoom van GLRaV-3. Die geamplifiseerde produk van die ORF5 gebied is gebruik om die SSCP profiele te verkry en DNA-volgorde data in die gebied het die drie SSCP profiele gestaaf. Hierdie metode om virus variasie te bestudeer in plante is vinnig en betroubare resultate is verkry. Gemengde infeksies, wat gereeld in wingerd voorkom, kon ook met die tegniek opgespoor word. Die volledige nukleotied-volgorde van elkeen van die drie GLRaV-3 genome is volledig bepaal. Die isolate wat die drie variant groepe verteenwoordig is isolaat 621 (groep I), 623 (groep II) en PL-20 (groep III). Die nukleotiedvolgorde in die 5’UTR is bepaal met die RLM-RACE tegniek. Wanneer die 5’UTRs van die drie variante vergelyk is, het dit getoon dat daar verskille is in die volgordes en lengtes voorgekom het. Ander dele van die genoom, o.a. die dopproteïen (CP) en Hsp70 areas, is filogeneties vergelyk met isolate van regoor die wêreld. In die filogenetiese analise is bevind dat die drie GLRaV-3 variante saamgegroepeer het met ander isolate in die wêreld en dat daar elders ook twee to drie addisionele variant groepe van GLRaV-3 voorkom. Die verspreiding van die drie GLRaV-3 variante in wingerde is bestudeer in verskillende kultivars en in verskillende verbouingsgebiede. Die meerderheid van die plante in die studie was geïnfekteer met die groep II variant wat dieselfde is as isolate 623 en GP18. Die voorkoms van die drie variante in ‘n siekte cluster is bestudeer d.m.v SSCP. Die studie het gewys dat verskillende GLRaV-3 variante versprei word na aangrensende plante in ‘n ry en tussen rye. In sommige gevalle is die variant wat in die oorspronklik geïnfekteerde plant voorkom, oorgedra na naasliggende plante. Sommige van die plante in the infeksie area was ook met ander GLRaV-3 variante geïnfekteer wat moontlik deur wolluise oorgedra is vanaf naburige geïnfekteerde plante. Die wetenskaplike inligting wat tydens hierdie studie beskryf word aangaande die identifikasie van GLRaV-3 variante, dra by tot die molekulêre kennis van GLRaV-3 en verskaf ‘n basis vir verdure epidemiologiese -en insek oordragingstudies. Die studie het vir die eerste keer bewys dat verskillende GLRaV-3 variante na aanliggende plante in ‘n ry asook oor rye oorgedra word. Die diversiteit tussen die GLRaV-3 variant groepe in die 5’UTR moet verder ondersoek word en die deel van die genoom kan ‘n belangrike rol speel in die biologiese eienskappe van die variante.

L'evolució cap a una agricultura més compromesa amb el medi ambient ha possibilitat, en viña, el trànsit cap a tècniques de manteniment del sòl més sostenibles, com són les cobertes vegetals. En aquest context es planteja el treball que constitueix la present tesi doctoral, els objectius de la qual són: a) estudiar la validesa de diferents tipus de maneig d'una coberta vegetal així com de les diferents espècies sembrades com a coberta, sobre la comunitat de males herbes presents en una vinya, especialment enfront Cynodon dactylon (L.) Pers.; b) estudiar el comportament germinatiu de Conyza bonariensis (L.) Cronquist; i c) estudiar el potencial fitotòxic de dotze espècies que es poden utilitzar com a coberta i/o encoixinat vegetal enfront de C. bonariensis, Aster squamatus (Spreng.) Hieron i Bassia scoparia (L.) A. J. Els resultats, en conjunt, verifiquen la capacitat de les cobertes vegetals per a controlar males herbes problemàtiques, contribuint a la implementació de manejos integrats més complets.
La evolución hacia una agricultura más comprometida con el medio ambiente ha posibilitado, en viñedos, el tránsito hacia técnicas de mantenimiento del suelo más sostenibles, como son las cubiertas vegetales. En este contexto, se plantea el trabajo que constituye la presente tesis doctoral, cuyos objetivos son: a) estudiar la influencia de distintos manejos de una cubierta vegetal así como de las distintas especies sembradas como cubierta, sobre la comunidad de malas hierbas presentes en un viñedo, especialmente frente a Cynodon dactylon (L.) Pers.; b) estudiar el comportamiento germinativo de Conyza bonariensis (L.) Cronquist; y c) estudiar el potencial fitotóxico de doce especies que se pueden utilizar como cubierta y/o acolchado vegetal frente a C. bonariensis, Aster squamatus (Spreng.) Hieron y Bassia scoparia (L.) A. J. Los resultados, en conjunto, verifican la capacidad de las cubiertas vegetales para controlar malas hierbas problemáticas, contribuyendo a la implementación de manejos integrados más completos.
The evolution of agriculture committed with the environment has enabled a transition, in vineyards, towards more sustainable techniques for soil maintenance, such as ground vegetation covers. In this context, the objectives of the work that constitutes the present doctoral thesis are: a) to study the validity of different ground vegetation covers and the species used for these, for the control of the weed community present in a vineyard, and especially against Cynodon dactylon (L.) Pers.; b) to study the germination behaviour of Conyza bonariensis (L.) Cronquist; and c) to study the phytotoxic potential of twelve species that can be implemented as cover crops and/or mulching against C. bonariensis, Aster squamatus (Spreng.) Hieron, and Bassia scoparia (L.) A. J. The results, taken together, verify the capacity of the ground vegetation covers in controlling problematic weeds, contributing to the implementation of more complete integrated management systems.

Mestrado Vinifera Euromaster - Instituto Superior de Agronomia - UL / Universitá degli Studi di Torino
Vines can encounter death due to several biotic and abiotic diseases and vine plantlets placed to replace them are often not able to compete with adjacent older plants (hypogeal and epigeous competitions). Replanting is a very expensive technique (cost of the vine, fertilizers, planting itself, …) and when vines are replanted in a vineyard they take longer than planting at the implant to get full productivity. Thus the usage of compound such as biostimulants that can accelerate the entrance in full production should be advisable. In this study several compounds have been tested and compared in term of vegetative growth. The effects of FNT 63 (abbr. FNT) stimulating Arbuscolar mycorrhizae, CO-ACTYL NP (abbr. COA), ILSARODDER + ILSACTIGREEN STAR (abbr. ILSA) and BIOHUMIN (abbr. BIO) are shown. The results for these biostimulants were generally not significant compared to untreated vines. Some results were obtained with FNT
N/A

Organic mulches and cover crops mulched in situ were assessed for their effects on B. cinerea primary inoculum and disease levels in inflorescences at flowering and/or bunches at harvest. Organic mulches were used to enhance biological degradation of vine debris to reduce levels of B. cinerea primary inoculum the following season. Four mulch types (anaerobically and aerobically fermented marc (grape pressings), inter-row grass clippings and shredded office paper) were applied under ten-year-old Riesling vines in a ten-replicate randomized block design in New Zealand over two consecutive years. Plastic mesh bags, each containing naturally infected vine debris, were placed under vines on bare ground (control) and at the soil-mulch interface, in winter (July) 2003 and 2004. In each year, half the bags were recovered at flowering (December) and the remainder at leaf plucking (February), for assessment of B. cinerea sporulation from the vine debris and debris degradation rate. Bait lamina probes, which measure soil biological activity, were placed in the soil-mulch interface three weeks before each of the two bag-recovery dates in both years and were then removed and assessed at the same times as were the bags. All mulches led to a reduction in B. cinerea sporulation. This reduction was significantly correlated with elevated rates of vine debris decomposition and increased soil biological activity. Over both years, compared with the controls, all treatments gave a 3-20-fold reduction in B. cinerea sporulation, a 1.6-2.6-fold increase in vine debris degradation and in the two marc and the paper treatments, a 1.8-4-fold increase in activity of soil organisms. The mulches also altered vine characteristics and elevated their resistance to B. cinerea through changes to the soil environment. Functional soil biological activity, as measured by Biolog Ecoplates and bait lamina probes, was increased 2-4 times in the two marc and paper treatments, compared with the control, an effect relating to the elevated soil moisture and reduced temperature fluctuations under these mulches. Soil nutrient levels and the C:N ratios were also affected in these treatments. The mulched paper lowered vine canopy density by up to 1.4 times that of the other treatments, an effect which probably led to elevated light penetration into the canopy and consequent increased canopy temperature, photosynthesis and lowered canopy humidity. These changes to soil and vine characteristics increased grape skin strength by up to 10% in the paper treatment and sugar concentrations by 1.2-1.4 °Brix in the two marc and paper treatments. The severity of B. cinerea infections in the anaerobic marc, aerobic marc and paper treatments were reduced to 12%, 3% and 2.2% of the control, respectively, in field assessments averaged over two consecutive harvests. Cover crops mulched in situ had similar effects to those of the organic mulches, increasing soil biological activity and reducing B. cinerea primary inoculum and the severity of B. cinerea infection in grapes at harvest (2006). Inter-row phacelia and ryegrass were mulched in winter 2005 and compared with a bare ground control, under 10-year-old Chardonnay vines in a ten-replicate randomized block design. Functional soil biological activity increased by 1.5-4.5 times in the two cover crop treatments compared with the control, an effect possibly related to elevated soil moisture in these treatments. This increase in soil moisture and soil biological activity increased vine debris degradation, reduced B. cinerea primary inoculum on the debris and decreased B. cinerea severity at flowering (December 2005) and harvest (April 2006). These results show the potential of organic mulches and cover crops mulched in situ to enhance soil ecosystem services and improve the sustainability of viticultural practices.

Thesis (MSc)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: South Africa is ranked eighth in the world as far as international wine production is concerned and in terms of area under bearing vines South Africa is ranked 12th. In 2011 the wine industry contributed R4 204.4 million to the South African economy in state revenue from wine products. The importance of viticulture to the economy of South Africa forces the industry to limit the effect of all disease causing pathogens in order to keep their competitive edge. Aster yellows (AY) phytoplasma 16SrI-B subgroup was reported for the first time in grapevine (Vitis vinifera L. (Vitaceae)) in South Africa in 2006. Worldwide phytoplasma diseases of grapevine cause serious damage ranging from lower yields to the death of vines. The lack of knowledge about the epidemiology of AY disease makes it difficult to determine the impact of the disease on the South African wine industry. The aim of this study was to conduct surveys in disease-affected vineyards in the Vredendal region to determine the incidence and spatial distribution of the disease in a variety of cultivars. The field surveys based on visual symptoms of AY disease were confirmed by polymerase chain reaction (PCR). A survey was also conducted in and around AY-infected vineyards in search of possible alternative host plants of the phytoplasma. Spatial distribution of AY-affected vines were analysed using the PATCHY spatial analysis package. A rapid decline of AY-affected Chardonnay eventually leading to the death of vines was observed, confirming the sensitivity of Chardonnay towards grapevine yellows infections. Symptomless AY infections occurred and AY could not be detected in all symptomatic vines, which indicate uneven distribution of AY in individual vines. Molecular analyses using PCR-RFLP showed that all vines sampled in the Vredendal vicinity contained AY phytoplasma only. No phytoplasmas were present in any weeds or other possible host plants tested. Although the mean yearly disease incidences of Chardonnay (29.95%) and Chenin blanc (16.64%) were higher than Pinotage (5.80%) over the four-year survey period, there was no statistically significant difference between the disease incidences of these three cultivars. The mean yearly disease incidence showed a trend over time and the disease incidence of the first year was significantly lower than that of the other years. Chardonnay showed a cumulative disease incidence of 37.77% at the end of the 4-year study which means that Chardonnay vineyards can be 100% AY infected in ten years’ time. Spatial distribution patterns of AY-infected vines were mostly non-random with clustering of disease affected vines along and across vine rows. With the exception of one vineyard, aggregation of AY-affected vines mostly occurred on the edge of vineyards adjacent to infected vineyards. This epidemiological study gives an indication of the sensitivity of the different cultivars towards AY, the tempo of spreading and the future impact of the disease on the South African wine industry. It also contributes valuable information towards the development of a management strategy for grapevine yellows disease in South African vineyards.
AFRIKAANSE OPSOMMING: Suid- Afrika is op agtste op die wêreld ranglys wat internasionale produksie van wyn aan betref, en in terme van oppervlakte onder wingerd, is Suid-Afrika 12de. In 2011 het die wynbedryf R4 204.4 miljoen tot die Suid-Afrikaanse ekonomie bygedra in staats inkomste uit wyn produkte. Die belangrikheid van wingerd tot die ekonomie van Suid-Afrika dwing die bedryf om die effek van alle siekteveroorsakende patogene te beperk, om sodoende hul kompeterende voordeel te behou. Aster vergeling (AY) fitoplasma 16SrI-B subgroep is vir die eerste keer in 2006 in wingerd (Vitis vinifera L. (Vitaceae)) in Suid-Afrika waargeneem. Fitoplasma siektes van wingerd veroorsaak wêreldwyd ernstige skade wat wissel van laer opbrengste tot die afsterf van wingerdstokke. Die gebrek aan kennis oor die epidemiologie van astervergeling siekte maak dit moeilik om die impak van die siekte op die Suid-Afrikaanse wynbedryf te bepaal. Die doel van hierdie studie was om ‘n opname te maak in siekte geaffekteerde wingerde in die Vredendal omgewing om sodoende siekte voorkoms en verspreidingspatrone van die siekte in 'n verskeidenheid van kultivars te bepaal. Die veld opnames, gebaseer op visuele simptome van aster vergeling siekte, was bevestig deur polimerase kettingreaksie (PKR). ‘n Opname is ook in en om aster vergeling geaffekteerde wingerde uitgevoer, op soek na moontlike alternatiewe gasheer plante van die fitoplasma. Verspreidingspatrone van astervergeling geaffekteerde wingerde is ontleed met behulp van die PATCHY ruimtelike analise pakket. 'n Vinnige agteruitgang van AY geaffekteerde Chardonnay, wat uiteindelik gelei het tot die afsterf van wingerde, is waargeneem, wat die sensitiwiteit van Chardonnay teenoor wingerdvergeling infeksie bevestig. Simptoomlose astervergeling fitoplasma infeksies kom voor en astervergeling fitoplasma kon nie opgespoor word in alle simptomatiese wingerdstokke nie, wat op oneweredige verspreiding van AY fitoplasma in individuele wingerdstokke dui. Molekulêre ontledings met behulp van PKR-RFLP het getoon dat alle wingerdstokke, wat in die Vredendal omgewing getoets is, slegs astervergeling fitoplasma bevat. Geen fitoplasmas was teenwoordig in enige onkruide of ander moontlike gasheer plante. Hoewel die gemiddelde jaarlikse siekte voorkoms van Chardonnay (29,95%) en Chenin Blanc (16,64%) oor die vier-jaar opname periode hoër was as dié van Pinotage (5,80%), was daar geen statisties beduidende verskil tussen die siekte voorkoms van hierdie drie kultivars nie. Die gemiddelde jaarlikse siekte voorkoms het 'n tendens oor tyd getoon, en die siekte voorkoms van die eerste jaar was betekenisvol laer as dié van die ander jare. Chardonnay het ‘n kumulatiewe siekte voorkoms van 37.77% aan die einde van die 4-jaar studie getoon, wat beteken dat Chardonnay wingerde binne 10 jaar 100% besmet kan wees met AY. Verspreidingspatrone van AY geaffekteerde wingerdstokke was meestal nie-ewekansig met bondeling van geaffekteerde wingerdstokke in en oor wingerd rye. Bondeling van AY geaffekteerde wingerdstokke het, met die uitsondering van een wingerd, meestal op die kant van wingerde aanliggend aan besmette wingerde, voorgekom. Die epidemiologiese studie gee 'n aanduiding van die sensitiwiteit van die verskillende kultivars ten opsigte van AY, die tempo van die verspreiding en die toekomstige impak van die siekte op die Suid-Afrikaanse wynbedryf. Dit dra ook waardevolle inligting by tot die ontwikkeling van 'n strategie vir die bestuur van wingerdvergeling siekte in Suid-Afrikaanse wingerde.

Nowadays we live in densely populated regions and this leads to many environmental issues. Among all pollutants that human activities originate, metals are relevant because they can be potentially toxic for most of living beings. We studied the fate of Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn in a vineyard environment analysing samples of plant, wine and soil. Sites were chosen considering the type of wine produced, the type of cultivation (both organic and conventional agriculture) and the geographic location. We took vineyards that cultivate the same grape variety, the Trebbiano). We investigated 5 vineyards located in the Ravenna district (Italy): two on the Lamone Valley slopes, one in the area of river-bank deposits near Ravenna city, then a farm near Lugo and one near Bagnacavallo in interfluve regions. We carried out a very detailed characterization of soils in the sites, including the analysis of: pH, electric conductivity, texture, total carbonate and extimated content of dolomite, active carbonate, iron from ammonium oxalate, Iron Deficiency Chlorosis Index (IDCI), total nitrogen and organic carbon, available phosphorous, available potassium and Cation Exchange Capacity (CEC). Then we made the analysis of the bulk chemical composition and a DTPA extraction to determine the available fraction of elements in soils. All the sites have proper ground to cultivate, with already a good amount of nutrients, such as not needing strong fertilisations, but a vineyard on hills suffers from iron deficiency chlorosis due to the high level of active carbonate. We found some soils with much silica and little calcium oxide that confirm the marly sandstone substratum, while other soils have more calcium oxide and more aluminium oxide that confirm the argillaceous marlstone substratum. We found some critical situations, such as high concentrations of Chromium, especially in the farm near Lugo, and we noticed differences between organic vineyards and conventional ones: the conventional ones have a higher enrichment in soils of some metals (Copper and Zinc). Each metal accumulates differently in every single part of grapevines. We found differences between hill plants and lowland ones: behaviors of plants in metal accumulations seems to have patterns. Metals are more abundant in barks, then in leaves or sometimes in roots. Plants seem trying to remove excesses of metal storing them in bark. Two wines have excess of acetic acid and one conventional farm produces wine with content of Zinc over the Italian law limit. We already found evidence of high values relating them with uncontaminated environments, but more investigations are suggested to link those values to their anthropogenic supplies.

My research addressed pheromone lure design and the activity of the grape berry moth, Paralobesia viteana, flight and infestation across three years of study. In my lure evaluations, I found all commercial lures contained impurities and inconsistencies that have implications for management. First, sex pheromone concentration in lures affected both target and non-target attraction to traps, while the blend of sex pheromones impacted attraction to P. viteana. Second, over the duration of study, 54 vineyard blocks were sampled for the pest in and around cultivated wine grape in Virginia. The trapping studies indicated earliest and sustained emergence of the spring generation in sex pheromone traps placed in a wooded periphery. Later, moths were detected most often in the vineyard, which indicated that P. viteana emerged and aggregated in woods prior to flying and egg-laying in vineyards. My research supports use of woods and vineyard trap monitoring at both the height of 2 meters and in the periphery of respective environments. These conditions should improve grower efficiency when using trapping as a tool. Cluster infestation was assessed relative to vineyard growth stage and location in the vineyard. My results are in agreement with historical studies that suggest infestation is highest in the periphery of vineyards. However, I found that infestation peaked at veraison before falling somewhat around pre-harvest. This indicated that growers should manage this pest prior to veraison, perhaps as early as budbreak, to prevent the insect from reaching damaging levels when the crop is more susceptible to loss. Lastly, by combining field-based data collection with remote climate and landscape monitoring, growers can achieve a greater level of surveillance of P. viteana. A mash up of remote and vineyard-based data can provide substantive pertinent information for management at both local and regional scales. If one grower identifies moth emergence, then growers nearby potentially can use that same information to initiate models to monitor development of the moth population in their own vineyard. This research complements the notion that the more a community shares information, the broader its applicability becomes to neighbors.
Ph. D.

The study of vegetation‒atmosphere exchanges is today of great interest in order to understand and model plant responses to environmental conditions and their potential influence on global climate change. A special attention is usually given to carbon dioxide (CO2) fluxes and, in general, natural ecosystems such as forests received more attention. In the present work we investigated vegetation‒atmosphere interactions over vineyards, focusing on the annual carbon budget and turbulent transport processes driving exchanges of mass and energy. Vineyard is a complex ecosystem with distributed sources/sinks of scalars (water vapour, carbon dioxide, heat), where vines and soil surface combine to give the overall flux of the canopy. In Northern Italy vineyard inter-row is often grassed, playing then an important role in the whole carbon budget. In this context, the partitioning of net ecosystem CO2 exchange (NEE) into soil and vine components deserves a special attention. We monitored vineyard NEE applying the eddy covariance (EC) method for three years, while soil CO2 flux measurements have been carried on using soil chambers (transparent and dark). In 2015, the annual carbon budget of the vineyard was about ‒ 80 g C m‒2 y‒1, however the largest part of carbon assimilation was due to grassed soil compartment (‒ 60 g C m‒2 y‒1). The interannual variability of seasonal carbon budget showed to be high and significantly affected by heat waves and drought spells in summer. During the growing season of 2014, characterized by plenty of rainfall, NEE reached its maximum value of about ‒ 250 g C m‒2. The organization in rows of the vineyard determines a peculiar turbulent transport dynamics within the canopy. However, the morphological structure of the vineyard is greatly variable over the year, shifting from an empty canopy during vine dormancy to dense foliage in summer. We investigated the influence of foliage development on turbulence statistics deploying a vertical array of sonic anemometers. Turbulent flow showed to be greatly influenced by canopy structure. Without leaves, turbulent regime is typical of a rough‒wall boundary layer flow, whereas at full foliage development it assumes the features of a mixing‒layer flow, even if the inflection point at canopy top is weak, due to sparseness of the vineyard. Coherent structures involved in momentum transport and their temporal scales have been also investigated, showing the increasing importance of sweeps throughout the growing season. The average duration of dominating coherent structures was in the order of 6 ‒ 10 s and no clear influence by canopy structure evolution was detected. The research demonstrated the importance of long‒term monitoring of vegetation‒atmosphere exchanges, and also the complexity of turbulent transport dynamics in the canopy space. However, only a thorough comprehension of this mechanics could lead to a solid interpretation of the role of vegetation in fundamental biogeochemical cycles.
Lo studio delle interazioni tra vegetazione e atmosfera è oggi un tema di grande interesse nell’ottica di migliorare la comprensione della risposta delle piante alle variabili ambientali e la modellizzazione del loro ruolo nel cambiamento climatico globale. Particolare attenzione è di solito rivolta ai flussi di anidride carbonica (CO2) e, in genere, gli ecosistemi naturali come le foreste hanno ricevuto una maggiore attenzione. In questa ricerca sono state studiate le interazioni vegetatione-atmosfera su una coltura agraria importante per il bacino mediterraneo, quale il vigneto, focalizzandosi sul monitoraggio del bilancio annuale di carbonio e approfondendo lo studio della meccanica del trasporto turbulento che è alla base degli scambi di energia e materia. Il vigneto è un sistema complesso con diverse sorgenti e sink di scalari (vapore d’acqua, anidride carbonica, calore), in cui le due principali componenti, vite e suolo, compongono il flusso totale della canopy in un rapporto che varia nel corso dell’anno. Nei vigneti del Nord Italia, l’interfila è solitamente non lavorata e inerbita, giocando un ruolo importante nel bilancio del carbonio del sistema. In questo contesto, risulta cruciale la ripartizione dello scambio netto di CO2 dell’ecosistema (Net Ecosystem Exchange, NEE) nelle componenti suolo e vite. Nel corso di questa indagine, la NEE di un vigneto è stata monitorata per tre anni utilizzando la tecnica micrometeorologica dell’ eddy covariance (EC), mentre la misura dei flussi di CO2 al suolo è stata effettuata con camere (a cupola trasparente e oscura). Nel 2015, il bilancio annuale di carbonio del vigneto è stato di circa ‒ 80 g C m‒ 2 a‒ 1, dimostrando quindi la capacità di agire da sink, ma la maggior parte dell’assimilazione è risultata legata al suolo inerbito (‒ 60 g C m‒2 a‒1). In ogni caso, il sistema ha dimostrato un’elevata variabilità interannuale del bilancio del carbonio stagionale, in cui ondate di calore e periodi di siccità estivi hanno giocato un ruolo primario. Nella stagione 2014, caratterizzata da un regime di precipitazione abbondante, la NEE ha raggiunto il valore massimo di circa ‒ 250 g C m‒2. L’organizzazione del vigneto in filari determina una particolare dinamica del trasporto turbolento dentro canopy. Inoltre, la struttura morfologica del vigneto è altamente variabile durante il corso dell’anno, passando da una canopy praticamente vuota nel periodo di dormienza della vite a una situazione dove il fogliame è denso e concentrato nelle file al culmine della stagione vegetativa. L’influenza dello sviluppo della densità fogliare sulle statistiche della turbolenza è stato studiato installando un profilo verticale di anemometri ad ultrasuoni. Il flusso turbolento è risultato fortemente influenzato dalla struttura della canopy. Senza foglie, il regime turbolento è caratteristico di un flusso di parete, mentre con lo sviluppo completo del fogliame assume le proprietà tipiche di un flusso con mixing‒layer, sebbene il flesso al limite superiore della canopy sia poco accentuato, a causa della bassa densità fogliare del vigneto. Infine, è stata condotta un’analisi specifica delle strutture coerenti coinvolte nel trasporto di quantità di moto e sulle loro scale temporali. L’importanza di eventi discendenti che trasportano aria più veloce del flusso medio (sweeps) è aumentata nel corso della stagione. La durata media delle strutture coerenti dominanti è stato nell’ordine di 6 ‒ 10 s e, in questo caso, non è stata riscontrata nessuna chiara correlazione con lo sviluppo della struttura della canopy. Lo studio ha messo in evidenza l’importanza del monitoraggio a lungo termine degli scambi tra vegetazione e atmosfera, ma anche la complessità dei fenomeni di trasporto turbolento che li caratterizzano. Tuttavia, solo la piena comprensione della meccanica di questi processi può portare alla corretta interpretazione del ruolo della vegetazione nei cicli biogeochimici più fondamentali.

Dissertation (PhD)--University of Stellenbosch, 2004.
ENGLISH ABSTRACT: Wine is the product of a complex biological and biochemical interaction between grapes and different microorganisms (fungi, yeasts, lactic acid bacteria and acetic acid bacteria, as well as the mycoviruses and bacteriophages affecting them) in which yeasts play the most important role regarding the alcoholic (primary) fermentation. These wine-associated yeasts can be divided into Saccharomyces and non-Saccharomyces yeasts. During fermentation, there is a sequence of dominance by the various non-Saccharomyces yeasts, followed by Saccharomyces cerevisiae, which then completes the fermentation. This is especially evident in spontaneously fermenting must, which has a low initial S. cerevisiae concentration. Some non- Saccharomyces yeasts can also be found throughout the fermentation. The non- Saccharomyces presence in the fermentation can affect wine quality, either positively or negatively. A positive contribution could be especially useful to improve wines produced from grape varieties with a neutral flavour profile due to non-optimal climatic conditions and/or soil types. As part of a comprehensive South African research programme, the specific objectives of this study were: the isolation of indigenous non-Saccharomyces yeasts from vineyards and musts; the identification of these isolates; the characterisation and evaluation of predominant species under winemaking conditions; and the development of a protocol for their use in enhancing wine quality. Initially, 720 isolates representing 24 different species, were isolated from grape (vineyard) and must samples taken over three vintages from four distinctly different wine producing regions. The isolates were characterised and grouped utilising biochemical profiles and DNA karyotyping, whereupon representative isolates were identified. The yeast species that had the highest incidence of predominance in the vineyard was Kloeckera apiculafa. However, some vineyard samples were characterised by low numbers or absence of this yeast, which is not according to generally accepted norms. Other species that also predominated in a few of the vineyard samples were Candida pulcherrima, Kluyveromyces thermofolerans, Rhodotorula sp. and Zygosaccharomyces bailii. Generally, there was a greater diversity of yeasts in the processed must than from the vineyard samples. Furthermore, while each sample showed a different yeast population, no pattern linking species to climatic zone was observed. Four species i.e. Candida collieulosa, Candida pulcherrima, Candida stel/ata and Kloeckera apiculata, were found to predominate in grape must samples. Representative strains consequently received further attention during laboratory and small-scale winemaking trials. A protocol was developed whereby individual species could be used in co-inoculated fermentations with S. cerevisiae in the small-scale production of wine. An improvement in wine quality was achieved and it was found that there was a link between specific species and grape cultivar. The ability of C. pulcherrima to improve Chenin blanc wine quality was investigated further. Results over three vintages showed that the wine produced by the co-inoculated fermentation was superior to that of a reference wine (produced by S. cerevisiae only). The improvement in wine quality was not linked to increased ester content nor were the standard chemical analyses adversely affected. The effects of pH and wine production parameters i.e. 802, fermentation temperature and use of di-ammonium phosphate (DAP), on this yeast followed the same pattern as that known for S. cerevisiae. This study was successfully completed and the developed protocol can be used for the improvement of Chenin blanc wine where additional aroma and quality is needed.
AFRIKAANSE OPSOMMING: Wyn is die produk van 'n komplekse biologiese en biochemiese interaksie tussen druiwe en mikroorganismes (swamme, giste, melksuurbakterieë, asynsuurbakterieë, asook die mikovirusse en bakteriofage wat hul beïnvloed) waar gis die belangrikste rol speel ten opsigte van die alkoholiese (primêre) fermentasie. Die betrokke giste kan in Saccharomyces- en nie-Saccharomyces-giste verdeel word. Tydens gisting vind daar 'n opeenvolging van dominansie deur die verskillende nie-Saccharomyces giste plaas, gevolg deur Saccharomyces cerevisiae, wat dan die gisting voltooi. Dit is veral in spontaan fermenterende mos, waarin aanvanklik lae konsentrasies S. cerevisiae-gisselle voorkom, waarneembaar. Sekere nie-Saccharomyces-giste kan ook regdeur die verloop van fermentasie gevind word. Die teenwoordigheid van nie-Saccharomyces-giste kan 'n bydrae maak tot wynkwaliteit, hetsy positief of negatief. 'n Positiewe bydrae kan veral nuttig wees vir die verbetering van wyn geproduseer van druifsoorte met neutrale geurprofiele as gevolg van nie-optimale klimaatstoestande en/of grondtipes. As deel van 'n uitgebreide Suid-Afrikaanse navorsingsprogram, was die doelwitte van hierdie studie soos volg: die isolasie van inheemse nie-Saccharomyces-giste vanuit wingerde en mos; die identifikasie van hierdie isolate; die karakterisering en evaluering van spesies wat tydens wynbereiding oorheers; en die ontwikkeling van 'n protokol waarin geselekteerde nie- Saccharomyces-giste gebruik kan word vir die verbetering van wynkwaliteit. Druif- en mosmonsters is oor drie oestye vanuit vier duidelik onderskeibare wynproduserende gebiede geneem en 720 isolate, verteenwoordigend van 24 verskillende spesies, is hieruit geïsoleer. Hierdie isolate is volgens biochemiese profiele en DNA-kariotipering gekarakteriseer en gegroepeer waarna verteenwoordigende isolate geïdentifiseer is. Die gisspesie wat die meeste in wingerde voorgekom het, was Kloeckera apiculata. Sommige wingerde is egter deur lae getalle of afwesigheid van dié gis gekenmerk, In feit wat afwyk van die algemeen aanvaarde norm. Ander spesies, nl. Candida pulcherrima, Kluyveromyces thermotolerans, Rhodotorula sp. en Zygosaccharomyces bailii, het ook in enkele gevalle in die wingerdmonsters oorheers. Oor die algemeen was daar 'n groter diversiteit van giste in die geprosesseerde mos as in die wingerdmonsters. Verder is elke monster gekenmerk deur verskillende gispopulasies, maar geen verband tussen gisspesie en klimaatsone is waargeneem nie. Vier spesies, nl. Candida collieulosa, Candida pulcherrima, Candida stel/ata en Kloeckera apiculata, het in hoë getalle in die druiwemosmonsters oorheers en verteenwoordigende rasse het verdere aandag tydens laboratorium- en kleinskaalse wynmaakproewe geniet. 'n Protokol, waar hierdie rasse individueel gebruik is in gesamentlike geïnokuleerde fermentasies met S. cerevisiae vir die kleinskaalse produksie van wyn, is ontwikkel. 'n Verbetering in wynkwaliteit is verkry en daar is 'n verband tussen spesifieke gisspesies en druifvariëteit gevind. Gevolglik is die vermoë van C. pulcherrima om die gehalte van Chenin blanc wyn te verbeter, verder ondersoek. Resultate oor drie oesjare het gewys dat die wyn wat met die C. pulcherrima / S. cerevisiae kombinasie geproduseer is, beter was as 'n verwysingswyn (deur slegs S. cerevisiae geproduseer). Die waargenome verbetering in wynkwaliteit was egter nie aan 'n verhoging in esterinhoud te danke nie en die standaard chemiese analises het geen negatiewe afwyking uitgewys nie. Verder is gevind dat die effek van pH en wynproduksieparameters, nl. die gebruik van S02, fermentasietemperatuur en die gebruik van di-ammoniumfosfaat (DAP), dieselfde patroon as die bekend vir S. cerevisiae gevolg het. Die ontwikkelde protokol kan nou aangewend word waar verhoogde Chen in blanc wynaroma en kwaliteit verlang word.

Il marciume del grappolo, causato da Botrytis cinerea, è una delle principali malattie che colpiscono la vite. Botrytis cinerea si sviluppa e cresce attivamente come patogeno necrotrofo e saprofita su diversi substrati. In vigneto, B. cinerea può produrre un ampio numero di conidi in un’ampia gamma di condizioni ambientali. Botrytis cinerea ha diversi pathway d’infezione e le infezioni occorrono principalmente in due periodi: dalla fioritura allo sviluppo dei giovani grappoli, e dopo invaiatura alla raccolta. A causa della complessità del ciclo di vita di B. cinerea e all’esistenza di questi diversi pathway d’infezione, i fungicidi vengono normalmente applicati a fine della fioritura (A), pre-chiusura del grappolo (B), invaiatura (C), e prima della raccolta (D). Le applicazioni durante la prima parte della stagione (A e B) hanno come obiettivo: i) la riduzione della germinazione dei conidi e le infezioni fiorali, ii) la prevenzione delle infezioni latenti delle bacche, e iii) la disinfezione dei residui di fioritura. Le applicazioni successive all’invaiatura (C e D) hanno lo scopo non solo di prevenire le infezioni durante la maturazione ma anche di disinfestare i residui di fioritura rimasti all’interno del grappolo. Questa strategia, basata su quattro trattamenti, garantisce una buona protezione contro il marciume del grappolo in vigneto, tuttavia presenta alcuni limiti: i) si tratta di un approccio preventivo che non considera il reale rischio d’infezione, con il conseguente effetto di eseguire trattamenti non necessari; ii) aumenta la probabilità che si sviluppino popolazioni resistenti ai fungicidi; iii) implica potenziali risvolti negativi sulla salute umana e sull’ambiente. Negli ultimi anni, nuove tipologie di prodotti, come gli agenti di biocontrollo (BCAs) e i botanicals, sono state proposte per ridurre l’uso eccessivo di prodotti chimici e aumentare la sostenibilità del controllo del marciume del grappolo in vigneto. Lo scopo di questa tesi di Dottorato è stato: i) comparare diverse strategie di controllo e valutare l’interazione tra fungicidi con diversi timing di applicazione, ii) valutare l’effetto sulla colonizzazione e sporulazione di B. cinerea su residui fiorali di diversi prodotti (fungicidi, agenti di biocontrollo, e botanicals) applicati con diversi timing; iii) valutare un modello meccanicistico sviluppato da González-Domínguez et al. (2015); e iv) includere all’interno di un modello per il biocontrollo, sviluppato da Jeger et al. (2009), l’effetto delle condizioni ambientali sulle interazioni BCA-patogeno.
Botrytis bunch rot (BBR), caused by Botrytis cinerea, is one of the main diseases affecting grapevine. Botrytis cinerea develops and actively grows as necrotrophic pathogen and as saprophyte on different substrates. In grapevine, B. cinerea can produce a large number of conidia on bunch and leaf trash and rotted berries under a wide range of environmental conditions. Botrytis cinerea has multiple infection pathways and infection mainly occurs in two periods: from flowering to young cluster development, and after veraison to harvest. Due to the complexity of the B. cinerea life cycle and the existence of these different infection pathways, fungicides are usually applied at the end of flowering (A), pre-bunch closure (B), veraison (C), and before harvest (D). The early season applications (A and B) are aimed at: i) reducing conidial germination and infection of flowers, ii) preventing latent infections of berries, and iii) disinfesting the bunch trash. The later-season applications (i.e., the applications from veraison until harvest; C and D) are aimed not only at preventing berry infection during ripening but also at disinfesting bunch trash in order to reduce the inoculum load. This fungicide schedule may results in unnecessary sprays because the applications are preventive and do not take into account the real risk of BBR infections. In the last decades, new products, like biological control agents (BCAs) and botanicals, have been proposed for reducing the excessive use of chemicals in agriculture and increase the sustainable of BBR control in vineyards. The aim of this Doctoral work was to: i) compare different control strategies and evaluate the interactions among fungicides applied at different timings; ii) investigate the effects of different products (fungicides, biological control agents, and botanicals) applied at different timings on B. cinerea bunch trash colonization and sporulation; iii) evaluate a weather-driven mechanistic model developed by González-Domínguez et al. (2015); and iv) include into a model for biological control, developed by Jeger et al. (2009), the effect of environmental conditions on the pathogen-BCA interactions.

Il marciume del grappolo, causato da Botrytis cinerea, è una delle principali malattie che colpiscono la vite. Botrytis cinerea si sviluppa e cresce attivamente come patogeno necrotrofo e saprofita su diversi substrati. In vigneto, B. cinerea può produrre un ampio numero di conidi in un’ampia gamma di condizioni ambientali. Botrytis cinerea ha diversi pathway d’infezione e le infezioni occorrono principalmente in due periodi: dalla fioritura allo sviluppo dei giovani grappoli, e dopo invaiatura alla raccolta. A causa della complessità del ciclo di vita di B. cinerea e all’esistenza di questi diversi pathway d’infezione, i fungicidi vengono normalmente applicati a fine della fioritura (A), pre-chiusura del grappolo (B), invaiatura (C), e prima della raccolta (D). Le applicazioni durante la prima parte della stagione (A e B) hanno come obiettivo: i) la riduzione della germinazione dei conidi e le infezioni fiorali, ii) la prevenzione delle infezioni latenti delle bacche, e iii) la disinfezione dei residui di fioritura. Le applicazioni successive all’invaiatura (C e D) hanno lo scopo non solo di prevenire le infezioni durante la maturazione ma anche di disinfestare i residui di fioritura rimasti all’interno del grappolo. Questa strategia, basata su quattro trattamenti, garantisce una buona protezione contro il marciume del grappolo in vigneto, tuttavia presenta alcuni limiti: i) si tratta di un approccio preventivo che non considera il reale rischio d’infezione, con il conseguente effetto di eseguire trattamenti non necessari; ii) aumenta la probabilità che si sviluppino popolazioni resistenti ai fungicidi; iii) implica potenziali risvolti negativi sulla salute umana e sull’ambiente. Negli ultimi anni, nuove tipologie di prodotti, come gli agenti di biocontrollo (BCAs) e i botanicals, sono state proposte per ridurre l’uso eccessivo di prodotti chimici e aumentare la sostenibilità del controllo del marciume del grappolo in vigneto. Lo scopo di questa tesi di Dottorato è stato: i) comparare diverse strategie di controllo e valutare l’interazione tra fungicidi con diversi timing di applicazione, ii) valutare l’effetto sulla colonizzazione e sporulazione di B. cinerea su residui fiorali di diversi prodotti (fungicidi, agenti di biocontrollo, e botanicals) applicati con diversi timing; iii) valutare un modello meccanicistico sviluppato da González-Domínguez et al. (2015); e iv) includere all’interno di un modello per il biocontrollo, sviluppato da Jeger et al. (2009), l’effetto delle condizioni ambientali sulle interazioni BCA-patogeno.
Botrytis bunch rot (BBR), caused by Botrytis cinerea, is one of the main diseases affecting grapevine. Botrytis cinerea develops and actively grows as necrotrophic pathogen and as saprophyte on different substrates. In grapevine, B. cinerea can produce a large number of conidia on bunch and leaf trash and rotted berries under a wide range of environmental conditions. Botrytis cinerea has multiple infection pathways and infection mainly occurs in two periods: from flowering to young cluster development, and after veraison to harvest. Due to the complexity of the B. cinerea life cycle and the existence of these different infection pathways, fungicides are usually applied at the end of flowering (A), pre-bunch closure (B), veraison (C), and before harvest (D). The early season applications (A and B) are aimed at: i) reducing conidial germination and infection of flowers, ii) preventing latent infections of berries, and iii) disinfesting the bunch trash. The later-season applications (i.e., the applications from veraison until harvest; C and D) are aimed not only at preventing berry infection during ripening but also at disinfesting bunch trash in order to reduce the inoculum load. This fungicide schedule may results in unnecessary sprays because the applications are preventive and do not take into account the real risk of BBR infections. In the last decades, new products, like biological control agents (BCAs) and botanicals, have been proposed for reducing the excessive use of chemicals in agriculture and increase the sustainable of BBR control in vineyards. The aim of this Doctoral work was to: i) compare different control strategies and evaluate the interactions among fungicides applied at different timings; ii) investigate the effects of different products (fungicides, biological control agents, and botanicals) applied at different timings on B. cinerea bunch trash colonization and sporulation; iii) evaluate a weather-driven mechanistic model developed by González-Domínguez et al. (2015); and iv) include into a model for biological control, developed by Jeger et al. (2009), the effect of environmental conditions on the pathogen-BCA interactions.

The project of this doctoral thesis arisen from a previous work of vineyard yeast isolation, collection and characterization, which was held at the Wine Microbiology laboratory of the University of Padova in Conegliano (CIRVE). Some genomic variations have been uncovered thanks to the genome sequencing of four S. cerevisiae strains. The relationship between the yeast genotype and phenotype is one of the most debated topics in wine microbiology. Aimed to trying deepening the knowledge regarding the genomic variations effects on the oenological performances of wine yeasts, this thesis is focused on the diffusion of some genomic variations in vineyard yeasts populations and on their implications on the strains technological phenotype. The oenological characterization of Brazilian Saccharomyces cerevisiae yeast strains has been performed, paying attention to the link between the local agricultural practices and the strains biodiversity in vineyard. Results showed that the heavy use of Cu in plant protection contributed to develop a strong Cu tolerance in the autochthonous population. This effect didn’t affect the strains genotype biodiversity so those vineyards were confirmed as great reservoir for wine yeast strains isolation and selection. The strains Cu and SO2 tolerance has been studied on Italian and Brazilian S. cerevisiae vineyard strains. The studied topics were the relationship between the CUP1 Copy N° Variation and the Cu tolerance and the relationship between the presence of two chromosomal translocations and the SO2 tolerance. Results evidenced an association between genetic traits and tolerant phenotypes at vineyard population level, in particular for Cu tolerance and the CUP1 CNV. Moreover, hints of an association between Cu and SO2 tolerance are discussed. The fermentable carbon sources uptake in 4 S. cerevisiae strains has been investigated. The expression of the hexose transporters genes has been analysed during stationary phase of synthetic must fermentation. The study involved FSY1, found in EC1118 and encoding for a high affinity fructose/H+ symporter, present in the 25% of the vineyard strains. Gene expression analysis evidenced that strain-specificity is not related to a single gene but it depends on the main regulation pathways. The higher utilization of FSY1 by P301.9 and R31.3 seems counterbalancing their higher glucose preference during fermentation. The FSY1 putative role in wine yeast seems to be its acting as helper of more effective carbon sources utilization at the latest fermentation stages. This work can contribute in improving the wine yeasts characterization by giving a tool for their distinction for fitness in the winemaking environment, at transcriptional level. Lastly, S. cerevisiae strains EC1118 and QA23have been studied under the Martinotti’s method for sparkling wine production. The yeast cells viability during the pied-de-cuve preparation, the pressure evolution in autoclave and the cells response to the wine chilling at the end of the second fermentation were taken into account. During the wine chilling, cells have been recovered for the total RNA extraction to be used in transcriptomic analysis. Preliminary results show that EC1118 has been characterized by lower cells viability than QA23 since the ethanol adaptation procedure and all along the fermentative process. This difference reflected to the pressure evolution kinetic. Data of the total RNA extraction, quantification, integrity and quality check are also presented.
Il progetto di questa tesi di dottorato nasce da un precedente lavoro di isolamento, raccolta e caratterizzazione di lieviti da vigneto. Alcune variazioni genomiche sono state scoperte grazie al sequenziamento del genoma di quattro ceppi S. cerevisiae. La relazione tra genotipo e fenotipo nel lievito è uno degli argomenti più dibattuti in enologia. Con l’obiettivo di approfondire la conoscenza riguardo alle possibili conseguenze delle variazioni genomiche sulle prestazioni enologiche dei lieviti, questa tesi si concentra sulla diffusione di alcune variazioni genomiche nelle popolazioni di lieviti di vigneto e sulle loro implicazioni sul fenotipo tecnologico del lievito. È stata caratterizzata una popolazione di ceppi brasiliani della specie Saccharomyces cerevisiae, prestando attenzione al legame tra le pratiche agricole locali e la biodiversità dei ceppi in vigneto. I risultati hanno mostrato che l’importante uso del rame nella protezione della vite ha contribuito a sviluppare una forte tolleranza a questo metallo nella popolazione di lieviti autoctona. Questo effetto non ha influenzato la biodiversità genotipica dei ceppi di lievito nei vigneti interessati, che si sono stati confermati un’importante riserva per l’isolamento e la selezione dei ceppi di lievito enologici. La tolleranza verso il rame e i solfiti è stata studiata tra i ceppi S. cerevisiae delle collezioni di lieviti italiani e brasiliani. Gli argomenti trattati hanno riguardato il rapporto tra il CUP1 CNV (Copy N° Variation), e il rapporto tra la tolleranza al rame e la presenza di due traslocazioni cromosomiche e la tolleranza ai solfiti. I risultati hanno evidenziato un'associazione tra i tratti genetici e i fenotipi tolleranti a livello di popolazione di vigneto, in particolare tra la tolleranza al rame e il CUP1 CNV. È inoltre discussa la possibile associazione tra la tolleranza al rame e quella ai solfiti. È stato studiato l'assorbimento delle fonti di carbonio fermentabili in 4 ceppi S. cerevisiae. L'espressione genica dei trasportatori di esosi è stata analizzata durante la fase stazionaria della fermentazione in mosto sintetico. Lo studio ha coinvolto FSY1, gene trovato in EC1118 codificante per un simporto ad alta affinità fruttosio/H+, presente nel 25% dei ceppi di vigneto. L'analisi dell'espressione genica ha evidenziato che la ceppo-specificità non è correlata a un singolo gene ma dipende dalle vie principali di regolazione. Il maggiore utilizzo di FSY1 da parte di P301.9 e R31.3 sembra controbilanciare la loro elevata preferenza per il glucosio durante la fermentazione. Il ruolo di FSY1 nel lievito enologico sembra essere quello di aiuto per l'utilizzo più efficiente delle fonti di carbonio nelle ultime fasi fermentative. Questo lavoro può contribuire alla caratterizzazione dei lieviti enologici dando uno strumento per la loro distinzione per il fitness nell'ambiente di vinificazione a livello trascrizionale. Infine, i ceppi EC1118 e QA23 sono stati studiati in spumantizzazione secondo il metodo Martinotti, utilizzato nella produzione del Prosecco DOC Spumante (Conegliano-Valdobbiadene). È stato valutato la vitalità delle cellule di lievito durante la preparazione del pied-de-cuve, l'evoluzione di pressione in autoclave e la risposta delle cellule al raffreddamento del vino a fine processo. Durante il raffreddamento forzato le cellule sono state campionate per l'estrazione del RNA totale per la successiva analisi trascrittomica. I risultati preliminari mostrano che EC1118 è stato caratterizzato da una vitalità cellulare sempre inferiore rispetto a QA23, dalla fase di adattamento all'etanolo e per tutto il processo. Questa differenza si riflette sulla cinetica di evoluzione della pressione. Sono inoltre presentati e discussi i dati riguardanti l’estrazione, quantificazione, integrità e verifica della qualità del RNA totale.

Micro-irrigation scheduling, fertigation and mulching can be used by growers to improve the nutrient and water-use efficiency of crop production. Agriculture contributes to global warming through emission of greenhouse gases CO₂ N₂O, and CH₄. There is little information about how management practices affect N₂O emissions from vineyard and orchard soils. In a two year field experiment, N₂O fluxes from a grape (Vitis vinifera L.; Merlot) vineyard and an apple (Malus domestica Borkh; Ambrosia) orchard under microirrigation in the semiarid Okanagan Valley of British Columbia were measured using static chambers. Soil mineral N and organic carbon, environmental variables and fruit yield were also monitored. Treatments in the grape vineyard involved micro-irrigation types (Drip or Micro-sprinkler), nitrogen sources (surface-applied compost or fertigated Urea; 40kg N ha‐¹), and two floor managements (surface-applied shredded bark and wood Mulch or Clean - bare soil). Treatments in the apple orchard involved drip irrigation frequency (twice per day or twice per day on every 2nd day) delivering the same total amount of water, orchard floor management (Mulch or Clean) and nitrogen application rate applied as calcium nitrate by fertigation (20 or 40 g N tree‐¹). Spring thaw accounted for 30 to 50% of annual emissions in both experiments. Over a period of two complete years in the grape vineyard Micro-sprinkler irrigation reduced growing season N₂O emissions by 29% (compared to Drip) and on an annual basis Mulch decreased them by 28% (compared to Clean ). In the apple orchard irrigation every 2nd day reduced N₂O emissions by 30% and application of Mulch reduced them by 20%. Reduced drip irrigation frequency and mulching may provide an opportunity for suppressing N₂O emissions from drip-irrigated vineyards and orchards. There was alsolarge spatial variability of N₂O and CO₂ emissions with respect to distance relative to the apple tree and dripper locations. The emission factor (N emitted as N₂O per unit of total applied N) from the applied fertilizer (uncorrected for background emission) across all treatments averaged 2.8% in the vineyard and 2.4% in the orchard. The 1% default IPCC emission factor likely underestimates N₂O emissions from these systems.
Irving K. Barber School of Arts and Sciences (Okanagan)
Earth and Environmental Sciences, Department of (Okanagan)
Graduate

Thesis (MScAgric (Conservation Ecology and Entomology))--Stellenbosch University, 2008.
ENGLISH ABSTRACT: Ant infestations comprising the Argentine ant Linepithema humile (Mayr), common pugnacious ant Anoplolepis custodiens (F. Smith) and cocktail ant Crematogaster peringueyi Emery are a widespread pest problem in South African vineyards. Integrated Pest Management (IPM) programmes aimed at suppressing the problematic honeydew excreting vine mealybug Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae) on grapes must include ant control to optimize the effectiveness and efficacy of mealybug natural enemies. If ants are eliminated, natural enemies are able to contain mealybugs below the Economic Threshold Level (ETL). Current strategies for ant control are limited and generally include the application of long term residual insecticides that are detrimental to the environment, labour intensive to apply and can disrupt natural biological control if applied incorrectly. A more practical method of ant control using low toxicity baits was therefore investigated. Field bait preference and bait acceptance assessments aimed at determining bait repellency and palatability, respectively, were carried out during spring, summer and autumn in three vineyards of the Cape winelands region during 2007/08. Five toxicants comprising gourmet ant bait (0.5%), boric acid (0.5%), fipronil (0.0001%), fenoxycarb (0.5%) and spinosad (0.01%) dissolved in 25% sugar solution were tested against a 25% sucrose solution control. Gourmet ant bait was significantly more preferred and accepted by all ant species than the other baits. Laboratory bait efficacy assessments using four insecticides (gourmet, boric acid & spinosad) at concentrations of 0.25; 0.5; 1; 2 and 4 times the field dose and fipronil at 0.015625; 0.03125; 0.0625; 0.125; 0.25 times the field dose were carried out. Results revealed that boric acid (2%), gourmet ant bait (2%) and fipronil (1.0 X 10-5%) exhibited delayed toxicity for L. humile and C. peringueyi while spinosad (0.01%) showed delayed action on L. humile. Field foraging activity and food preference tests were also carried out for the three ant species during 2007/08. Foraging activity trials revealed that vineyard foraging activity of L. humile is higher relative to A. custodiens and C. peringueyi. This means fewer bait stations are required for effective L. humile control making low toxicity baits a more affordable and practical method of controlling L. humile than the other two ant species. Food preference trials showed that L. humile and C. peringueyi have a high preference for sugar while A. custodiens significantly preferred tuna over other baits. However, all ant species had a preference for wet baits (25% sugar water, 25% honey, tuna & agar) as opposed to dry ones (fish meal, sorghum grit, peanut butter & dog food). This research concludes that low toxicity baits show potential in ant pest management and can offer producers with a more practical, economical and environmentally friendly method of ant control which is compatible with vineyard IPM programmes.
AFRIKAANSE OPSOMMING: Mierbesmetting wat uit die Argentynse mier Linepithema humile (Mayr), die gewone malmier Anoplolepis custodiens (F. Smith) en die wipstertmier Crematogaster peringueyi Emery bestaan, is ’n plaagprobleem wat wydverspreid in Suid-Afrikaanse wingerde voorkom. Programme vir geïntegreerde plaagbeheer (GPB) wat daarop gemik is om die wingerdwitluis Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae) – wat ’n probleem is weens die heuningdou wat dit afskei – op druiwe te beheer, moet mierbeheer insluit om sodoende die uitwerking en doeltreffendheid van die witluis se natuurlike vyande die beste te benut. As miere uitgeskakel kan word, sal dit vir die natuurlike vyande moontlik wees om die witluis sodanig te beheer dat dit onder die ekonomiese drempelvlakke (EDV) bly. Huidige strategieë om miere te beheer, is beperk en sluit gewoonlik die toediening van insekdoders in wat lank neem om in die grond af te breek, wat skadelik vir die omgewing is, waarvan die toediening arbeidsintensief is en wat die natuurlike biologiese beheer kan versteur indien dit verkeerd toegepas word. Daarom is ’n meer praktiese metode ondersoek waar miere deur die gebruik van lae toksisiteit lokase beheer word. Ondersoeke na lokaasvoorkeure en lokaasaanvaarbaarheid in die praktyk, wat daarop gemik is om te bepaal of die lokaas onderskeidelik afstootlik en smaaklik bevind word, is oor lente, somer en herfs in drie verskillende wingerde in die Kaapse wynlandstreek gedurende die 2007/08-seisoen uitgevoer. Vyf gifstowwe, bestaande uit gourmet ant bait (0.5%), boorsuur (0.5%), fiproniel (0.0001%), fenoksiekarb (0.5%) en spinosad (0.01%) wat in ’n 25%-suikeroplossing opgelos is, is getoets teenoor ’n kontrole wat uit ’n 25%-sukrose-oplossing bestaan. Al die mierspesies het gourmet ant bait bo die ander lokase verkies en aanvaar. In die laboratorium is ondersoeke gedoen om die doeltreffendheid van die lokase te bepaal deur vier insekdoders (gourmet ant bait, boorsuur en spinosad) te gebruik in konsentrasies van 0.25; 0.5; 1; 2 en 4 keer die dosis in die praktyk en fiproniel teen 0.015625; 0.03125; 0.0625; 0.125; 0.25 keer die dosis in die praktyk. Resultate het getoon dat boorsuur (2%), gourmet ant bait (2%) en fiproniel (1.0 X 10-5%) vertraagde toksisiteit getoon het vir L. humile en C. peringueyi, terwyl spinosad (0.01%) ’n vertraagde uitwerking getoon het op L. humile. Toetse om kossoekaktiwiteite in die praktyk en die voedselvoorkeure van die drie mierspesies te ondersoek, is ook gedurende die 2007/08-seisoen gedoen. Proewe oor kossoekaktiwiteite het getoon dat hierdie aktiwiteite in die wingerd by L. humile hoër is in verhouding met A. custodiens en C. peringueyi. Dit beteken dat minder lokaasstasies nodig is om L. humile doeltreffend te beheer en lei daartoe dat lae toksisteit lokaas ’n beter manier is om L. humile te beheer as die ander twee mierspesies. Proewe oor voedselvoorkeure het aangedui dat L. humile en C. peringueyi ’n groot voorkeur toon vir suiker, terwyl A. custodiens ’n duidelike voorkeur vir tuna het. Alle mierspesies het egter ’n voorkeur vir nat lokaas (25% suikerwater, 25% heuning, tuna en agar), eerder as droë lokaas (vismeel, sorghumgruis, grondboontjiebotter en hondekos) getoon. Uit hierdie navorsing word afgelei dat lae toksisteit lokaas potensiaal toon in mierbeheer en dat dit produsente ’n meer praktiese, ekonomiese en omgewingsvriendelike metode van mierbeheer kan bied wat met GPB-programme in die wingerd versoenbaar is.

Thesis (MScAgric)--Stellenbosch University, 2011.
ENGLISH ABSTRACT: Shiraz/110R grapevines, growing in a fine sandy loam soil in the Breede River Valley, were subjected to ten different drip irrigation strategies during the 2006/07, 2007/08 and 2008/09 seasons. Grapevines of the control treatment (T1) were irrigated at 30% to 40% plant available water (PAW) depletion throughout the growing season. Grapevines of three treatments were irrigated at 70% to 80% PAW depletion from bud break until véraison (i.e. when ca. 95% of grape berries have changed colour), followed by either irrigation at 30% to 40% PAW depletion (T2) or a continuous deficit irrigation (CDI) strategy (T3) or irrigation at 70% to 80% PAW depletion (T4) during ripening. The CDI strategy was obtained by applying ca. half the volume of water that was applied to the control. This allowed the soil to dry out gradually between physiological stages (i.e. bud break and véraison or véraison and harvest). Grapevines of three further treatments were irrigated at ca. 90% PAW depletion from bud break until véraison, followed by irrigation at 30% to 40% PAW depletion (T5) or a CDI strategy (T6) or irrigation at ca. 90% PAW depletion (T7) during ripening. Grapevines of two treatments were irrigated by means of a CDI strategy from bud break until véraison. For both treatments, the soil water content (SWC) was allowed to dry out gradually until ca. 90% PAW depletion was reached. After véraison, the SWC of the one treatment was maintained at ca. 90% PAW depletion by applying only four small irrigations of three hours each during ripening (T8). The soil of the other treatment, received an irrigation at véraison to refill the SWC to field capacity (T9) followed by the CDI strategy during ripening. Grapevines of the tenth treatment were irrigated at ca. 90% PAW depletion between bud break and véraison followed by a partial profile refill (PPR) strategy during ripening (T10). In order to obtain the PPR strategy, SWC was only maintained between 40% and 60% PAW depletion. Evapotranspiration varied between 3.5 mm/day and 0.1 mm/day for driest and wettest treatments, respectively, during the period between December and February. This was substantially less than the volumes required for full surface irrigation. For irrigations applied at 30% to 40% PAW depletion (T1), 70% to 80% PAW depletion (T4) and ca. 90% PAW depletion (T7) levels throughout the season, crop coefficients for the Penman-Monteith reference evapotranspiration (ETo) were 0.4, 0.2 and 0.1, respectively. Under the given conditions, the different irrigation strategies did not have any effect on root distribution and density. Shoot growth of grapevines exposed to high to severe water deficits in the pre-véraison period stopped before mid December. Shoots of grapevines that were exposed to high or severe water deficits before véraison followed by more frequent irrigation during ripening showed active re-growth. These trends occurred during all the seasons. The level of PAW depletion reflected strongly in the plant water potential in the grapevines. Leaf water potential was influenced by the prevailing atmospheric conditions, whereas stem water potential was less sensitive to atmospheric conditions, but responded more directly to soil water availability. Due to the good relationships between pre-dawn leaf, mid-day leaf, mid-day stem and total diurnal water potential, it was possible to re-classify the water status in terms of previous classifications for these water potentials based on pre-dawn measurements. Water constraints in T1, T2 and T5 grapevines were classed as experiencing no stress, whereas the T7 and T8 ones experienced strong to severe water constraints before harvest. High frequency irrigation strategies during ripening delayed sugar accumulation due to dilution of sugar in the larger berries. Except for the wettest strategy, and where grapevines were subjected to the CDI strategy throughout the season, berry mass increased during ripening, i.e. from véraison to harvest. Water deficits had a negative effect on berry mass, bunch size and yield. Where higher soil water depletion levels were allowed, irrigation strategies had a positive effect on the irrigation water productivity of grapevines compared to the frequently irrigated or CDI strategies. Higher water constraints in grapevines, particularly during ripening, improved sensorial wine colour and enhanced some of the more prominent wine aromas, e.g. spicy and berry. Grapevines that were irrigated at a high frequency during ripening produced wines with diluted character flavours and aromas and inferior overall quality. Under the given conditions, sensorial wine colour and spicy character were the dominant factors in determining overall sensorial wine quality.
AFRIKAANSE OPSOMMING: Shiraz/110R wingerdstokke in ‘n fyn sandleem grond in die Breede Rivier vallei is gedurende die 2006/07, 2007/08 en 2008/09 seisoene met tien verskillende drupbesproeiingstrategieë besproei. Wingerdstokke van die kontrole (B1) is deur die seisoen by 30% to 40% plant beskikbare water (PBW) onttrekking besproei. Drie behandelings is tussen bot en deurslaan (wanneer ca. 95% van die korrels verkleur het) by 70% tot 80% PBW onttrekking besproei, gevolg deur besproeiing by 30% tot 40% PBW onttrekking (B2), ‘n deurlopende tekort besproeiing (DTB) strategie (B3) of besproeiing by 70% tot 80% PBW onttrekking (B4) gedurende rypwording. In die geval van die DTB strategie is ongeveer die helfte van die volume water toegedien wat by die kontrole toegedien is. Laasgenoemde strategie het die grond toegelaat om geleidelik tussen fisiologiese fases (i.e. tussen bot en deurslaan of tussen deurslaan en oes) uit te droog. Drie ander behandelings is by ca. 90% PBW onttrekking tussen bot en deurslaan besproei, gevolg deur besproeiing by 30% tot 40% PBW onttrekking (B5) of ‘n DTB strategie (B6) of besproeiing by ca. 90% PBW onttrekking (B7) gedurende rypwording. Wingerdstokke van twee ander behandelings is d.m.v. ‘n DTB strategie vanaf bot tot deurslaan besproei. Beide behandelings se grondwaterinhoud (GWI) was toegelaat om geleidelik uit te droog tot ca. 90% PBW onttrekking bereik was. Na deurslaan was die GWI van die een behandeling naby ca. 90% PBW onttrekking gehandhaaf deur slegs vier klein besproeiings van drie uur elk gedurende rypwording toe te pas (B8). Die grond van die ander behandeling het tydens deurslaan ‘n besproeiing ontvang om die GWI tot by veldkapasiteit te hervul (B9) en is tydens rypwording weer d.m.v. ‘n DTB strategie besproei. Stokke van die tiende behandeling is tussen bot en deurslaan by ca. 90% PBW onttrekking besproei, gevolg deur besproeiing d.m.v. ‘n gedeeltelike profiel hervul (GPH) strategie tydens rypwording (B10). Om ‘n GPH strategie toe te kon pas, is tussen 40% en 60% PBW ontrekking gehandhaaf. Evapotranspirasie het tussen 3.5 mm/dag en 0.1 mm/dag vir onderskeidelik die natste en droogste behandelings tussen Desember en Februarie gevarieer. Dit was aansienlik laer as volumes wat vir voloppervlak besproeide wingerde benodig word. In die geval van besproeiing by 30% tot 40% PBW onttrekking (B1), 70% tot 80% PBW onttrekking (B4) en ca. 90% PBW onttrekking (B7) deur die loop van die seisoen was die gewasfaktore vir die verwysingverdamping (ETo) 0.4, 0.2 en 0.1 onderskeidelik. Onder die gegewe toestande het die verskillende besproeiingstrategië geen effek op die worteldigtheid en –verspreiding gehad nie. Lootgroei van wingerdstokke wat aan hoë tot baie hoë watertekorte blootgestel was voor deurslaan, het voor middel Desember gestop. Lote van wingerdstokke wat aan hoë tot baie hoë watertekorte voor deurslaan blootgestel is, gevolg deur besproeiing teen ’n hoë frekwensie tydens rypwording, het aktiewe hergroei getoon. Die PBW ontrekkingspeil het sterk in die plantwaterpotensiale van wingerdstokke weerspieël. Blaarwaterpotensiaal is deur heersende klimaatstoestande beïnvloed, terwyl stamwaterpotensiaal minder sensitief teenoor die klimaat was, maar meer direk deur die beskikbaarheid van grondwater beïnvloed is. Vanweë die goeie verband tussen voordagbreek blaar-, mid-dag blaar-, mid-dag stam- en totale daaglikse waterpotensiaal, was dit moontlik om water status van die stokke te her-klassifiseer in terme van vorige vir waterpotensiaalklassifikasies wat op voordagbreek waardes gebasseer is. Waterspanning in B1, B2 en B5 stokke is as geen spanning geklassifiseer, terwyl dié van B7 en B8 voor oes in die hoë tot baie hoë klasse geval het. Hoë frekwensie besproeiing strategieë gedurende rypwording kan suikertoename a.g.v. die groter korrels vertraag. Met die uitsondering van die natste strategie, asook waar stokke volgens die DTB strategie deur die seisoen besproei is, het korrelmassa gedurende rypwording toegeneem. Watertekorte het ’n negatiewe effek op korrelmassa, trosgrootte en produksie gehad. Besproeiingstrategieë waar ’n hoë mate van grondwateronttrekking voor besproeiings toegelaat is, het ’n positiewe effek op die besproeiingwaterproduktiwiteit van wingerd in vergelyking met gereelde besproeiings of ‘n DTB strategie gehad. Watertekorte, veral gedurende rypwording, het ’n verbetering in sensoriese wynkleur en meer prominente wyn aromas, tot gevolg gehad. Besproeiing teen hoë frekwensies gedurende rypwording, het wyne met ’n afgewaterde smaak en aroma karakters asook ’n swak algehele gehalte produseer. Sensoriese wynkleur en spesery karakter die dominante faktore in die bepaling van algehele kwaliteit.

Drosophila suzukii (Matsumura) (Diptera: Drosophila) is an invasive frugivore and has become a significant pest of small fruit, cherry and grape throughout the United States. It may be possible to determine if a Virginia vineyard is at risk of D. suzukii infestation by analyzing the biotic and abiotic factors around each vineyard. This pest is known to utilize a wide range of cultivated and wild host plants. A host plant survey was conducted at four vineyards in the Piedmont Region of Virginia to identify hosts used by D. suzukii around vineyards. The seasonal availability of host plants and adult emergence from them were tracked. Six host plant species of D. suzukii were identified, some available season-long. Monitoring D. suzukii in cultivated crops is crucial for the timing of spray applications. Homemade and commercially available baits and traps were deployed in two vineyards to determine the efficacy and selectivity towards D. suzukii. The homemade and commercially available baits that contained red wine caught the most D. suzukii, but none were exclusively attractive to D. suzukii. Wine grape susceptibility was assessed in laboratory choice and no-choice ovipositional bioassays. Ovipositional susceptibility was determined by measuring the physiological and morphological parameters using six wine grape varieties. More eggs were laid in grapes as penetration force decreased. Penetration force and not skin thickness was the limiting factor for oviposition. Survivorship of eggs laid in intact grapes was analyzed and survivorship to adulthood was dependent upon variety and survivorship usually exceeded 9% survival seen in previous studies. Larval developmental parameters of D. suzukii were affected by grape variety and the density of Z. indianus. D. suzukii mortality was increased in most cases when in competition with Z. indianus, but was less pronounced when reared in Viognier grapes. My Z. indianus oviposition study demonstrated that they will follow injury created by D. suzukii, and then the Z. indianus larvae may outcompete D. suzukii within the berries. These studies greatly improved our understanding of D. suzukii biology and ecology in Virginia vineyards.
Ph. D.

Western Australia (WA) was one of few grape growing regions of the world free from grapevine downy mildew, caused by the oomycete Plasmopara viticola, until two separate detections occurred in 1997 and 1998. The pathogen is now established in all growing regions of the state and growers are required to actively manage the disease due to potential economic loss. The introduction of P. viticola into WA raised a number of questions about the source of the incursion(s), its population structure, ability to survive in a climate not considered optimal for its development and the subsequent economic impact it is having on the WA viticulture industry. Using a number of different detection methods 51 microsatellite markers have been identified for P. viticola. These markers were identified from isolates of European and American populations and had not been tested on Australian isolates. Using three isolates collected from geographically separated locations in Australia all 51 microsatellites were tested for their capacity to detect polymorphism within the Australian populations and the sequences lodged in GenBank. A total of 18 microsatellites were identified showing polymorphism. A total of 413 samples from Australia (286), North America (69), France (32), Brazil (8) and Uruguay (18) were collected as part of a global survey. Both fresh leaf samples and DNA trapped on FTA cards were collected and the populations analysed using 16 of the 18 microsatellites previously identified. The populations were analysed for genetic diversity, mode of reproduction and cryptic P. viticola species present. It was determined the Australian and South American populations more closely relate to the French samples than those of North America, the origin of P. viticola. The only cryptic species discovered outside of North America was P. viticola clade aestivalis. The WA population had the lowest genetic diversity of all populations, likely a result of the more recent introduction of the pathogen and suggests the 1997 and 1998 incursions are linked. Genetic analysis of the WA populations indicate they have a clonal mode of reproduction whereas the American and French populations are sexually reproducing. This is the first record of clonal reproduction within P. viticola and highlights a greater plasticity within the mode of reproduction than previously identified. With relatively mild winters in comparison to northern hemisphere grape production systems it was hypothesised P. viticola could overwinter as mycelium in dormant grape buds in WA. To test this hypothesis a number of field trials and vineyard observations were conducted over two seasons. It was discovered P. viticola can infect green buds, and has the capacity to produce sporangiophores from them, but there is no evidence of any ability to overwinter and produce shoots infected with P. viticola the following season. This finding contrasts long held assumptions about the overwintering ability of P. viticola in dormant grape material. Oospores are considered important for both P. viticola survival and the source of primary infection. However, a survey conducted in the early 2000’s failed to detect oospores in the majority of WA vineyards. Vineyards in the Margaret River and Swan Valley regions of WA having experienced downy mildew infection during the 2014/15 season were assessed for oospores. All vineyards were found to have downy mildew oospores. To determine mating type ratios 11 isolates were co-inoculated on leaf discs and oospores were detected in three crosses including a cross between the same isolate. There is the possibility a single mating type of P. viticola exists in WA with the capacity for secondary homothallism or selfing. Despite P. viticola being present in WA since 1997/98 an economic assessment of the impact of the disease on WA viticulture had not been undertaken. A bioeconomic model was developed linking weather with spread, infection of the disease and production costs and revenue to estimate the cost of P. viticola over time. It was found P. viticola costs the WA viticulture industry AUD $7.3 million per year with cumulative costs over a 30 year period to be AUD $140 million.

Fatores que influenciam a comunidade de morcegos em vinhas: o papel das caraterísticas da paisagem, estruturas naturais e gestão As vinhas são um sistema agrícola muito representado na Europa. Essas áreas apresentam baixos níveis de biodiversidade devido à simplificação da paisagem e ao elevado uso de pesticidas, o que reduz a disponibilidade de insetos e as torna pouco atrativas para morcegos. Nós investigámos o efeito da gestão, do tipo de uso do solo e das estruturas naturais na atividade e riqueza de morcegos em vinhas a duas escalas espaciais: 500 m (escala de vinha) e 1500 m (escala de paisagem). Os resultados demonstraram que as estruturas e os habitats naturais foram mais importantes para os morcegos do que a gestão da vinha. Nós sugerimos que as prioridades de conservação devem ser criar ou manter vegetação ripária e áreas de montado. Essas estruturas naturais são uma componente chave na gestão para promover o uso das vinhas por morcegos, aumentando o seu potencial como reguladores de pragas agrícolas; ABSTRACT: Vineyards are one of most represented agricultural systems in European landscape. These areas can present low biodiversity levels due to simplification of landscape and the high input of pesticides, which reduce insect availability and makes them unattractive for bats. We assessed the effect of farming management, land use type and natural structures on bat activity and species richness in vineyards at two spatial scales: 500 m (vineyard scale) and 1500 m (landscape scale). Our results demonstrate that natural structures and habitats were more important to the bat community than vineyard management. We suggest that conservation priorities should be to create or maintain riparian vegetation – near streams or small dams - and areas of “montados”. These natural structures are important for bat populations within or near vineyards, and a key component of agricultural management to promote bat use of vineyards, enhancing their role as pest regulators.

Mestrado em Viticultura e Enologia - Instituto Superior de Agronomia / Faculdade de Ciências. Universidade do Porto
In order to study the effect of mechanical pruning and the addition of organic amendments to the vineyard in Syrah wine quality, three vineyards from different viticultural areas were tested – Quinta do Côro (Tejo), Quinta do Gradil (Lisboa) and Herdade de Rio Frio (Setúbal). In order to evaluate the influence of the treatments applied the wines were subjected to a physicochemical analysis as well as chromatic characteristics determination, total nitrogen content, mineral and heavy metals and other elements analysis and the tasting panel performed sensory analysis to determine if the differences were perceived. The results show that mechanical pruning led to wines with lower alcohol content, color intensity, total anthocyanin content as well as less tannin power and inferior tannin content. This type of pruning technique also led to lesser accumulation of minerals and lower levels of some heavy metals. In the sensory analysis, the wines from mechanically pruned vines were less appreciated by the tasters receiving worse scores, including lower global appreciation marks. The organic amendment that led to lower overall results in the studied parameters was sewage sludge, it reduced alcoholic content and color intensity as well as total anthocyanin content while grime and the control plots led to better results

Grape root borer, Vitacea polistiformis (Harris), is an oligophagous pest of grapevines in the eastern USA. Neonates must burrow into the soil to find grape roots. In Virginia, larvae feed on roots for ~2 years, then pupate just beneath the soil surface. Emerging adults leave an empty pupal exuviae at the soil surface around the vine base. There was no relationship between weekly captures in pheromone traps and pupal exuviae counts, indicating that exuviae sampling is most appropriate to assess infestations. Exuviae sampling in Virginia vineyards revealed infestations that ranged from light to very heavy. Eighteen biotic and abiotic variables were measured and used in analyses that assessed their relative contributions to differences in exuviae density. Water holding capacity and clay/sand ratio were most strongly associated with pupal exuviae density; these variables were used to develop a model for predicting the extent of infestation of individual vineyards. The spatial distribution of pupal exuviae was characterized using non-spatial and geospatial techniques. Although the non-spatial method (Taylor's Power Law) indicated that exuviae showed an aggregated distribution in all blocks, spatial methods (variograms, SADIE) revealed aggregated distributions only in blocks with ≥ 0.5 pupal exuviae per vine. Independent pupal exuviae samples for population assessment in vineyards can be achieved using sampling points separated by >8.8 m. Combined results from geospatial analyses and the temporal distribution of pupal exuviae within years enabled the development of a practical and quantitative sampling protocol. Bioassays used to measure the behavioral response of larvae to host stimuli revealed that neonates were attracted to grape root volatiles. In soil column bioassays, larvae moved vertically and horizontally over distances of up to 120 cm and apparently perceived the presence of grape roots from a distance of 5 cm in soil. Results are discussed in relation to their potential implications for monitoring and managing grape root borer.
Ph. D.

Mestrado em Engenharia Agronómica - Instituto Superior de Agronomia
This document will be presented in detail, the course of my professional activity started in 1995. This was initially developed at IMAIAA - the Institute for Agricultural Markets and Agro Food Industries - in performing tasks related to the program PAMAF. There followed a brief passage by a private consulting firm with work related to the preparation of applications for obtaining support from the European Union (EU). Finally, my integration into IFADAP - Institute of Finance and Development Support of Agriculture and Fisheries - that with the recast of the Ministry of Agriculture has been integrated with INGA - the National Guarantee Fund, passing its name to IFAP - Institute of Finance for Agriculture and Fisheries, in which I exercised functions of analysis of applications submitted under the Operational Programme for Agriculture and Rural Development (AGRI) and tasks developed to operationalize the Scheme of Restructuring and Conversion of Vineyard (VITIS and RARRV). Parallel to the description of the tasks at the professional level that I have developed will also be presented some issues which are deemed important to mention about the programs in which I was involved, in particular AGRO program, and the support scheme for Restructuring and Conversion of Vineyards, from 2007 to the present. Throughout the entire professional career were being applied the knowledge gained within the degree in Agricultural Economy and Rural Sociology (ISA-UTL), having been developed skills and professional experience in the area of Agrarian Economy and Land Management, from the application of rules and requirements defined in different support programs, as well as by national and Community legislation analysis for the operationalization of these programs.

Thesis (MSc)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Plant-parasitic nematodes, consisting of a wide range of species, can cause severe economic losses in most agricultural food crops. Meloidogyne spp. (root-knot nematodes), Criconemoides xenoplax (ring nematode), Xiphinema index (dagger nematode) and Pratylenchus spp. (lesion nematodes) are some of the economically important plant-parasitic nematodes that pose a threat to viticulture and other perennial crops in South Africa. Worldwide there is ever-increasing pressure on pre-plant synthetic soil fumigants and post-plant nematicides. For sustainable nematode management, it is important to have a holistic approach; taking into consideration cultural, biological and chemical options as part of an integrated management approach. Biofumigation has the potential to fit into such an integrated management system and previous research indicates the positive response on soil-borne diseases, nematodes and weeds. Biofumigation occurs where certain plant species, containing glucosinolates (GSL) in the vacuole of the plant cells, come into contact (after cell maceration), with the enzyme myrosinase (MYR) situated in the cytoplasm of the cell, to form active compounds such as isothiocyanate (ITC). When this green manure is applied to infested soil, the ITC has the potential to have a direct suppressive effect on the soil-borne pathogens and there is also an indirect effect that can be expected after green manure soil amendment, because microbial activity is enhanced in the soil. Brassicas are known to possess GSL and MYR in their cells and thus have the potential to be utilized as biofumigation crops. There are, however, differences in the potential within the Brassicaceae family, based on different types and concentrations of GSL present in the different species. To ensure effective biofumigation it is important to use the correct brassica species and have a good understanding of the factors that have a positive impact on the biofumigation action. Laboratory bioassays were done to determine the potential of different cover crops to suppress Meloidogyne javanica and C. xenoplax, when applied as a green manure. The cover crops used for the bioassays included Oats (Avena sativa cv. Pallinup), White mustard (Sinapis alba cv. Braco), Canola (Brassica napus cv. AV Jade), Caliente 199 (Brassica juncea cv. Caliente 199) and Nemat (Eruca sativa cv. Nemat). The plant material was cut into small pieces and mixed with sterilised soil inoculated with either M. javanica or C. xenoplax. Results from the bioassays showed a significant suppression of M. javanica by the three biofumigation species: White mustard, Caliente 199 and Nemat. These results supported previous research, indicating the nematode suppressing effect due to the biofumigation action of certain brassica crops. Canola did not have the same suppressing impact on the M. javanica and gave comparable results to the control, indicating that Canola is not a good biofumigation crop for M. javanica suppression. In terms of biofumigation effect oats did not differ significantly from the control or the three brassicas: White mustard, Caliente 199 and Nemat. In the bioassays done for C. xenoplax no significant differences were found between the green manure treatments and the control. These results indicate that the different crops tested, including the three well known biofumigation crops, did not suppress the C. xenoplax at the applied biomass concentrations used in the bioassay. Crops can also be classified according to their host status for certain plant parasitic nematodes. Crop host trials were conducted to determine the crop host status of the five different cover crops, to M. javanica and C. xenoplax. The crops were planted in sterilised soil, inoculated with the latter plant-parasitic nematodes and left for 60 days, after which, a root gall index analysis was done for M. javanica and for 85 or 92 days after which C. xenoplax was extracted from the soil. All the crops evaluated had a significantly lower root gall index for M. javanica than the control. Nemat and Oats was classified as poor hosts for M. javanica. A visual inspection of the root systems of all the crops was performed to determine whether M. javanica managed to complete its lifecycle in the different root systems. On all root systems, M. javanica managed to form root galls and produce egg masses, from which (J2) juveniles emerged. This indicates that M. javanica did complete its lifecycle in the different root systems of the crops evaluated and that all the cover crops acted as hosts. The expression of the gall symptoms were, however, less severe on Nemat and Oats, compared to the others. In the C. xenoplax crop host trials, all except the Nemat treatment showed a significant difference, compared to the Tomato treatment, with lower C. xenoplax numbers being present in the other crops. The nematode numbers in the different crops, compared well with the control (only inoculated soil), indicating that the crops did not stimulate the reproduction of C. xenoplax. Canola had the lowest numbers of C. xenoplax present after the growing cycle and Caliente 199 also showed a declining trend. In South Africa, the use of annual cover crops in vineyards is an established soil cultivation practice. In a field study, Oats, White mustard, Canola, Caliente 199 and Nemat were established in a vineyard as cover crops for three growing seasons (2009/10, 2010/11, 2011/12), and evaluated for their biofumigation impact, as well as their host impact on the suppression of certain economically important plant-parasitic nematodes. Two cover crop management practices, namely mechanical incorporation (MC) into the top soil and chemical removal of the cover crop (CC) were applied to the different cover crops. Nematode samples were taken in the work row and in the vine row at different times to determine the nematode status. These periods were April/May, before planting the cover crops, as well as 0, 15, 30 and 60 days after the management practices were performed. The crop biomass, measured as dry matter production (DMP) in tons/ha, differed significantly between the different crops, but also showed substantial increases during the three cover crop growing seasons for most crops. During the three consecutive seasons, Canola (CC) and Caliente 199 (CC) showed a constant reduction in the C. xenoplax population in the vine row based on the 60 day analysis. This trend was also observed for the total plant-parasitic nematode population in the vine row for the three seasons, based on 60 day analysis. The same trend took place during the three-year trial period for all the different sampling periods (0, 15, 30 and 60 days). The results can be attributed to the host status of these crops and not primarily because of the biofumigation effect. Both the Canola (CC) and the Caliente (CC) had a substantial increase in DMP during the three growing seasons that might have played a role in this trend. White mustard (CC and MC) showed a significant increase in the C. xenoplax population in the vine row, over the three year period, based on the 60 day analysis. The same trend was found Nemat (CC) and weeds and nematicide (CC) measured at the same period. A positive result from the Meloidogyne sp. analysis was that there was no significant increase in the Meloidogyne sp. in the vine row during the three growing seasons based on the 60 day analysis. This trend was seen in all the different treatments. The results from this study opens the possibility to apply these cover crops as part of a crop rotation programme without expecting an increase in the Meloidogyne sp. population to occur in the vine row through time.
AFRIKAANSE OPSOMMING: Plantparasitiese nematodes, wat bestaan uit 'n wye verskeidenheid van spesies, kan lei tot ernstige ekonomiese verliese in die meeste landbou gewasse. Meloidogyne spp. (knopwortel nematode), Criconemoides xenoplax (ring nematode), Xiphinema index (dolk nematode) en Pratylenchus spp. (letsel nematode) is van dié belangrikste plantparasitiese nematodes wat 'n bedreiging inhou vir wingerd en ander meerjarige gewasse in Suid-Afrika. Wêreldwyd is daar tans toenemende druk op die uitfasering van voor-plant chemiese grondberoking middels en so ook op nauitplant nematisiede. Vir volhoubare nematode bestuur, is dit belangrik om 'n holistiese benadering te volg, in ag genome kulturele, biologiese en chemiese maatreëls as deel van 'n geïntegreerde benadering. Bioberoking het die potensiaal om deel uit te maak van so 'n geïntegreerde benadering en baie vorige navorsing bevestig hierdie positiewe reaksie, in terme van onderdrukking, wat bioberoking op grond-gedraagde siektes, nematodes en onkruid kan hê. Bioberoking kan beskryf word as die reaksie, wat plaasvind wanneer glukosinolaat (GSL), wat teenwoordig is in die vakuool van die plantselle, in kontak kom met die ensiem mirosinase (MYR), nadat selbreking plaasgevind het en die aktiewe verbinding isothiosianaat (ITC) en ander sekondêre metaboliete gevorm word. Wanneer hierdie groen plantmateriaal in die grond ingewerk word, kan ʼn direkte onderdrukkings effek, as gevolg van die ITC, asook ʼn indirekte onderdrukkings effek as gevolg van die stimulasie van mikrobe aktiwiteit, verwag word. Brassica gewasse is bekend daarvoor dat daar GSL en MYR in die plantselle teenwoordig is en hulle besit dus die potensiaal om ITC te vorm. Daar is egter verskille in hierdie potensiaal binne die Brassicaceae familie, wat gebaseer is op verskillende tipes en konsentrasies GSL. Die keuse van ʼn brassica spesie is dus belangrik, tesame met ʼn verskeidenheid van ander faktore, om optimale bioberoking te verseker. Laboratorium biotoetse is gedoen om die bioberokings effek van verskillende dekgewasse op Meloidogyne javanica en C. xenoplax, wanneer dit aangewend word as groenbemesting, te bevestig. Die dekgewasse wat gebruik is sluit in: Hawer (Avena sativa cv. Pallinup), Wit mosterd (Sinapis alba cv. Braco), Canola (Brassica napus cv. AV Jade), Caliente 199 (Brassica juncea cv. Caliente 199) en Nemat (Eruca sativa cv. Nemat). Die plantmateriaal is fyn opgesny en ingewerk in gesteriliseerde grond wat met onderskeidelik M. javanica en C. xenoplax geïnokuleer is. Resultate van die biotoetse vir M. javanica toon dat die drie gewasse; Wit mosterd, Caliente 199 en Nemat, wat alombekend is vir hul bioberoking potensiaal, ʼn betekenisvolle onderdrukkings op M. javanica tot gevolg gehad het. Hierdie biotoetse ondersteun vorige navorsing, waar effektiewe onderdrukking van sekere Meloidogyne spesies as gevolg van bioberoking verkry is. Die resultate dui ook aan dat Canola nie ʼn goeie opsie is vir effektiewe bioberoking om M. javanica onderdrukking te verkry nie. Die Hawer behandeling het nie betekenisvol van die kontrole of van die ander bioberokings gewasse verskil nie. Daar is geen betekenisvolle verskille verkry tussen die kontrole en die ander gewasse tydens die C. xenoplax biotoetse nie. Die resultate dui aan dat die dekgewasse, insluitende die drie bekende bioberokings gewasse, nie C. xenoplax onderdruk teen die toegediende biomassa konsentrasies nie. Gewasse kan ook geklassifiseer word op grond van hul gasheer status vir sekere nematode. Gasheer toetse is gedoen om die gasheer status van die verskillende dekgewasse vir M. javanica en C. xenoplax te bepaal. Dieselfde vyf verskillende dekgewasse is geplant in grond, wat vooraf onderskeidelik met M. javanica en C. xenoplax geïnokuleer is. Plante is gelos om vir `n spesifieke periode te groei waarna ʼn galindeks evaluasie is gedoen om die gasheer status vir M. javanica te bepaal en ʼn nematode ontleding gedoen is om die gasheer status vir C. xenoplax te bepaal. In die M. javanica gasheer toetse was die galindeks van al die gewasse betekenisvol laer as die kontrole. Nemat kan geklassifiseer word as ʼn swak gasheer vir M. javanica en het betekenisvol minder galle as al die ander gewasse, behalwe die Hawer, waarvan dit nie betekenisvol verskil het nie. Nemat pas dus goed in ʼn dekgewas program waar die doel is om die M. javanica populasie te onderdruk tydens die groei van die gewas. ʼn Visuele inspeksie van die wortelstelsels is ook gedoen ten einde te bepaal of die lewensiklus van M. javanica voltooi is. Wortelgalle en eiersakkies was teenwoordig in die wortels van al die verskillende gewasse en larwes het uit die eiers uitgebroei. Dit dui aan dat M. javanica daarin geslaag het om sy lewenssiklus op al die dekgewasse suksesvol te voltooi. Daar was aansienlik minder eiersakke by Nemat en Hawer; wat hul swak gasheer status bevestig. In die biotoetse vir die gasheerstatus van C. xenoplax het al die gewasse, behalwe Nemat, betekenisvol laer C. xenoplax getalle, in vergelyking met die Tamatie behandeling, tot gevolg gehad. Die nematode getalle was soortgelyk aan die kontrole (slegs geïnokuleerde grond), waar geen gewas in medium geplant is nie, en dui dus aan dat die getalle op die verskillende gewasse nie vermeerder het nie. Die Canola behandeling het die laagste C. xenoplax getalle gehad, gevolg deur Caliente 199. Hierdie gewasse toon dus die meeste potensiaal om aangewend te word in 'n rotasie stelsel of dekgewas program, waar die doel is om die C. xenoplax populasie te onderdruk. In Suid-Afrika is die aanwending van spesifieke eenjarige gewasse, as dekgewasse in wingerde, reeds ʼn standaard praktyk met verskeie voordele. In veldproewe oor ʼn tydperk van drie jaar (2009/10, 2010/11, 2011/12) is Hawer, Wit mosterd, Canola, Caliente 199 en Nemat aangeplant as dekgewasse in ʼn wingerd proefperseel. Die doel van die veldproewe was om die effek van dekgewasse op die plantparasitiese nematodes, wanneer dit aangewend word as bioberokings gewasse, te bepaal. Die gasheer status van die gewasse is ook ondersoek om te bepaal wat die effek sal wees op die nematode getalle. Twee dekgewas bestuurspraktyke is toegepas; meganiese inwerk van die dekgewasse in die bogrond (MC) en chemiese beheer van die dekgewasse (CC) en nematode monsters is op verskillende tye in die werksry en in die wingerdry geneem. Hierdie periodes sluit in April/Mei, voor die vestiging van die dekgewasse en 0, 15, 30 en 60 dae nadat die bestuurspraktyk toegepas is. Die dekgewas se biomassa produksie is, op grond van die droë massa produksie (DMP), in ton/ha gemeet, wat betekenisvol verskil het vir die verskillende dekgewas. Daar het ook `n duidelike toename in DMP plaasgevind oor die drie seisoene vir meeste gewasse. Gedurende die drie jaar periode het die Canola (CC) en Caliente 199 behandelings, gemeet 60 dae na die bestuurspraktyk, ʼn konstante afname getoon in die C. xenoplax in die wingerd ry. Dieselfde tendens het ook voorgekom gedurende hierdie periode in die totale plantparasitiese nematodes teenwoordig in die wingerd ry. Daar is ook ʼn geleidelike afnemende tendens in die C. xenoplax in die wingerd ry, oor die verskillende periodes 0, 15, 30 en 60 dae vir die drie opeenvolgende seisoene, waargeneem. Hierdie resultate kan primêr toegeskryf word aan die gasheer status van die dekgewasse, wat in die gasheer proewe as swak gashere vir C. xenoplax aangetoon is. Nog ʼn faktor wat hier ʼn rol speel is die feit dat beide die Canola (CC) en die Caliente 199 (CC) ʼn toename in DMP van meer as 2 ton, gedurende die drie jaar periode, gehad het; wat op sigself ook ʼn bydraende rol kon speel. Wit mosterd (CC en MC) het oor die drie seisoene ʼn betekenisvolle verhoging in die C. xenoplax populasie tot gevolg gehad, gebaseer op die 60 dae ontleding. Dieselfde tendens is ook opgemerk vir die ander behandelings, onder andere Nemat (CC) en die onkruid en aalwurmdoder (CC) behandeling. ʼn Baie positiewe resultaat na afloop van die drie seisoene is die feit dat daar nie ʼn betekenisvolle verhoging in die Meloidogyne sp. populasie in die wingerdry, op grond van die 60 dae onledings, plaasgevind het nie. Dit was ook die geval vir al die ander behandelings. Hierdie resultate ondersteun die moontlikheid om hierdie bioberokings gewasse deel te maak van ʼn geïntegreerde dekgewas benadering, sonder om in die proses die Meloidogyne sp. in die wingerd ry te verhoog.

The brown marmorated stink bug (BMSB), Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is an invasive insect from Asia that has recently become a major pest of agricultural crops and a nuisance to home and business owners in the Mid-Atlantic U.S. Since 2010, H. halys has been reported in many vineyards in Virginia, but the pest significance in this crop is unknown. Sampling was conducted in four commercial vineyards across Virginia in 2012 and 2013 to study the seasonal phenology and pest status of H. halys in vineyards. Adults moved into vineyards as early as May and laid eggs usually on the undersurface of leaves, but occasionally on the berry or the rachis. Grapevines were an early season reproductive host for H. halys. A vineyard adjacent to a sub-urban area with homes and buildings in proximity had an early season peak of H. halys as compared to vineyards adjacent to woods. However, populations declined sharply in late season due to the possible movement of bugs to more preferable host plants such as soybean and corn. In contrast, H. halys was recorded throughout the grape growing period in a vineyard that was surrounded by forests. Significantly more H. halys were recorded from border than interior section of vineyards. A degree-day model suggested that there were enough degree-days to complete a generation of H. halys in Virginia vineyards. H. halys caused direct injury to the grape berries at veraison and pre-harvest berries. Injury expression in the veraison berry can be described as an appearance of a small necrotic spot at the site of the stylets insertion. The spot gradually increased in size and the berries became deformed. H. halys is an economic pest of raspberry, causing direct injury to the berries. Sampling of stink bugs in raspberry plantings in southwestern Virginia showed that the Euschistus species were the most abundant stink bugs in 2008, 2009, 2011 and 2012. However, H. halys became the most abundant in 2013.
Master of Science in Life Sciences

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on December 28, 2009). Thesis advisor: Dr. Soren C. Larsen. Includes bibliographical references.

Implementation of Sustainable Management Practices at Two California Central Coast Vineyards and Their Effects on Soil Fertility Dawn Michelle Stimson “Sustainable agriculture” has gained increased popularity in recent years. This study was conducted to determine the effects of sustainable management practices on soil fertility at two California Central Coast vineyards. The effects of cover crops (Erosion Control Mix - blando brome [Bromus hordeaceus], hykon rose clover [Trifolium hirtum All.], and zorro annual fescue [Vulpia mourns]), green waste compost (Forest Blend), and reduced tillage on soil fertility were investigated in San Luis Obispo, California on a clay and sandy loam soil. Between the fall 2007 and spring 2008, which had a low precipitation amount (13.3 & 15.6 inches), there was a significant difference (P <0.001 to 0.007) between vineyards in terms of their mean soil nutrient and ratio concentrations. The range of soil values (soil pH, P, K, exchangeable Ca, Mg, and K, OM, Ca/Mg and C/N ratios) was either completely separate or different between Vineyard One and Two. There was almost no significant difference found between treatments and their effects on soil nutrients, exchangeable cations, and ratios. However, there were some noticeable effects on soil nutrients, exchangeable cations and ratios. Soil P and K concentrations increased in most areas (except cover crop/till where it decreased slightly). Soil P increases ranged from 14 to 143% while potassium increases ranged from 9 to 78%. Soil OM increased in all areas at both vineyards (5 to 55%). Ca/Mg ratios increased in some areas between 8 and 43%. C/N ratios increased in all areas between 5 and 85%. Soil type appears to affect soil nutrients, exchangeable cations, and ratios more than sustainable management practices. Keywords: Sustainable, vineyard, and soil nutrients.

The economic impact of frost on agriculture remains a global problem. It is a particular concern for the New Zealand wine industry, where the consequences of an unexpected spring frost can be disastrous. Marlborough is located in the north-eastern corner of the South Island and is the largest grape-growing region in New Zealand. The region is surrounded by complex mountainous terrain that gives rise to extremes of climate, particularly large spatial variations of minimum temperature and the frequent occurrence of spring frost. The high spatial variation of near-surface minimum temperature can lead to under-preparedness among grape growers who rely on accurate frost forecasts as part of their frost mitigation systems. Field campaigns of the 1980’s and 90’s extended the understanding of the physical meteorological processes that affect cooling in complex terrain. More recent modelling efforts continue to refine this knowledge, although much less attention is given to the effects of different cooling processes on near-surface temperature. Agricultural developments in areas of complex terrain would benefit from an increased understanding of the meteorological processes that govern near-surface cooling, as this will help with the local prediction of frost. The spatial variation of near-surface minimum temperatures is first explored by identifying relationships with synoptic weather patterns using the Kidson (2000) synoptic classification scheme. Analysis revealed that Kidson types associated with the largest daily variations in near-surface minimum temperature (T, TNW and H) are not always associated with the occurrence of frost. Frost is more likely to occur during the cooler airflows of Kidson type HW, HNW and SW, or during the settled anticyclonic conditions that follow cooler airflows. The relationship between the spatial variation of near-surface minimum temperature and regional airflow patterns is explored using numerical weather prediction (NWP) modelling. Results indicated that a high σ Tmin around the region is a product of interaction between the region’s complex terrain and ambient meteorology, and it could occur in both settled weather and more dynamic synoptic conditions. A high regional σ Tmin during light ridge top winds could occur as a function of a location’s relative susceptibility to ventilation from thermally-induced drainage winds, and it may also occur as a result of the simultaneous ventilation and stagnation of near-surface air layers as synoptic wind interacts with local topography. The influence of the vertical structure of the nocturnal boundary layer (NBL) on nearsurface minimum temperature was investigated with the University of Canterbury Sonic Detection And Ranging (SODAR). Measurements confirmed the formation of low-level jets (LLJ’s) in the Awatere and Wairau Valleys during settled weather conditions, and that shear-induced turbulence beneath the jets was sufficient to mix warmer air to the surface and increase local temperatures. The process is sufficient to reduce frost risk to some of the region’s upper valleys during clear settled weather. In stronger ridge top winds development of the LLJ’s can be suppressed or eliminated and this was found to reduce shear-induced turbulence near the surface, allowing increased near-surface cooling. While results from this study are of greatest value to the prediction of near-surface minimum temperature and frost in Marlborough, the results could be applied to improved prediction of near-surface minimum temperature in complex terrain around the world. Further research could be directed toward the interaction of synoptic winds with thermally-induced airflows, as the transition zone between these wind systems is believed to govern the temporal and spatial evolution of near-surface stagnation, and this is related to episodes of strong near-surface cooling.

Outbreaks of spider mites (Acari: Tetranychidae) in vineyards have been increasing with the expansion of the industry in Virginia. Only three effective acaricides are registered on grapes and as resistance begins to occur, control options are limited. Biological control of spider mites by inoculative or inundative releases of predatory mites has been tried on a wide range of crops including grapes. This project examined the feasibility of using Neoseiulus fallacis (Acari: Phytoseiidae) as a potential large-scale biological control agent in vineyards. Slide dip bioassays were conducted on N. fallacis to determine the toxicity of insecticides, fungicides and herbicides commonly used on grapes in Virginia. In addition to laboratory experiments, commercially obtained N. fallacis were released in vineyards with spider mite infestations. The populations of both mites were then monitored on a regular basis to determine dispersal and distribution patterns.

Among the insecticides tested in the laboratory bioassays, carbaryl, azinphos-methyl, phosmet, cyhexatin, and pyridaben all caused significantly higher mortality than the control treatment. Fungicides tested were not toxic to the predator, but three herbicides caused high mortality. Glufosinate caused 100% mortality after 24 hours and both oxyfluorfen and paraquat had adverse effects on N. fallacis. The use of materials that were found to be toxic to the predator would not be compatible with inoculative releases of N. fallacis.

Field release results were variable. Three releases were made in 1999 and 2000., Recovery of the predator was low following the releases at two of the sites, probably due to lack of prey. At the third site enough predators were recovered to analyze the spatial distribution of the predator and prey populations. It appears that there is no similar aggregation pattern between the predator and prey at the same point in time although there is an indication of the predator spreading is response to the prey distribution. A more complete season of sampling would give more conclusive evidence of this trend. Although the distribution of the two populations were dissimilar, the predator was present throughout the season and did spread through the entire plot indicating that the predator may be able to colonize the vineyard if it successfully overwinters.

Master of Science

Thesis (MScAgric)--Stellenbosch University, 2003.
ENGLISH ABSTRACT: In the past it was very difficult to visualise the extent and distribution of variability in growth vigour within vineyards. The advancement of remote sensing technology has changed this however, establishing new methods to assess and manage variability. Even though the causes and effects of within-vineyard variability in growth vigour are complex, new technologies offer better ways of monitoring, researching and managing these factors. In addition to the possible benefits of aerial or satellite remote sensing, new methods of mapping soil spatial variability as well as advances in georeferencing technologies supply precision tools to both researchers and producers. The scientific advancement of the technology, however, is currently the most important aspect needed. This is crucial to answer and explore fundamental questions regarding the use of the technology and the interpretation of results within the framework of the plant's observed reaction. Only then can the possible applications in vineyard management be optimised to address the management problems of extensive within-vineyard variation in growth vigour. The choice will always be to use the technology to manage the observed variability in order to limit the negative impacts of a heterogeneous harvest, or to identify the variability and its causes for the implementation of management practices aimed at a more homogenous vineyard and harvest. Whatever the case, extensive research is needed to provide tight correlations between information gathered with new technologies to assess variability and plant status, such as multi- and hyperspectral analysis, and ground-truthed results in the vineyard. Only then will it become evident which methods and analyses would be useful in the drive towards in-depth analysis and management of vineyards within the concept of precision viticulture and its derived advantages. With this in mind, the aim of this study was to establish an experimental model to use remote sensing technologies to identify and classify within vineyard variability with a subsequent analysis of the causes of variability and the effects on the plants. The targeted experimental model was a vineyard with highly heterogeneous above-ground growth. An aerial photograph of the vineyard was studied and manipulated to yield image pixel values used to quantify the degree of variability for different plots, which were chosen according to different plot layouts. Soil conditions were assessed on both a global and plot level, with extremely high pH and low resistance values in the soil in combination with erratic soil preparation practices found to be the main cause of variability. Soil physicochemical condition was also assessed during a soil profile pit study. Significant differences were found between several soil-related parameters measured for the higher and lower vigour levels and a strong correlation was also found between the resistance of a saturated soil paste and the image pixel values. Vegetative measurements also yielded highly significant differences between the vigour levels and confirmed the suitability of the vineyard to study within-vineyard variability. Some of these measurements were also strongly correlated with soil conditions as well as image pixel values. Trunk circumference proved to be an excellent measure for the level of variability, being linked strongly to canopy characteristics, soil conditions as well as the image pixel values. Leaf water potential measurements also yielded significant differences between the vigour levels. Harvest data and wine analyses showed the effect that vigour differences can have on grape composition and wine quality, even though the differences found here were much less than expected. Even though no clear preference was shown between the wines made from the different vigour levels, the lower vigour wine was considered fruitier. The overall quality of both experimental wines was however very high, considering that experimental winemaking techniques has been used. Hyperspectral measurements also confirmed differences between the vigour levels through a narrow-band NOVI (normalised difference vegetation index). It was also possible to show differences in certain biochemical compounds between the vigour levels on both a leaf and canopy level. Wavelength regions corresponding to carotenoid, chlorophyll a and chlorophyll b showed different spectral reactions in the leaves of more stressed (lower vigour) canopies, indicating possibilities for further studies. This study and its results is the first of its kind in the South African wine industry and paves the way for more focussed and in-depth analyses of the use of specifically multiand hyperspectral data to accurately assess within-vineyard vigour variability and the management thereof to yield optimum quality grapes for a specific wine target. Moreover, the approach adopted in this study is also echoed in other international research programs in prominent wine countries. The availability of scientific research regarding the optimal use and limitations of these technologies has the potential to revolutionise production management practices in the next few years in the viticultural industry.
AFRIKAANSE OPSOMMING: In die verlede was dit baie moeilik om die omvang en verspreiding van groeikragvariasie binne 'n wingerd te visualiseer. Die vordering gemaak op die gebied van afstandswaarneming-tegnologie het egter nuwe metodes beskikbaar gestel waardeur hierdie variasie in wingerde gemonitor en bestuur kan word. Selfs al is die oorsake en invloede van binne-wingerd-groeikragvariasie kompleks, verskaf nuwe tegnologieë verbeterde metodes om hierdie variasie te monitor, te bestuur en na te vors. Saam met die moontlike voordele wat lugfoto's en satelliet-afstandswaarneming teweegbring, verskaf nuwe metodes om ruimtelike variasie in grondfaktore te karteer, asook vordering in geoverwysingstegnologie, presisiehulpmiddels aan produsente én navorsers. Die wetenskaplike vordering van dié tegnologie is tans van groot belang. Die belang daarvan is om fundamentele vrae te ondersoek en te beantwoord rakende die gebruik van die tegnologie en die interpretasie van resultate binne die raamwerk van die waargeneemde reaksie in die plant. Dit sal die weg baan vir optimale toepassing van die tegnologie in wingerdbestuur om sodoende die bestuursprobleme wat deur binne-wingerdgroeikragvariasie teweeggebring word, aan te spreek. Die voorkeurkeuse is om dié tegnologie aan te wend om hierdie variasie te bestuur sodat die negatiewe impak van In heterogene oes teengewerk kan word, of om die variasie te identifiseer vir die implementering van bestuurspraktyke gemik op die skep van 'n meer homogene wingerd en oes. Dit is noodsaaklik dat uitgebreide navorsing gedoen word om noue verwantskappe vas te stel tussen inligting wat ingewin is met behulp van nuwe tegnologieë wat die variasie in plantstatus monitor, soos multi- en hiperspektrale analise, en inligting wat op grondvlak ingewin is. Hieruit sal dit duidelik wees watter metodes en analises die doeltreffendste is vir in-diepte analises en die bestuur van wingerde binne die konsep van presisie-wingerdkunde. Met inagneming van hierdie aspekte, was die doel van hierdie studie om 'n eksperimentele model daar te stel waardeur afstandswaarneming-tegnologie gebruik kan word om variasie binne wingerde te identifiseer en te klassifiseer deur analises van die oorsake van hierdie variasie en invloede op die plant. Die geteikende eksperimentele model was 'n wingerd met hoogs heterogene bogrondse groei. 'n Lugfoto van die wingerd is bestudeer en gemanipuleer om pixelwaardes te verskaf wat die graad van variasie vir verskillende eksperimentele plotte, wat aan die hand van verskillende plotuitlegte gekies is, te kwantifiseer. Grondtoestande is bestudeer op 'n globale én plotvlak, met uiters hoë pH en lae weerstande in kombinasie met verkeerde grondvoorbereidingspraktyke, wat geïdentifiseer is as die hoofoorsake vir die hoë vlakke van variasie. Grondfisiese en -chemiese toestand is ook tydens profielgatstudies bestudeer. Betekenisvolle verskille is gevind tussen verskeie grondverwante parameters gemeet vir plotte met onderskeidelik laer en hoër groeikrag, en 'n sterk verwantskap is gevind tussen grondweerstand en pixelwaardes, soos vanaf die lugfoto bepaal. Vegetatiewe metings het ook betekenisvolle verskille tussen die hoër en laer groeikragvlakke opgelewer, wat die geskiktheid van die wingerd vir die studie van binnewingerdvariasie in groeikrag bevestig het. Van hierdie metings was ook nou verwant aan grondtoestande, asook beeldpixelwaardes. Stamomtrek was 'n uitstekende maatstaf vir die vlakke van variasie, aangesien dit nou verwant was aan lowertoestande, grondtoestande, asook beeldpixelwaardes. Blaarwaterpotensiaal-metings het ook betekenisvolle verskille tussen die hoër en laer groeikragvlakke opgelewer. Oesdata en wynanalise het die uitwerking van groekragverskille op druifsamestelling en wynkwaliteit uitgewys, selfs al was die verskille wat gevind is minder as wat verwag is. Hoewel geen duidelike voorkeur tussen die wyne afkomstig van verskillende groeikragvlakke uitgewys kon word nie, was die wyn wat van die laer-groeikrag stokke gemaak was, meer vrugtig. Die algemene kwaliteit van beide wyne was egter baie hoog as in ag geneem word dat eksperimentele wynmaakprosedures gevolg is. Hiperspektrale metings het ook die verskille tussen groeikragvlakke bevestig deur 'n nou-bandwydte NDVI ("normalised difference vegetation index"). Dit was ook moontlik om verskille in sekere biochemiese komponente tussen die groeikragvlakke op 'n blaar- én lowervlak uit te wys. Golflengte-areas ooreenstemmend met karotenoïed, chlorofil a en chlorofil b het verskillende spektrale reaksies in die blare met hoër stresvlak (laer groeikrag) lowers ten toon gestel. Dit het moontlikhede vir verdere navorsing uitgewys. Hierdie studie en die resultate wat verkry is, is die eerste van sy soort in die Suid- Afrikaanse wynbedryf. Dit baan die weg vir meer gefokusde en in-diepte analise van die gebruik van spesifiek multispektrale en hiperspektrale data om binne-wingerdgroekragvariasie akkuraat te monitor en te bestuur met die oog op optimum wynkwaliteit vir 'n spesifieke produkdoelwit. Die aanslag van hierdie navorsing is ook sigbaar in ander prominente wynproduserende lande. Beskikbaarheid van wetenskaplike navorsing rakende die optimale gebruik en tekortkominge van hierdie tegnologieë het die potensiaal om produksiebestuurspraktyke in die wingerdbedryf in die komende jare te revolusionaliseer.