Dissertationen zum Thema „Orchard crop“

Orchards demand large areas of land, thus they are often situated far from major population centres. As a result it is often difficult to obtain the necessary personnel, limiting both growth and productivity. However, if autonomous robots could be integrated into the operation of the orchard, the manpower demand could be reduced. A key problem for any autonomous robot is localisation; how does the robot know where it is? In agriculture robots, the most common approach is to use GPS positioning. However, in an orchard environment, the dense and tall vegetation restricts the usage to large robots that reach above the surroundings. In order to enable the use of smaller robots, it is instead necessary to use a GPS independent system. However, due to the similarity of the environment and the lack of strong recognisable features, it appears unlikely that typical non-GPS solutions will prove successful. Therefore we present a GPS independent localisation system, specifically aimed for orchards, that utilises the inherent structure of the surroundings. Furthermore, we examine and individually evaluate three related sub-problems. The proposed system utilises a 3D point cloud created from a 2D LIDAR and the robot’s movement. First, we show how the data can be segmented into individual trees using a Hidden Semi-Markov Model. Second, we introduce a set of descriptors for describing the geometric characteristics of the individual trees. Third, we present a robust localisation method based on Hidden Markov Models. Finally, we propose a method for detecting segmentation errors when associating new tree measurements with previously measured trees. Evaluation shows that the proposed segmentation method is accurate and yields very few segmentation errors. Furthermore, the introduced descriptors are determined to be consistent and informative enough to allow localisation. Third, we show that the presented localisation method is robust both to noise and segmentation errors. Finally it is shown that a significant majority of all segmentation errors can be detected without falsely labeling correct segmentations as incorrect.
Eftersom fruktodlingar kräver stora markområden är de ofta belägna långt från större befolkningscentra. Detta gör det svårt att finna tillräckligt med arbetskraft och begränsar expansionsmöjligheterna. Genom att integrera autonoma robotar i drivandet av odlingarna skulle arbetet kunna effektiviseras och behovet av arbetskraft minska. Ett nyckelproblem för alla autonoma robotar är lokalisering; hur vet roboten var den är? I jordbruksrobotar är standardlösningen att använda GPS-positionering. Detta är dock problematiskt i fruktodlingar, då den höga och täta vegetationen begränsar användandet till större robotar som når ovanför omgivningen. För att möjliggöra användandet av mindre robotar är det istället nödvändigt att använda ett GPS-oberoende lokaliseringssystem. Detta problematiseras dock av den likartade omgivningen och bristen på distinkta riktpunkter, varför det framstår som osannolikt att existerande standardlösningar kommer fungera i denna omgivning. Därför presenterar vi ett GPS-oberoende lokaliseringssystem, speciellt riktat mot fruktodlingar, som utnyttjar den naturliga strukturen hos omgivningen.Därutöver undersöker vi och utvärderar tre relaterade delproblem. Det föreslagna systemet använder ett 3D-punktmoln skapat av en 2D-LIDAR och robotens rörelse. Först visas hur en dold semi-markovmodell kan användas för att segmentera datasetet i enskilda träd. Därefter introducerar vi ett antal deskriptorer för att beskriva trädens geometriska form. Vi visar därefter hur detta kan kombineras med en dold markovmodell för att skapa ett robust lokaliseringssystem.Slutligen föreslår vi en metod för att detektera segmenteringsfel när nya mätningar av träd associeras med tidigare uppmätta träd. De föreslagna metoderna utvärderas individuellt och visar på goda resultat. Den föreslagna segmenteringsmetoden visas vara noggrann och ge upphov till få segmenteringsfel. Därutöver visas att de introducerade deskriptorerna är tillräckligt konsistenta och informativa för att möjliggöra lokalisering. Ytterligare visas att den presenterade lokaliseringsmetoden är robust både mot brus och segmenteringsfel. Slutligen visas att en signifikant majoritet av alla segmenteringsfel kan detekteras utan att felaktigt beteckna korrekta segmenteringar som inkorrekta.

In response to the changing economy of Kentucky tobacco, producers are seeking an economically viable alternative that can be produced on a similarly small acreage. Blueberries are an emerging crop that satisfy the needs of these producers and are popular with consumers for their flavor and health benefits. In addition to selling the berries, local producers are experiencing much success selling blueberry plants to homeowners and other producers. However, the protocol for propagating specific cultivars under local environmental conditions is unknown. Rooting percentages for producers has been extremely variable. A two year study conducted at Western Kentucky University investigated asexual propagation of four commercially significant cultivars of Vaccinium corymbosum, highbush blueberry, 'Jersey', 'Elliot', 'Bluecrop', and 'Bluejay'. The study was a randomized complete block design with four replications. Cuttings were taken from a producer's field in Metcalfe County and planted in a bed of pure peat under a mist system at the Western Kentucky University Agricultural Research and Education Center. Propagation techniques were designed to closely mimic the systems used by producers. The effect of cutting phenology, rooting hormone, and cutting location along the stem was investigated as they affected rooting percentage, and dry matter mass of leaves, shoots, and roots. Hormones had no effect on rooting or growth of first year cuttings. The greatest rooting percentages and dry mass gain was found in descending order, 'Jersey', 'Elliot', 'Bluecrop', and 'Bluejay'. There was a correlation between location of the cutting and time of the year the cutting was acquired. Basal cuttings performed well early in the season, while apical cuttings performed well later in the season. The effects of four weed management schemes were investigated on berry yield components and new growth in an established orchard of 'Bluecrop' blueberries in Metcalfe County, Kentucky. The experimental design was a randomized complete block with four replications. Plots consisted of six established plants but data was collected on the innermost four. Treatments were weed-free strips 0.609 or 1.828 meters wide within the row, mowing, and an untreated control. Weed-free strips were maintained as necessary with directed sprays of labeled rates of glyphosate, a phloem-mobile, nonselective herbicide. Highly significant differences in new growth were noted during both years from the herbicide-treated plots compared with the non-treated plots. In 2005, highly significant differences were noted within total berry weight and berry weight per plant from the herbicide-treated plots compared with the non-treated plots. In 2006, highly significant differences were noted within total berry numbers, number of clusters per plant, and mean berries per cluster from the herbicide-treated plots compared with the non-treated plots.

In many areas, over half of all diverted water is used for irrigation. Tree fruit crops use a lot of water, but water productivity can be increased using properly-timed precision water stress. In addition to water conservation, increases in water productivity arise from better fruit quality, increased storage life and reductions in pruning and maintenance. One major hurdle to applying precision water stress in orchards is the lack of a reliable, automated method of determining tree water status. However, the influence of physiological characteristics such as rootstock vigor on water productivity are also important. Selecting the most appropriate rootstocks and accurately determining the water status of orchard trees can increase water productivity. Research has shown that some rootstocks can more effectively extract water from soil. In this research, the response to water stress of three different Gisela tart cherry dwarfing rootstocks was compared using a weighing lysimeter system. Gisela 12 and Gisela 3 rootstocks recovered from drought stress more quickly and had higher trunk diameter growth rates than drought-stressed Gisela 5 rootstocks. Two potential methods of determining tree water status were also evaluated. Trunk hydration was measured using electromagnetic sensors and canopy temperature changes were detected using infrared radiometry. Electromagnetic techniques, including time domain reflectometry, can be used to determine the water content of wood. Until recently, the cost of this technology has inhibited its widespread use, but new affordable commercial electromagnetic soil moisture sensors have created renewed interest in this technique. In this research five different types of electromagnetic soil moisture sensors were inserted into the trunks of fruit trees and were monitored over two growing seasons. Maximizing exposure of waveguides to the sapwood increased the response of these sensors to changes in stem water potential. Infrared measurements of canopy temperature have successfully been used with field crops. However, the heterogeneity of orchard canopies makes this technique more difficult in orchards. Here, the efficacy of aiming radiometers at single trees versus at entire orchards was compared over multiple growing seasons. Neither single tree measurements nor whole orchard techniques produced a sufficiently robust signal to recommend them for general use.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
O controle químico, por meio de aplicações de agrotóxicos, destaca-se no combate aos organismos danosos às culturas agrícolas. Devido à toxicidade dos agrotóxicos, qualquer atividade onde se utiliza do controle químico, existe o risco de intoxicação dos trabalhadores e, portanto, há a necessidade de se adotar medidas de segurança. Acredita-se que os trabalhadores não estão convenientemente protegidos do risco de intoxicação com os Equipamentos de Proteção Individual (EPIs) confeccionados no país, por que ainda não têm a eficiência e a vida útil avaliadas em ensaios de laboratório ou de campo. Desta forma, objetivou-se avaliar com o procedimento da norma F 2130 da ASTM a eficiência dos tecidos hidrorrepelentes, em condições de laboratório, dos conjuntos de EPIs Bege Cru (100% algodão) e Camuflado (69% algodão/31% poliamida), usados por trabalhadores em pulverizações de agrotóxicos em culturas de cana-de-açúcar e de citros sem e com 5, 10, 20 e 30 usos e lavagens, e avaliar o uso da combinação da técnica de fotomicrografia dos tecidos com a técnica de análise de imagem quantitativamente, por meio das porcentagens de fibras e de poros dos tecidos para explicar as variações de repelência, retenção e penetração dos agrotóxicos nos materiais dos tecidos sem e após dez usos e lavagens. O tecido do conjunto Camuflado é mais eficiente que o do conjunto Bege Cru na proteção às formulações Supera SC® (hidróxido de cobre) e Roundup Original CS® (glyphosate). A combinação das técnicas de fotomicrografia e de quantificação percentual da porosidade por meio de software é adequada para avaliar a desorganização da estrutura física dos tecidos após usos e lavagens. A estrutura da porosidade do tecido do conjunto Camuflado não é alterada, mas a do tecido Bege Cru é alterada após os dez usos e lavagens em condições de campo
Chemical control by spraying of pesticides, stands in combating organisms that damage agricultural crops. There is the risk of occupational poisoning in any activity where chemistry control is used for prevention and treatment of the agricultural crops, and it is necessary to adopt security measures. It is believed that workers are not satisfactorily protected from the risk of poisoning, because the Personal Protective Equipment (PPE) made in Brazil does not have its efficiency and life cycle adequately evaluated in laboratory or field testing. Stated thus, the present study has aimed to evaluate, by the procedure of F 2130 standard of ASTM, the efficiency of hidrorrepelent clothes, under laboratory conditions, from the sets of EPIs Bege Cru (100% cotton) and Camuflado ( 69% cotton / 31% polyamide), that were used by workers in activities of spraying of sugar cane and citrus crops with and without 5, 10, 20 and 30 uses and laundering, and to evaluate the use of a combination of the photomicrographs technical of clothes with the quantitative technique of image analysis, by the percentages of fibers and pores of the clothes to explain the variations of repellency, retention and penetration of pesticides in the clothes without and after ten uses and washes. It was concluded that the Camuflado cloth is more efficient than the Bege Cru, in both formulations of product crop protection used in laboratory tests with the application of the ASTM standard F2130. The combination of the techniques of photomicrography and quantifying the percentage of porosity by the software is suitable for evaluating disorganization of the physical structure of the clothes after using and washing.It was also concluded through the study that the porosity of Camuflado cloth (cotton/nylon) has not changed its structure after ten washes, however Bege Cru cloth (cotton) was altered

Orientador: Joaquim Gonçalves Machado Neto
Banca: Julio Cesar Galli
Banca: Maurício Leite de Oliveira
Resumo: O controle químico, por meio de aplicações de agrotóxicos, destaca-se no combate aos organismos danosos às culturas agrícolas. Devido à toxicidade dos agrotóxicos, qualquer atividade onde se utiliza do controle químico, existe o risco de intoxicação dos trabalhadores e, portanto, há a necessidade de se adotar medidas de segurança. Acredita-se que os trabalhadores não estão convenientemente protegidos do risco de intoxicação com os Equipamentos de Proteção Individual (EPIs) confeccionados no país, por que ainda não têm a eficiência e a vida útil avaliadas em ensaios de laboratório ou de campo. Desta forma, objetivou-se avaliar com o procedimento da norma F 2130 da ASTM a eficiência dos tecidos hidrorrepelentes, em condições de laboratório, dos conjuntos de EPIs Bege Cru (100% algodão) e Camuflado (69% algodão/31% poliamida), usados por trabalhadores em pulverizações de agrotóxicos em culturas de cana-de-açúcar e de citros sem e com 5, 10, 20 e 30 usos e lavagens, e avaliar o uso da combinação da técnica de fotomicrografia dos tecidos com a técnica de análise de imagem quantitativamente, por meio das porcentagens de fibras e de poros dos tecidos para explicar as variações de repelência, retenção e penetração dos agrotóxicos nos materiais dos tecidos sem e após dez usos e lavagens. O tecido do conjunto Camuflado é mais eficiente que o do conjunto Bege Cru na proteção às formulações Supera SC® (hidróxido de cobre) e Roundup Original CS® (glyphosate). A combinação das técnicas de fotomicrografia e de quantificação percentual da porosidade por meio de software é adequada para avaliar a desorganização da estrutura física dos tecidos após usos e lavagens. A estrutura da porosidade do tecido do conjunto Camuflado não é alterada, mas a do tecido Bege Cru é alterada após os dez usos e lavagens em condições de campo
Abstract: Chemical control by spraying of pesticides, stands in combating organisms that damage agricultural crops. There is the risk of occupational poisoning in any activity where chemistry control is used for prevention and treatment of the agricultural crops, and it is necessary to adopt security measures. It is believed that workers are not satisfactorily protected from the risk of poisoning, because the Personal Protective Equipment (PPE) made in Brazil does not have its efficiency and life cycle adequately evaluated in laboratory or field testing. Stated thus, the present study has aimed to evaluate, by the procedure of F 2130 standard of ASTM, the efficiency of hidrorrepelent clothes, under laboratory conditions, from the sets of EPIs Bege Cru (100% cotton) and Camuflado ( 69% cotton / 31% polyamide), that were used by workers in activities of spraying of sugar cane and citrus crops with and without 5, 10, 20 and 30 uses and laundering, and to evaluate the use of a combination of the photomicrographs technical of clothes with the quantitative technique of image analysis, by the percentages of fibers and pores of the clothes to explain the variations of repellency, retention and penetration of pesticides in the clothes without and after ten uses and washes. It was concluded that the Camuflado cloth is more efficient than the Bege Cru, in both formulations of product crop protection used in laboratory tests with the application of the ASTM standard F2130. The combination of the techniques of photomicrography and quantifying the percentage of porosity by the software is suitable for evaluating disorganization of the physical structure of the clothes after using and washing.It was also concluded through the study that the porosity of Camuflado cloth (cotton/nylon) has not changed its structure after ten washes, however Bege Cru cloth (cotton) was altered
Mestre

Fruit growers in Utah and other areas across the Intermountain West are faced with growing production challenges stemming from declining soil quality and water resources. Population growth presents challenges in terms of the cost and availability of land, but also presents opportunities in the form of new marketing options such as organic fruit. Few certified organic fruit orchards are operating in Utah currently, which is attributed to a lack of locally tested and adapted organic management practices. An organic peach orchard trial evaluated the effectiveness of different organic management approaches to enhance soil quality and conserve water without compromise to fruit tree growth and fertility. Two tree-row treatments: ‘straw mulch' (Triticum aestivum L.) and ‘living mulch’ (Lobularia maritima (L.) Desv.) were tested in combination with two alleyway groundcovers: ‘grass’ (Festuca rubra L. with Lolium perenne L.) and a legume, ‘Birdsfoot trefoil’ (Lotus corniculatus L.). The novel systems were compared with industry standards, tillage and weed fabric tree-rows with grass alleyways. Trefoil alleyway biomass deposited into tree-rows contributed an estimated 6.24 kg biomass and 0.21 kg total N/tree annually. Trefoil treatments had higher levels of organic carbon (C) and nitrogen (N), inorganic N, microbial biomass and enzyme activities, suggesting trefoil alleyways enhanced soil nutrient cycling, as well as C and N reserves in comparison to grass and tillage treatments. A functional gene array analysis was conducted to describe the mechanisms, microbial functional composition and diversity underlying the observed soil processes, however few differences were detected in soil community structure between soils under different orchard floor management. Significantly lower leaf δ15N in trees grown with trefoil compared to grass, and an association between root biomass, diameter and trunk cross-sectional area (TCSA) suggests nitrogen sources derived from the trefoil groundcover contributed to improved fruit tree vigor. Few differences resulted among orchard treatments for water use (mm/week). Trends indicated slightly higher water use in trefoil over grass, but not enough to offset observed soil quality and tree growth benefits. These findings suggest, trefoil alleyways may provide ecological benefits such as improved soil quality and efficient nutrient cycling, without substantial increases in water use.

Crop production is a significant contributor to greenhouse gas emissions because cropping inputs and cultivation lead to the formation of nitrous oxide (N2O) in soils. This research measured the baseline N2O emissions from apple, cherry, processing tomato and babyleaf spinach production in Australia and assessed the impacts of crop management practices on these emissions. Nitrous oxide emissions were measured using static chambers, and the impact of management practices including crop residue mulches, cover crops, composts and irrigation management on emissions was assessed; and, the data compared to estimated emissions calculated using the Intergovernmental Panel on Climate Change (IPCC) and the Cool Farm Tool (CFT) models. In Vietnam N2O emissions were measured in preliminary studies on vegetables crops, and the effectiveness of technical extension guidelines to mitigate N2O emissions were analysed. Average N2O emissions from fruit orchards and vegetable crops in Australia were low (less than 10 g N2O-N ha-1 day-1), while the emissions for choy sum, mustard and cabbage crops in Vietnam were higher, ranging from 12 g to 40 g N2O-N ha-1 day-1. Compost and lucerne straw additions increased N2O emissions in orchards while wheat straw mulch or bare soils did not. Sub-surface drip irrigation, legumes and ryegrass cover crops and low nitrogen fertiliser inputs were identified as potential strategies for mitigating N2O emissions in baby leaf spinach and processing tomatoes. The CFT and IPCC default values tended to overestimate measured N2O emissions. Technical guidelines for vegetable production in Vietnam focus on economic benefits rather than managing greenhouse gas emissions. Avoiding overuse of urea, using NPK, organic, slow-release urea fertilisers, and establishing permanent beds with small tractors were identified and ways to reduce GHG emissions in Vietnam.

Unlike other rosaceous fruit crops such as apple and cherry, commercial raspberry cultivars are largely self-fertile and can set fruit in the absence of pollinators. However, their floral morphology often prevents complete self-pollaintion. Incomplete pollination yields unmarketable small or crumbly fruits. Insect visitation is therefore essential to maximizing raspberry yield. Honey bees are typically used to pollinate commercial raspberry; however, escalating prices for hive rentals coupled with increasing acreage encourage evaluation of other manageable pollinators. Bumble bees (Bombus spp.) and several mason bees (Osmia spp.) are promising raspberry pollinators. Five bee species were evaluated and compared for their single-visit pollination efficacies on raspberry. From this a pollinator effectiveness index was created and an estimation of the minimum number of visits required to maximize fruit set was calculated. This estimation was then experimentally verified. Finally, in an attempt to synchronize their brief activity period with raspberry bloom, winter management options aimed at delaying the emergence of the mason bee, O. lignaria, were investigated. All five bee species proved excellent pollinators of raspberry. None of the alternative manageable species greatly outperformed honey bees. For this reason honey bees remain the most economical and practical option for open-field raspberry pollination. The adoption of alternative manageable bees could still be justified in other production systems, such as high-tunnel or greenhouse grown raspberry, which hamper honey bees’ ability to forage effectively. The pollinator effectiveness score for honey bees suggested that as few as two visits can achieve maximum fruit set. This estimate was confirmed through experimentation on three different red raspberry cultivars. For two of these cultivars, just one visit yielded drupelet counts similar to openly-pollinated flowers. This information can be used to help refine stocking density estimates for honey bees on raspberry. Wintering bees at 0° or -3° C rather than 4° C effectively delayed emergence of O. lignaria by more than a month without any impact on post-winter performance. These results suggest winter storage at near freezing temperatures is a viable management option for the use of O. lignaria with later-blooming crops.

Depredation to crops and orchards is a problem for agricultural producers in many states where big game are in close proximity to land used for ag-production. Heavy snowfall has created a serious big game depredation in Utah in recent years . Heavy snowfall covers big game feed during winter months, which creates a serious demand on cultivated land to maintain the big game herds at current levels. Many operators believe that current big game herd sizes are too large available feed, and should be reduced to prevent damage to agricultural production. Many big game managers believe otherwise. This study looked at losses to ag-producers in the past five years (1981-1986) in an effort to determine the location and magnitude of losses to big game depredation. A questionnaire, developed to survey damaged ag-producers, separated big game depredation into four categories: 1) unharvested or standing crops, 2) feed or harvested crops, 3) orchards and 4) range or rangelands. Each category was broken down by type of damage; 1) consumption, 2) spoilage (for feed), 3) trampling (for standing crops and rangelands), 4) fence damage, 5) nuisance costs and 6) permanent damage (damage affecting more than one year's revenue from the enterprise). The questionnaire also sought information concerning State assistance to agoperators for damage received. There were also questions concerning income from hunting club leases and private trespass permit sales, which provide income from big game sources. Estimates were made of dollar damages in the categories noted above. All information was summarized by county and in total. Tables of information collected are provided in the appendix. Comparisons were made between mean losses and mean income (hunting club leases, private trespass permits and/or state assistance) using simple large sample tests of hypotheses. Permanent damage was also evaluated for one orchard in which deer had abused the orchard to the point where it had to be removed and replanted. The assertion was made that the depredation created a loss of revenue over a five year period, and losses were evaluated using capital budgeting techniques. Respondents comments, which did not lend themselves to quantitative evaluation, were also summarized.

Philosophiae Doctor - PhD
Water availability and climate related issues are some of the greatest crop production risks to irrigated agriculture in arid regions. In South Africa, for example, the increasing frequency and severity of droughts related to climate change and the growing competition for limited water resources among different users threaten the sustainability and growth of irrigated agriculture, especially the water-intensive fruit industry. Major fruit such as apples (Malus domestica Borkh) are produced entirely under irrigation in South Africa. As a result, there has been considerable research to accurately quantify the water requirements of fruit tree orchards in order to maximize water productivity.

Weed control is typically achieved by broadcast spraying postemergence herbicides on the entire orchard floor which wastes chemical by spraying bare ground. Growers can account for spatial variation in weed density and only spray weedy areas instead of applying herbicide to entire fields by using the automatic spot-sprayer, WeedSeeker sprayer. We conducted field experiments in flood- and microsprinikler-irrigated lemon orchards, and flood- and sprinkler-irrigated pecan orchards to measure the amount of herbicide applied, weed control, tree yield, and the economic value of adopting the WeedSeeker sprayer compared to conventional boom spray technology. The WeedSeeker sprayer reduced cumulative herbicide use by at least 36% compared to the conventional boom sprayer at all sites. Weed control obtained using the WeedSeeker sprayer was usually similar to the conventional boom sprayer. There were no effects of the treatments on yield at any location. The partial budget analysis, used to determine the economic value of adopting the technology, showed that as the area of the orchard and the cost of the herbicide increased, the time to recover the initial investment in the WeedSeeker sprayer decreased. The investment in the technology can typically be recovered in less than five years in Arizona lemon and pecan orchards.We also conducted greenhouse experiments to determine the effect of various sensitivity settings and leaf area on the operational efficiency of the WeedSeeker sprayer. The WeedSeeker sprayer did not detect and spray all broadleaf and monocot plants unless a sensitive setting was used. The WeedSeeker sprayer was more efficient when detecting broadleaf plants compared to monocot plants. Our results indicate that operating the WeedSeeker sprayer using a sensitive setting (sensitivity level 2) will result in the most efficient detection of weeds.Finally, field studies were conducted in a non-bearing pecan orchard to evaluate weed management systems using various postemergence and preemergence herbicides. Most postemergence herbicides controlled the weed species present in the orchard. Tank mixing the herbicides generally resulted in greater control compared to applying them alone. All preemergence herbicides reduced the weed emergence compared to not using a preemergence herbicide. No pecan tree damage was observed in any treatment.

L'expansion des zones agricoles a conduit à la perte de biodiversité due à la réduction des habitats naturels et semi-naturels dans les paysages agricoles. Avec l'augmentation de la production agricole dans le monde, des techniques écologiquement rationnelles sont de plus en plus discutées qui permettent une gestion durable des habitats environnants. Les effets de ces habitats sur la population des insectes nuisibles et de leurs ennemis naturels sont encore mal connus. L'objectif de cette thèse était de comprendre les effets des environnements naturels et semi-naturels sur la population des insectes nuisibles et des ennemis naturels dans les régions tropicales (Brésil) et tempérées (France). Au Brésil (chapitre II), on a évalué l'effet de la distance des fragments sur la population de fourmis prédatrices et omnivores dans la canne à sucre. Les résultats montrent que la richesse en espèces diminue avec la distance des fragments forestiers et que la prédominance des espèces Dorymyrmex bruneus et Pheidole oxyops augmente. Des espèces de fourmis colonisant les champs de canne à sucre ont également été trouvées dans des fragments forestiers, ce qui suggère que ces derniers habitats sont des refuges pour les espèces de fourmis prédatrices pendant les périodes de perturbation comme la récolte de la canne à sucre ou le travail du sol. Cela a été confirmé par des différences plus fortes dans les communautés de fourmis après la récolte de la canne à sucre (saison sèche) que quatre mois plus tard / (saison des pluies) quand l'absence de perturbation a permis la re-lonosiation par les fourmis. Il y avait aussi une différence dans la richesse des espèces de fourmis entre les différents types de fragments (vallées fluviales et plaines). En France, on a évalué l'effet des bandes de fleurs sauvages, de la végétation spontanée et des bandes d'herbe sur la communauté des ennemis naturels et la régulation du puceron de la pomme rosâtre Dysaphis plantaginaea (chapitre III). En ce qui concerne les principaux ennemis naturels, nos résultats ont montré une densité plus élevée de hoverflies par rapport à d'autres types de bande, mais aucune différence pour les coccinelles (coccinelidae). Cependant, aucune différence de densité naturelle de l'ennemi n'a été observée à l'intérieur des vergers. Le nombre de pucerons était plus élevé près des marges, ce qui suggère que la colonisation à partir des bandes marginales peut contrecarrer les effets régulateurs positifs des ennemis naturels. Les effets positifs de la végétation de la marge de bande sur la régulation des ravageurs de la pomme nécessitent un mouvement d'ennemis naturels dans le verger. Nous avons testé les mouvements des prédateurs généralistes en étiquetant les bandes de marge avec des protéines d'oeufs et nous avons vérifié si elles se nourrissaient d'insectes nuisibles en utilisant l'analyse de marqueurs génétiques des gènes de papillon (Cydia pomonella) à l'intérieur des prédateurs (chapitre IV). Les résultats ont montré que peu de personnes se déplaçaient des marges de champ dans le verger. Cependant, 25% des prédateurs capturés se nourrissaient de C. pomonella indiquant encore un haut niveau de régulation naturelle. En conclusion, le mouvement limité des prédateurs à partir des bandes de marges dans les vergers peut expliquer l'absence de différences entre les traitements de bandes dans la régulation des ravageurs du verger (pucerons). Les habitats naturels et semi-naturels peuvent contribuer à la lutte contre les ravageurs en marge des cultures, mais dans les vergers de pommiers cet effet a fortement diminué avec la distance
The expansion of agricultural areas has led to the loss of biodiversity due to the reduction of natural and semi-natural habitats in agricultural landscapes. With the increase of agricultural production in the world, environmentally sound techniques are increasingly discussed that allow a sustainable management of surrounding habitats. The effects of these habitats on the population of insect pests and their natural enemies are still poorly understood. The objective of this thesis was to understand the effects of natural and semi-natural environments on the population of insect pests and natural enemies in tropical (Brazil) and temperate (France) regions. In Brazil (Chapter II) the effect of the distance of fragments on the population of predatory and omnivorous ants in sugarcane was evaluated. The results showed that the species richness decrease with distance from forest fragments and that the dominance of the species Dorymyrmex bruneus and Pheidole oxyops increase. Ant species colonizing sugarcane fields were also found in forest fragments suggesting that the latter habitats are shelters for predatory ant species during periods of disturbance such as sugarcane harvest or soil tillage. This was confirmed by stronger differences in ant communities after sugarcane harvest (dry season) than four months later /(rainy season) when absence of disturbance allowed re-colonization by ants. There was also a difference in the richness of ant species between different fragment types (river valleys and plateaus). In France, the effect of wildflower strips, spontaneous vegetation and grass strips on the community of natural enemies and the regulation of the rosy apple aphid Dysaphis plantaginaea (Chapter III) were evaluated. Concerning major natural enemies, our results showed a higher density of hoverflies compared with other strip types but no difference for ladybirds (coccinelidae). No differences in natural enemy densities were observed inside orchards. Aphid number was higher close to the margins suggesting that colonization from margin strips may counteract positive regulatory effects of natural enemies. Positive effects of strip margin vegetation on regulation of apple pests require a movement of natural enemies into the orchard. We tested the movements of generalist predators by labelling margin strips with egg protein and we checked whether they fed on pest insects using genetic marker analysis of codling (Cydia pomonella) moth genes inside predators (chapter IV). The results showed that few individuals were moving from the field margins into the orchard. However, 25% of the captured predators fed on C. pomonella still indicating a high level of natural regulation. In conclusion, the limited movement of predators from margin strips into orchards may explain the absence of differences between strip treatments in orchard pest regulation (aphids). Natural and semi-natural habitats can contribute to pest control at the margins of crops, but in apple orchards this effect strongly decreased with distance

The object of the research project was to propose and develop innovative theoretical methods for evaluating mass and energy exchange processes within one of the most relevant crop of the agricultural Sicilian context. The study was conceived as a long monitoring program of micrometeorological features of the study orange orchard at different spatial scales (plant, orchard, farm). Different micrometeorological methods, mainly based on Surface Renewal theory, were studied and tested, in order to provide reliable and low cost estimates of sensible heat fluxes within the plant-atmosphere system. Micrometeorological techniques were integrated with in situ measurements of transpiration by up-scaled sap flow techniques, physiological plant features and microclimatic characteristics of the study area. Derived actual crop evapotranspiration fluxes, by means of the resolution of the energy balance equation opportunely corrected for closure, and crop coefficient values were analyzed. All these efforts may contribute to address irrigation water scheduling towards water saving measures.

Este estudio constituye una importante fuente de información sobre el potencial de los sírfidos depredadores (Diptera: Syrphidae, Syrphinae) como agentes biológicos para el control de plagas en cultivos agrícolas en Venezuela. Las larvas de los Syrphidae presentan una morfología muy variada y poseen una gran diversidad de modos de vida. La mayor parte de los representantes de la subfamilia Syrphinae, son depredadores de una amplia gama de hemípteros de cuerpo blando aunque también pueden alimentarse de otros artrópodos. Las principales presas de los sírfidos depredadores son los áfidos o pulgones (Aphididae), escamas (Coccoidea), aleuródidos (Aleyrodidae) y trips (Thripidae). Para la realización de la presente Tesis doctoral se realizó un muestreo en los principales cultivos del estado Lara y se revisó la colección del Museo de Entomología José M. Osorio (MJMO = UCOB, según el Biodiversity Collections Index) de la Universidad Centroccidental "Lisandro Alvarado". También se revisaron ejemplares de la colección del Museo del Instituto de Zoología Agrícola (MIZA) de la Universidad Central de Venezuela. Entre los resultados de la tesis, se presenta una base de datos con los sírfidos depredadores estudiados con un total de 2571 ejemplares agrupados en 11 géneros y 59 especies. Del total de especies estudiadas, al menos se identificaron 15 nuevos taxa para la ciencia. Adicionalmente, se realizó un inventario de las presas y plantas asociadas a cada especie de Syrphidae depredador. Se reportaron nuevas especies de presas y plantas asociadas que aumentan de manera significativa el conocimiento de estas relaciones conocidas hasta la fecha en Venezuela. Como ejemplo, para A. exotica, se indican 6 nuevas presas y 23 plantas hospedantes; para P. clavatus se registran 7 nuevas plantas hospedantes. Por último, destacar 26 nuevos registros de presas relacionadas con el género Ocyptamus sobre 33 especies de plantas asociadas, presentando la mayor diversidad de presas de todos los sírfidos estudiados. En función de los resultados obtenidos en el muestreo se procedió al estudio del potencial biológico de Allograpta exotica, Pseudodoros clavatus y Ocyptamus dimidiatus, utilizando como presa al áfido de las leguminosas, Aphis craccivora en condiciones de laboratorio. Los parámetros biológicos de la especie (A. exotica) fueron estudiados en detalle. Las curvas de respuesta funcional de A. exotica se ajustaron mejor y mostraron el valor más alto de R2 para el modelo Polinomial indicando una fuerte correlación entre el aumento de áfidos depredados por A. exotica y las diferentes densidades ofrecidas de A. craccivora. El coeficiente de determinación para el modelo de Holling sugiere que A. exotica responde al Tipo de curva II. De manera complementaria a los estudios anteriores, se procedió al análisis de la morfología preimaginal de los géneros Allograpta, Pseudodoros y Ocyptamus. Además, se estudió la morfología preimaginal de Eosalpingogaster umbra Mengual y Thompson, Salpingogaster nigra Schiner, Leucopodella sp. nov. y xanthandrus bucephalus (wiedemann) aportando las primeras informaciones conocidas sobre su morfología preimaginal y las implicaciones sistemáticas derivadas. Se describen por vez primera el pupario, la larva madura (L-3) y la quetotaxia de O. dimidiatus y O. gastrostactus. También se describen los puparios de Ocyptamus funebris, O. norina, O. phaeopterus O. stenogaster, Ocyptamus lividus, O. tristani y Ocyptamus sp.nov aff. attenuatus. Por último se incluye una clave de identificación diagnóstica de las especies de Ocyptamus cuya morfología preimaginal ha sido analizada en esta memoria.
Consejo de Desarrollo Científico, Humanístico y Tecnológico de la Universidad Centroccidental Lisandro Alvarado (CDCHT-UCLA), financiamiento al proyecto de Tesis Doctoral 003-DAG-2007.

This thesis is a comparative study of carbon and nitrogen flux dynamics following sole and combined application of mango leaf litter mulch and inorganic fertiliser in highly weathered tropical mango orchard soils. In doing so, the thesis investigated litter decomposition dynamics and litter carbon mass balance and provided baseline datasets of seasonal and annual reactive nitrogen losses (through hydrological and gaseous pathways) under the tropical environmental conditions of Northern Territory Australia.

碩士
國立屏東科技大學
水土保持系
92
The purpose of this study was to determine the effects of different crop covering and mulching practices on soil properities, soil and water and nutrient losses and on growth of main crops in sloping orchards. Two experimental plots, at Fengshan Horticultural Experimental Station and planted with litchi and mango and treated with various cover crops and mulching practices, have been monitored from 1987 to 2002. The results obtained are as follows: 1. Crop covering by grasses significantly reduces soil, water and nutrent losses and improves soil physical and chemical properties than the clean cultivation. Bahia grass and centipede grass are among the best but no significant difference was observed. 2. Crop covering by bahia grass or centipede grass on hillside ditched slopes similar to the experimental plots can effectively control soil, water and nutrient losses and improve soil properities. But bahia grass covering affects the growth of fruit trees. To attain the effects of centipede grass, the plots ground cover should be maintained. 3. On steeper slopes, centipede grass is significantly less effective than either treatment of bahia grass covering and bahia grass strip covering and mulching in terms of soil, water and nutrient losses and soil property improvement. 4. Bahia grass strip covering and mulching on hillside ditched slopes similar to the experimental plots can effectively control soil, water and nutrient losses, improve soil properties and enhance growth of fruit trees. This practice is suitable for steep orchards.

Orchard profitability and sustainability are largely dependent on the proportion of crop that can be marketed as first quality (pack-out). While pack-out is directly related to average fruit quality, the visual components of quality, i.e. colour, size and skin finish, predominantly determine whether a premium price is achieved. Fruit quality is the result of a complex interaction of management and environmental factors. By understanding the impact of environment, culture, harvesting, handling and storage on fruit quality, growers should be able to improve both average quality in their crop as well as improving the proportion of fruit in the highest quality grade. Whilst management practices such as pruning, shading, and crop regulation methods have been widely studied as individual or isolated issues, the role of each in commercial orchard systems is less well understood. From the literature, it was concluded that available information was conflicting in relation to the impact of practices such as pruning and chemical thinning on fruit quality, while the impact of crop load on fruit quality was often confounded by the effect of chemicals used to manage crop load. The impact of time and level of pruning, protection of fruit from direct sunlight, and crop regulation was studied in a series of field experiments in orchards managed to local commercial standards. An examination of level and time of fruit thinning on a range of cultivars is included along with an assessment of two new generation blossom thinners (desiccants). As these desiccants frequently cause varying degrees of foliar damage, the impact of various levels of simulated foliar damage on both crop load and fruit quality was assessed. The blossom desiccant ammonium thiosulphate (ATS) showed positive effects on fruit quality with an increase in both fruit firmness and sugar content. Potassium thiosulphate showed similar promise to ATS in terms of both fruit quality and as a method of managing crop load. Low levels of foliar damage during the flowering period had little effect on fruit quality but, where 75% or more of the leaf surface was lost, fruit quality was affected and fruit set was reduced. This study confirmed that loss of leaf area affects fruit quality but it also showed differences between the two cultivars studied. It has been demonstrated by this study that both the degree and timing of pruning can affect crop load, fruit size, and fruit quality. Pruning during the dormant winter period resulted in better fruit quality than when pruning was delayed until after fruit set. Summer pruning adversely affected fruit size, sugar content and fruit skin finish. Both crop load and fruit size were reduced by overall shading of trees during early fruit development. Covering individual fruit with commercial paper ‘apple bags’ improved fruit skin finish with the effectiveness related to time of application. The earlier in the season fruit is covered, the more likely that fruit skin damage will be prevented. Early thinning had a positive effect on fruit quality, resulting in larger, firmer fruit with higher sugar levels. Evidence also showed that early thinning caused fruit to mature earlier than later thinning. In addition, positive relationships were demonstrated between fruit sugar content and weight, between fruit firmness and weight, and between fruit sugar content and fruit firmness. These relationships have not been reported previously and demonstrate that early thinning is a valuable tool in improving fruit quality. Overall results were consistent with the established view that major aspects of fruit quality are determined in the first few weeks of development when cell division is dependent on carbohydrates derived from storage or limited current photosynthate. This study has demonstrated that by increasing awareness of the impact of orchard management practices on fruit quality and making appropriate adjustments, the base level of fruit pack-out can be increased with minimal or no additional cost to growers.

In Washington State the Pandemis leafroller, Pandemis pyrusana (Kerefoll) and obliquebanded leafroller, Choristoneura rosaceana (Harris) are serious pests in orchards in which mating disruption is used to control codling moth, Cydia pomenella. Resistance to organophosphate insecticides exacerbates the problem. Additionally, many question the dependence on insecticides and call for ecologically-based pest management. Parasitoid and predator conservation and augmentation via insecticide reduction and habitat manipulation are tactics proposed to achieve biological control. The objectives of these studies were to: 1) evaluate and compare development of leafroller populations and their biological control by parasitoids in an apple orchard with either a grass or alfalfa cover and in which no insecticides were used; 2) evaluate the influence of cover crops on the general orchard arthropod population in an orchard managed without insecticides; 3) evaluate the use of alfalfa as an orchard cover crop on fruit tree growth and development; and 4) conduct initial testing of strategies for augmenting the leafroller parasitoid Colpoclypeous florus. Experiments were conducted in an East Wenatchee, Washington apple orchard, over four years. Plots were approximately 0.5 ha in size and were sown to either grass cover or alfalfa. Insecticide applications were eliminated. In the absence of broad-spectrum insecticides leafroller populations initially rose to high levels and then dramatically declined. A granulovirus may have been primarily responsible for the decline. Leafroller parasitoids also contributed to leafroller biological control though not extensively. There were no differences in leafroller populations between ground cover treatments. In some instances parasitism was slightly greater in the alfalfa cover plots but this did not seem of any practical significance. Six species were identified in the parasitoid complex. No secondary arthropod pest achieved pest status in either ground cover during the study. Codling moth however became a serious problem in year four. Attempts to augment C. floras populations by seeding parasitized Ancylis comptana fragaria failed. Attempts to establish Xenotemna pallorana on the alfalfa cover to serve as an alternate host for C. floras were likewise unsuccessful. Alfalfa as a cover crop imposed no adverse effects on tree growth and development during the duration of these studies.
Land and Food Systems, Faculty of
Graduate

Spiders are naturally occurring predators of insects in agroecosystems. The use of broad spectrum pesticides in agriculture is likely to disrupted spider communities and have a negative impact on their role as biocontrollers. The overall abundance, the species richness, diversity and guild structure of spiders in tropical mango orchards in central Queensland were investigated in this study. Experiments were performed to assess the potential of spiders as natural predators to pest insects in mango orchards. The effects of pesticides on the spider communities were assessed to establish the extent to which the communities were disrupted and the extent of recovery from this type of disturbance. The short term (acute) and long term (chronic) effects were investigated. The spiders in unsprayed mango orchards were relatively high in abundance, species richness and species diversity. Spiders were present in significant numbers at all sampling times,both day and at night, and during all seasons. The results suggest that spiders do not capture large numbers of prey. However spider exhibit a diversity of capturing techniques so that they capture a variety of insects. The most common guild was the orb-weavers. The spider abundance and diversity four days after spraying with methidathion suggested that recovery of spider after disruption such as the use of pesticides' occurs quickly. Presumably this recovery occurs due to spiders moving into the orchard from surrounding bush land. The long term use of pesticide does appear to disrupt the community and as evidenced by decreases in the abundance, species richness and diversity of spiders. While it is unlikely that pesticide usage will be eliminated in most commercial mango orchards, this study demonstrates that spiders are potentially important biocontrollers and that they are adversely affected by pesticide use. In the longer term, it will be desirable to develop IPM strategies to minimise pesticide use and maximise the role of spiders as biocontrollers. Such strategies will depend on studies such as this one and extensions of it.

Department of Ecology and Resource Management
PhDENV
The main aim of the research was to contribute means for converting conventional, high-input production systems to more sustainable ecological systems, thereby improving the sustainability of macadamia production and ultimately contributing to food security. This was achieved by a) investigating the potential use of cover crops and compost to enhance soil quality in macadamia orchards and b) investigating the potential use of use of cover crops and orchard heterogeneity to control stinkbug pests that target macadamia crops. Field experiments were conducted in three phases: phase one tested the potential of six cover crops for crop protection (as trap crops) and simultaneously for soil restoration or fertility enhancement purposes in macadamia orchards. Phase two repeated the trials of phase one (both soil restoration and trap crops) but with modifications to both categories. Soil restoration treatments were conducted with trees which were growing in what appeared to be healthy soils, and then repeated with trees in the same orchard where the topsoil had been degraded (totally removed) by agricultural operations. The third phase repeated the trap crop trials only, but this time on three different study areas (all commercial farms) with the single cover crop which performed the best as a trap crop during phase two. Trials were modified from the first to the last phase to overcome practical implementation problems encountered along the way and to adapt to local conditions experienced in the commercial macadamia farming systems which served as research sites. Diversity of natural orchard vegetation was enhanced in phase three to improve conditions for natural predators as part of the trap crop treatments in the last phase and cover crops were finally first composted and then returned to the root zones of the macadamia trees as part of the soil quality enhancement treatments in the second phase. The results from the trap crop trials shows a significant effect of trap crops combined with increased orchard diversity in reducing unsound kernel percentages caused by stinkbug pests and demonstrate that trap crops combined with an increase in orchard diversity could be utilized in macadamia orchards as a more sustainable alternative to inorganic pesticides against the stinkbug complex. The most notable changes in the soil that took place with soil quality enhancement treatments were the significant increases in soil phosphorous content and pH which resulted not in an improvement in soil quality in terms of these two indicators but revealed an important issue about the use of compost containing animal manure originating from dairies or feedlots. In summary however, it was clear that although not all the soil quality indicators that were employed to assess changes in the soil with compost treatments improved significantly, a holistic consideration of all indicators portrays an overall improvement which was particularly significant in the degraded soil plots where the topsoil had been removed by prior agricultural activities.
NRF

MENVSC
Department of Ecology and Resource Management
The study investigated the impact of cover crops (Medicago sativa, Lotus corniculatus, Trifolium pratense, Melilotus alba and Phacelia tanacetifolia), bare soil and natural ground cover on pest and beneficial arthropods, soil health, crop yield, pest damage and weed suppression in avocado orchards. The trial plots were sited within established commercial avocado orchards with trees of similar cultivar (‘Hass’), soil-type and age, located in Levubu, Limpopo, South Africa. Mixtures of cover crops were planted in the alleys of avocado orchards and the effects were compared to that of a control (other half of the orchard). Mechanical clearing of vegetation in half of the alleys of different avocado orchards were compared to the other half that was left undisturbed. Data were collected during the flowering and fruit set stages of the avocado trees in the months of September - November 2019. Results revealed that there was higher abundance and diversity of flowering plants in the orchard alleys of the cover crop treatment compared to the control comprising of natural vegetation. Cover crops had a significantly positive effect on the soil health of the orchard but little or no effect on beneficial arthropods within the orchard nor any positive effect on the pests of avocados. However, the number of thrips scouted on the fruit were significantly less where cover crops were established. Avocado scale infection rates were also significantly lower where cover crops were established. There were significantly less arthropods, and specifically pests, pollinators and herbivores where the topsoil was removed mechanically. The yield resulting from the orchard half where cover crops were established were significantly higher. More research still needs to be done about the use, management and impact of cover cropping on not only commercial avocado orchards but on other fruit crops. This study shows good evidence for the benefits for using cover crops and the negative effects in having no vegetation cover in the orchards.
NRF