Dissertations / Theses on the topic 'Harvest diseases'

Experiments were performed at the Yuma Valley Agricultural Center to determine how timely harvest of cotton may affect aflatoxin contamination of cottonseed As the cotton was held in the field between the final irrigation and harvest, the quantity of aflataxin in the crop increased. Significant reductions in aflatoxin contents of seed were realized by harvesting in early September.

The overall goal of our study is to find effective and environmentally sound methods to reduce pre -harvest aflatoxin contamination of cottonseed in Arizona. The specific objectives are: 1) to screen a large number of bacteria for their ability to destroy the aflatoxin producing fungus, Aspeigillus flavus; 2) to test the efficacy and consistency of the recovered antagonistic bacterial isolates to reduce aflatoxin contamination of cottonseed in field trials; 3) to study the survival and competitiveness of the antagonists on cotton plants under prevailing field conditions; 4) to find innovative procedures to enhance survivability and competitiveness of the antagonists on cotton plants; and 5) to test the potential of the bacterial antagonists to reduce the population of A. flavus in field soils. Over 800 bacterial isolates, recovered from cotton field soils, cotton leaves, stems, and immature as well as opened bolls, were tested for ability to inhibit the growth of A. flavus on cottonseed. Six isolates partially or totally inhibited the fungus. All of these effective isolates prevented the fungus fioin infecting simulated pink bollworm exit holes in immature bolls in the field.

Thesis (PhD(Agric) (Horticulture))--University of Stellenbosch, 2005.
Bitter pit fruit in commercial consignments of apples still poses an economic threat to exporters from South Africa. Bitter pit develops pre-harvest, but gets progressively worse during storage and is only traceable once the lesions appear after storage. Accurate, early indications of bitter pit incidence will allow for remedial pre-harvest measures in the field, e.g. Ca foliar applications, to reduce the potential losses. Similarly, the automatic detection of a bitter pit fruit during packing will reduce financial losses by identifying unacceptable fruit before shipping. Fluorescence imaging is a fast, non-destructive technique, able to evaluate numerous fruits individually. Results of pre-harvest imaging on apples to identify fruit susceptible to bitter pit showed that pitted fruit were correctly classified, but misclassification of non-pitted fruit with fluorescence imaging was still too high. NIR-spectroscopy point meter readings could distinguish visible bitter pit lesions from healthy tissue. Important wavelengths associated with visible bitter pit were identified. This technique could also identify immature apples, more prone to bitter pit development. It could however not distinguish between bitter pit and non-pitted fruit when applied randomly on the calyx end of apples at harvest. Pre-harvest foliar applications to increase fruit Ca content and reduce bitter pit incidence, is a standard practice world wide. External Ca uptake by fruit was monitored to determine the efficacy of applications during different stages of fruit development. Two periods of efficient uptake of external Ca were identified, viz., cell division and the last few weeks before harvest. Foliar Ca applications from 40 days after full bloom were more effective in increasing fruit Ca content and reducing bitter pit incidence than at 80 days after full bloom, which was recommended previously. Mineral analysis of fruit has been used with variable success to predict bitter pit prior to harvest. The possibility of increasing the accuracy of existing predictive models by using analysis of individual fruit rather than pooled samples, was investigated. By improving the normality of different mineral distributions and decreasing the overlap between pitted and non-pitted fruit classes, it was attempted to improve the reliability of predictions based on variable threshold values. The Ca distribution showed a variation between pitted and nonpitted classes, but still a significant overlap between classes reduced the accuracy of the predictive capacity of this distribution. Even though our results produced a correct classification of 85% for non-pitted fruit, which can be useful, this was still below the required tolerance, of less that 2%, expected on the market. The effect of pruning and fruit bearing position on two-year-old wood on dry mass and Ca allocation of fruit was determined. ‘Golden Delicious’ fruit set was the lowest at the basal bearing position compared to the other positions evaluated and was contrary to expectations. Fruit in a terminal bearing position was superior to the basal position regarding total dry weight and fruit size. Distal wood possibly inhibited growth and set on the basal position via auxin distribution. Ca allocation differed between seasons and cultivars and could either be influenced by bearing position or presence or absence of re-growth.

Thesis (Ph. D.)--West Virginia University, 2000.
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Thesis (MEng) -- Stellenbosch University, 2014.
ENGLISH ABSTRACT: As overpopulation threatens the world’s ability to feed itself, food has become an invaluable resource. Unfortunately, almost a third of the food produced for human consumption is lost annually. Pests including insects, phytopathogens and weeds are responsible for more than a third of the annual major crop losses suffered around the world. The majority of current post-harvest control strategies employ synthetic agents. These compounds, however, have been found to be detrimental to the environment as well as human health, which has led researchers to investigate alternative strategies. Biocontrol agents are environmentally compatible, have a lower toxicity and are biodegradable, making them an attractive alternative to the synthetic control agents. The lipopeptides produced by Bacillus spp. in particular, have shown great potential as biocontrol agents against various post-harvest phytopathogens. Most biocontrol strategies apply the biocontrol organism, for example Bacillus, directly, whereas this study focused on the use of the lipopeptide itself as an antifungal agent. This is advantageous as the lipopeptides are less sensitive to their surroundings, such as temperature and pH, compared to living organisms, allowing for the production of a standardized product. This study investigated the production of the Bacillus lipopeptides surfactin, fengycin and iturin under controlled batch conditions. Parameters increasing lipopeptide production were quantified, focussing on antifungal lipopeptides (iturin and fengycin), and lipopeptide production was optimized. Experiments were performed in a fully instrumented 1.3 L bench-top bioreactor and lipopeptide analyses were performed via high pressure liquid chromatography (HPLC) and liquid chromatography-mass spectroscopy (LC-MS). After screening four Bacillus spp., Bacillus amyloliquefaciens DSM 23117 was found to be the best antifungal candidate. This was based on it outperforming other candidates in terms of maximum antifungals produced, Yp/x,antifungals (yield per cells), and antifungal productivity. Nitrate, in the form of NH4NO3, was critical for lipopeptide production and an optimum concentration was observed above which the CDW (cell dry weight) no longer increased significantly and both μmax (maximum specific growth rate, h-1) and lipopeptide production decreased. For μmax, the optimum NH3NO4 concentration was 10 g/L and for lipopeptides it was 8 g/L. At these respective NH4NO3 concentrations μmax = 0.58 (h-1), the maximum antifungals (fengycin and iturin) were 285.7 mAU*min and the maximum surfactin concentration was 302 mg/L. The lipopeptides produced by B. amyloliquefaciens, the antifungals (fengycin and iturin) and surfactin, are secondary metabolites, regardless of the optimization treatment, i.e. increased NH4NO3 concentrations. Using 30% enriched air extended the nitrate utilization period, suggesting that when increasing supply concentration, more oxygen was available to act as electron acceptors, allowing nitrate to be used for lipopeptide production. The number of iturin and fengycin homologues generally increased with an increase in nitrate concentration. This suggested that process conditions, such as nitrate concentration, can be used to manipulate homologue ratios, allowing for the possibility to tailor-make biocontrol-agent upstream, during the production process, and possibly increase the efficacy of the biocontrol strategy. The lipopeptides produced by B. amyloliquefaciens showed complete inhibition against Botryotinia fuckeliana and diminished the growth capabilities of Botrytis cinerea. No inhibition was observed against Penicillium digitatum. These results indicate potential of the biocontrol strategy, although scale-up and fed-batch studies are recommended, especially when considering commercial implementation. Studies regarding the lipopeptide application method, i.e. a single application or multiple applications, should also be investigated as this will influence the efficacy of the lipopeptides against the target organisms.
AFRIKKANSE OPSOMMING: Met oorbevolking wat die wêreld se vermoë om die groeiende bevolking te onderhou belemmer, het dit noodsaaklik geword om huidige voedselbronne te beskerm. Daar word beraam dat een derde van die voedsel wat wêreldwyd geproduseer word vir menslike verbruik verlore gaan elke jaar. Verder is insekte, plantpatogene en onkruide verantwoordelik vir meer as ‘n derde van die verliese rakend jaarlikse oeste. Meeste bestaande na-oes beheermetodes maak gebruik van sintetiese stowwe. Ongelukkig kan hierdie verbindings nadelig wees vir die omgewing sowel as menlike gesondheid. Navorsers het hulsef dus toespits daarop om alternatiewe beheermetodes te ondersoek. Bio-beheermetodes is omgewingsvriendelik sowel as bio-afbreekbaar, wat hulle ideale alternatiewe maak vir die sintetiese stowwe. Bacillus spp. lipopeptiede het veral hoë potensiaal getoon as bio-beheermiddels teen verskeie na-oes plantsiektes. Meeste bio-beheermetodes wend die biobeheer organisme, soos Bacillus, direk aan, waar hierdie studie op die gebruik van lipopeptiede as ‘n beheermiddel gefokus het. Die voordeel is dat lipopeptidiede minder sensitief is vir hul omgewings, soos temperatuur en pH, i.v.m. organismes en die moontlikheid bied van ‘n gestandardiseerde produk. Hierdie studie het die produksie van spesifieke Bacillus lipopeptide, naamlik surfactin, fengycin en iturin, onder beheerde lottoestande ondersoek. Parameters wat lipopeptied produksie verhoog is gekwantifiseer, spesifiek antifungiese middels (iturin en fengycin) en lipopeptied produksie is geoptimeer. Eksperimente is uitgevoer in ‘n 1.3 L bioreaktor en lipopeptiedanaliese is met behulp van hoë druk vloeistof chromatografie en vloeistofchromatografie-massa spektroskopie uitgevoer. Van die vier moontlike Bacillus spp., was Bacillus amyloliquefaciens DSM 23117 die mees belowende antifungus-produserende kandidaat. Dit het beter resultate gelewer in terme van maksimale antifungiese produksie, Yp/x,antifungies (opbrengs per sel) asook antifungiese produktiwiteit. Nitraat, in hierdie geval NH4NO3, was noodsaaklik vir lipopeptied produksie en ‘n optimale konsentrasie is waargeneem waarbo die seldigtheid nie meer beduidend toegeneem het nie en beide die μmax (maksimale spesifieke groei tempo, h-1) en lipopeptied produksie afgeneem het. Die optimale NH4NO3 konsentrasie vir μmax was 10 g/L en vir lipopeptiedproduksie was 8 g/L. By 10 g/L NH4NO3 was μmax = 0.58 (h-1) en by 8 g/L was die maksimale antifungiese produksie (fengycin en iturin) 285.7 mAU*min en die maksimale surfactin produksie 302 mg/L onderskeidelik. Die lipopeptide, die antifungiese middels (fengycin en iturin) en surfactin, geproduseer deur B. amyloliquefaciens is sekondêre metaboliete, ongeag van die optimerings-behandelinge wat toegepas word, soos ‘n verhoging in NH4NO3 konsentrasie. Die gebruik van 30% verrykte suurstof het die nitraat verbruikingsperiode verleng, wat voorgestel het dat met die verryking, meer suurstof beskikbaar was om te dien as finale elektron ontvanger en sodoende die nitraat beskikbaar te stel vir lipopeptied produksie. Iturin en fengycin homoloë, oor die algemeen, het toegeneem soos wat die nitraat konsentrasie verhoog is. Hierdie resultate dui daarop dat prosestoestande, soos nitraat konsentrasie, gebruik kan word om die verhouding waarin lipopeptied homoloë geproduseer word te manipuleer. Hierdie resultate dui op die potensiaal vir die stroomop produksie van ‘n unieke bio-beheermiddel, wat die effektiwiteit van die bio-beheermetode moontlik sal verhoog. Die geproduseerde lipopeptiede het totale inhibisie getoon teen Botryotinia fuckeliana en ook fungiese aktiwiteit belemmer met Botrytis cinerea. Geen inhibisie is getoon teen Penicillium digitatum nie. Hierdie resultate toon die potensiaal van die bio-beheermetode, maar ‘n opskalerings-studie asook ‘n voerlot studie word aanbeveel, veral met die oog op moontlike kommersiële implementering van die strategie. Verdere studies met betrekking tot die aanwendingsmetode van die lipopeptiede moet ook verder ondersoek word, m.a.w. enkel teenoor menigte aanwendigs, aangesien dit die effektiwiteit van die lipopeptiede teen die teikenorganismes sal beïnvloed.

3 pp.
“Summer slump” is a decline in growth of alfalfa usually beginning in July in areas where maximum daily temperature exceeds 100 °F, such as the low elevation deserts of Southwestern U.S (Fig. 1). In more temperate regions, there is a gradual decrease in alfalfa yield in successive harvests throughout the year, but the yield decline in the summer is not as sharp as in hot summer regions. The term summer slump has also been applied to reduction in growth of perennial cool season grasses such as tall fescue during the summer.

Orientador: Benedito Carlos Benedetti
Texto em português e Inglês
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola
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Resumo: Botrytis cinerea Pers, causador da doença conhecida como mofo cinzento, é o principal problema para a conservação pós-colheita de uvas de mesa. A utilização do dióxido de enxofre (SO2) é a prática pós-colheita mais comum para o controle desta doença. Pesquisas buscam alternativas a este produto devido às reações que causa em pessoas alérgicas, danos que pode causar nos frutos e às restrições ao seu uso em sistemas de produção orgânico. Foram avaliados os efeitos da aplicação de uma atmosfera de 40% de CO2 por 24 ou 48 horas (pré-armazenagem) combinado com armazenagem em atmosfera controlada (AC) (12% O2 + 12% CO2) no controle de B. cinerea, e nos atributos de qualidade de uvas 'Flame Seedless' e 'Crimson Seedless'. Também foram avaliados, em uvas 'Crimson Seedless', e os efeitos da associação deste tratamentos com aplicações pré-colheita de cloreto de cálcio (CaCl2) ou dióxido de cloro (ClO2). Os tratamentos foram aplicados em uvas orgânicas infectadas de três formas: infectadas naturalmente, superficialmente inoculadas com conídios e inoculadas com uma baga coberta de micélio. Uvas 'Flame Seedless', naturalmente infectadas, tratadas com 40% de CO2 por 48 horas + AC apresentaram redução da podridão pós-colheita, de 22% para 0,6%, após 4 semanas, e de 100% para 7,4%, após 7 semanas. O pré-armazenamento em 40% de CO2 sozinho também limitou a incidência de mofo cinzento em frutos infectados naturalmente e em uvas inoculadas artificialmente, porém foi menos eficaz do que quando seguido pelo armazenamento em AC. A aplicação de CaCl2 ou ClO2 em pré-colheita reduziu a incidência do mofo cinzento em uvas 'Crimson Seedless' inoculadas com uma solução de conídios, porém não houve controle quando os cachos de uva foram inoculados com micélio. A aplicação de CaCl2 e ClO2 reduziram o mofo cinzento de 45% para 23,2% e 15.6%, respectivamente, em cachos inoculados com conídios e avaliados após 6 semanas armazenadas 0oC. O pré-tratamento com 40% CO2 + CA não afetou as características físico-químicas e sensoriais de uvas 'Crimson Seedless' ou 'Flame Seedless'. Em experimentos in vitro os tratamentos com 40% CO2 por 24 ou 48 h limitaram o crescimento micelial até 72 horas após o tratamento. A germinação dos conídios de B. cinerea foi retardada por 12h. Os resultados mostram que o pré-tratamento com 40% CO2 + CA possui grande potencial para ser adotado como prática comercial para conservação de uvas orgânicas
Abstract: Gray mold, caused by Botrytis cinerea Pers, is the main postharvest decay of table grapes. The use of sulfur dioxide (SO2) is the common post-harvest practice for its control. Several researchers are looking for alternative methods of control, because SO2 can cause allergic reactions, damage fruits and also it cannot be applied in organic production system. In this thesis, it was evaluated the effects of applying an atmosphere of 40% CO2 for 24 or 48 hours (pre-storage) combined with controlled atmosphere storage (CA = 12% O2 + 12% CO2) in the control of B. cinerea, and the effects in the quality and sensory attributes of 'Flame Seedless' and 'Crimson Seedless' table grapes. In addition, it was evaluated the efficacy of CaCl2 or ClO2 application in pre-harvest alone or in combination with pre-storage of 40% CO2 for 24 h + CA, to control gray mold on 'Crimson Seedless' table grapes, and the determination of the impact of these treatments on fruit quality. The treatments were applied in certified organic table grapes naturally infected, surface inoculated and nesting inoculated (inoculated with an infected berry). After 4 weeks of storage, the pre-storage in 40% CO2 for 48 hours + CA reduced postharvest rot from 22% to 0.6%, and after 7 weeks, the decay was reduced from 100% to 7.4% in 'Flame Seedless' naturally infected. The pre-storage in 40% CO2 alone also reduced the incidence of gray mold in fruits naturally infected and in artificially inoculated, but it was less effective than combined treatment. The application of CaCl2 or ClO2 pre-harvest reduced the incidence of gray mold on grapes 'Crimson Seedless' inoculated with a spore solution, but there was no control when fruits were nesting inoculated. After 6 weeks at 0oC, the application of CaCl2, and the ClO2 in fruits surface inoculated, reduced the gray mold from 45% to 23.2% and 15.6%, respectively. The pretreatment with 40% CO2 + CA did not affect quality and nor sensory attributes for both varieties tested. In vitro experiments, the treatment with 40% CO2 for 24 or 48 h limited mycelial growth for at least 72 hours after treatment. Conidial germination of B. cinerea was delayed for 12 hours. Our results showed the potential that pre-treatment with 40% CO2 associated with CA has to be adopted in commercial practice for preservation of organic grapes
Doutorado
Tecnologia Pós-Colheita
Doutor em Engenharia Agrícola

A queixada (Tayassu pecari) é um ungulado de grande importância tanto no sentido ecológico pelo seu rol vital na estruturação e composição das comunidades vegetais e para a conservação de ecossistemas bem como no sentido sócio-econômico, por ser fonte de alimento e renda para os caçadores de subsistência na Amazônia Peruana. Não obstante varias pesquisas relataram seu declínio em decorrência de sobre extração e citando a presença de epidemias como um problema potencial. Com o objetivo de avaliar a presença de doenças em populações de queixadas de vida livre e caracterizar os padrões de caça nesta espécie foi desenvolvido o presente estudo durante os anos 2008 e 2009 na Região de Madre de Dios. Foram coletados 103 soros provenientes de animais abatidos para caça de subsistência de duas comunidades indígenas e de animais capturados no interior de três áreas naturais protegidas. Os resultados evidenciaram a presença de anticorpos às doenças de brucelose, leptospirose, toxoplasmose, existindo diferencia na prevalência entre os locais de coleta. Esta corresponde à primeira avaliação sanitária de queixadas na Amazônia Peruana. Como parte complementar foram monitoradas as atividades de caça dos caçadores de subsistência das duas comunidades para caracterizar a área de caça utilizada, a produtividade, a pressão de caça e avaliar se a extração era sustentável. A caça das queixadas aparenta ser sustentável e a população caçada esta sendo adequadamente extraída em termos de sustentabilidade em longo prazo.
The peccary (Tayassu pecari) holds an important place in the Amazonian ecosystem. As seed dispersers they have measurable effects on their habitat, partly guiding structure and composition of the vegetation community. Additionally, their socio-economic role is unsurpassed as one of the most important sources of bushmeat for subsistence hunters in the Peruvian Amazon. Various studies have alarmingly reported the decline of several populations, possibly a result of overextraction due to hunting. However, passing reference was also made to disease and its possible role in population fluctuations. The following study, taking place in Madre de Dios during 2008 and 2009, evaluates the presence of disease in three wild peccary populations. It is the first of its kind in the Peruvian Amazon. A complimentary study characterizing human hunting patterns of peccaries in two indigenous communities is also reported. Exactly 103 serum samples from hunted or live-captured animals were obtained for the study. The results indicate the presence of antibodies to brucelose, leptospirose, and toxoplasmose, in wild populations, the distribution of which is not equal among the three sites. The complimentary study characterizes human hunting patterns of peccaries, focusing on the delimitation of hunting grounds and the quantification of hunting pressure, annual animal productivity, and sustainability of hunting activities. Hunting pressure was found to be well within the limits of sustainability.

INTRODUÇÃO: O Estado de São Paulo é o maior produtor de cana-de-açúcar dentre os demais estados da federação, alcançando uma área de 5.768.184 hectares (ha) cultivada no ano de 2013. Diversos estudos desenvolvidos recentemente no Brasil apontam para os impactos negativos à saúde humana no processo de colheita por meio da queima da cana-de-açúcar. Em 2007, foi assinado o Protocolo de Cooperação (Protocolo do Etanol Verde) entre o setor sucroalcooleiro e o governo estadual visando à antecipação das metas de redução de queima de cana-de-açúcar por meio do processo de mecanização da colheita. Diante deste cenário, faz-se necessária uma análise sobre os impactos à saúde humana neste período de implantação de práticas sustentáveis. OBJETIVO: Este trabalho tem como objetivo avaliar o impacto da produção canavieira, após a assinatura do Protocolo Etanol Verde (2007), em alguns municípios do noroeste paulista por meio da análise das evoluções dos métodos de colheita da cana-de-açúcar possíveis associações com as doenças do aparelho respiratório. METODOLOGIA: . A área de estudo foi definida por meio de técnicas de análise espacial utilizando o software ARCGIS 10.1 com criação de shapefile de incidência de internações por doenças do aparelho respiratório por município e calculado o Índice Local de Moran, possibilitando a identificação dos municípios com maiores incidências e que formam aglomerados espaciais (clusters). Foram consolidados dados secundários de internações por doenças respiratórias em todos os municípios do Estado de São Paulo entre os anos de 2008 e 2012, levando em consideração o mês mais seco do ano (julho) para composição da incidência. Concomitantemente, os aspectos socioeconômicos e físicos relevantes foram caracterizados na área de estudo. Em seguida, foi realizada a análise espacial da distribuição dos métodos de colheita de cana-de-açúcar nos 25 municípios selecionados e foram definidas variáveis de risco associadas à distribuição espacial da colheita e que potencializam o impacto na saúde respiratória da população, levando-se em consideração o decreto 47.700, SMA - SAA 004/08 e outras referências. A partir dos dados levantados, correlações foram calculadas entre as variáveis,(Regressões lineares e correlação de Pearson, pINTRODUCTION: The State of São Paulo is the largest producer of sugarcane among the other states of the country, reaching an area of 5,768,184 hectares (ha) planted in 2013 Several recent studies developed in Brazil point to. negative impacts on human health in the process of picking through the burning of cane sugar impacts. In 2007, the Protocol of Cooperation (Green Ethanol Protocol) was signed between the sugar and alcohol sector and the state government seeking to advance the goals of reducing the burning of cane sugar by the process of mechanical harvesting. Given this scenario, it is necessary to analyze the impacts to human health in this period of implementation of sustainable practices. OBJECTIVE: This study aims to evaluate the impact of sugarcane production, after signing the Protocol Ethanol Green (2007), in some municipalities in the northwest region by analyzing the evolution of methods of harvesting cane sugar, on diseases the respiratory system. METHODOLOGY:. The study area was defined by spatial analysis using ArcGIS 10.1 software to create shapefile incidence of hospitalizations for respiratory diseases by county and calculated the Local Moran Index, allowing the identification of municipalities with higher incidences and forming spatial clusters (clusters). Secondary data on admissions for respiratory diseases were consolidated in all counties of the State of São Paulo between 2008 and 2012, taking into account the driest month of the year (July) for composition of incidence. Concomitantly, the relevant socioeconomic and physical aspects were characterized in the study area. Then, the spatial distribution analysis of methods of harvesting sugar cane in 25 selected municipalities was performed and risk variables associated with the spatial distribution of harvest were defined and potentiate the impact on the respiratory health of the population, taking into consideration the decree 47.700, SMA - SAA - 004/08 and other references. From the data collected, correlations were calculated between the variables (linear regressions and Pearson\'s correlation, p