O amendoim é freqüentemente invadido por fungos toxigênicos antes da colheita. Este trabalho teve como objetivos: determinar a micoflora do solo, ar, sementes plantadas, flores, ginóforo e grãos e cascas de amendoim em diferentes fases de maturação e após a secagem; analisar aflatoxinas B1, B2, G1 e G2, ácido ciclopiazônico e fumonisinas B1 e B2 nas sementes plantadas, grãos e cascas de amendoim em diferentes fases de maturação e após a secagem. Os fungos mais freqüentes nos grãos e cascas de amendoim foram Fusarium spp. e Aspergillus flavus. A espécie A. flavus também foi encontrada em amostras do solo e do ar. Aflatoxinas e ácido ciclopiazônico foram detectados em 32 % das amostras de grãos de amendoim analisadas em concentrações que variaram de 4,20<font face=\"symbol\">mg/kg a 198,84 <font face=\"symbol\">mg/kg e de 260 <font face=\"symbol\">mg/kg a 600 <font face=\"symbol\">mg/kg, respectivamente. Nas cascas somente aflatoxinas foram detectadas em concentrações que variaram de 5,76 <font face=\"symbol\">mg/kg a 218,52 <font face=\"symbol\">mg/kg. Fumonisinas não foram detectadas. Boas práticas agrícolas são indicadas para região. / Peanuts are contaminated frequently by toxigenic fungi before harvest. the present study aimed to: identify the mycoflora of the soil, air, flower, pegs, peanut kernels and hulls in the different maturation stages and after drying; determinate the occurrence of aflatoxins B1, B2, G1 and G2, cyclopiazonic acid (CPA) and fumonisins B1 and B2 in peanut kernels and hulls in different maturation stages and after drying. Fusarium spp. Aspergullus flavus were the most frequent fungi isolated in peanuts hulls and kernels. A. flavus was isolated, also, in air and soil samples. Aflatoxins and cyclopiazonic acid were detected in 32% of the kernels samples in concentration from 4.20 <font face=\"symbol\">mg/kg to 198.84 <font face=\"symbol\">mg/kg and from 260 <font face=\"symbol\">mg/kg to 600 <font face=\"symbol\">mg/kg, respectively. In the peanut hulls only aflatoxins were detected in 24 % of the samples in concentration from 5.76 <font face=\"symbol\">mg/kg to 218.52 <font face=\"symbol\">mg/kg. Fumonisins were not detected. Good agriculture practices are indicated to region.

Resumo: O amendoim (Arachis hypogaea L.) é uma cultura em crescimento no Brasil, e a sua produção atual é de cerca de 300.000 toneladas/ano, numa área de plantio de mais de 115.200 hectares. Entretanto, a rentabilidade do produtor é limitada pela ocorrência de pragas e doenças, e o seu controle químico eleva o custo de produção. Entre as diversas pragas que atacam a cultura, as mais importantes no Brasil são o tripes (Enneothrips flavens Moulton, 1941 - Thysanoptera: Thripidae) e a lagarta do pescoço vermelho Stegasta bosquella (Chambers, 1875) - Lepidoptera: Gelechiidae). Não se conhecem variedades resistentes, mas o germoplasma do gênero Arachis, nativo da América do Sul, pode conter genes de resistência, ainda não explorados. Assim, este trabalho foi realizado visando avaliar o germoplasma silvestre disponível em coleção, e identificar possíveis fontes de resistência. Dois experimentos de campo foram conduzidos no município de Pindorama, SP. O primeiro envolveu quarenta e quatro acessos de espécies silvestres e dois anfidiploides híbridos de espécies silvestres, além de dois cultivares hypogaea conhecidos, usados como controles. As sementes foram inicialmente germinadas em casa de vegetação e, as plântulas transplantadas no campo. O delineamento experimental adotado foi o de blocos ao acaso com quatro repetições. Iniciando aos 30 dias após o plantio das mudas no campo, foram feitas amostragens de folíolos a cada 15 dias, num total de cinco avaliações. Anotaram-se: porcentagem de folíolos ainda fechados, com presença de tripes-do-prateamento e lagarta-do-pescoço-vermelho; notas dos sintomas de danos visuais de tripes e da lagarta, em folíolos recém abertos baseando-se numa escala de notas de 1 a 5. Outro experimento foi conduzido no campo, envolvendo 35 acessos de espécie silvestres, dois anfidiplóides e dois cultivares controles. O delineamento experimental... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The peanut (Arachis hypogaea L.) is a crop of increasing importance in Brazil, and its present production is around 300,000 tons/year, over a planting area of more than 115,200 hectares. However, peanut grower profitability is limited by the occurrence of pests and diseases, whose chemical control raises costs of production. Among the pests known to affect the peanut crop, the most important in Brazil are the tripes (Enneothrips flavens) and the redneck worm (Stegasta bosquella). Resistant varieties are not known, but the germplasm of Arachis, native of South America, may contain genes of resistance, yet not explored. And so, this work was done to evaluate wild peanut collected germplasm, so as to identify possible sources of resistance. Two field experiments were carried out at Pindorama - SP. The first involved forty four wild Arachis accessions, two hybrid anfidiploids, obtained from crossings between species, and two A. hypogaea known cultivars, as the controls. Seeds were initially germinated in greenhouse conditions and, then, transplanted to the field. The field experiment consisted of a complete ramdomized block design with four replications. Starting at 30 days after plantlets were transplanted, samplings of leaflets were done at 15 day intervals, comprising five evaluations along the plant cycle. The following data were obtained: percentage of closed leaflets that showed the presence of thrips and/or redneck worm; damage ratings of thrips and redneckworm from recently opened leaves, using a scale of 1 to 5. Another experiment was conducted, and this involved thirty five wild accessions, two anfidiploids and two control cultivars. The experimental design and the insect evaluations followed the same criteria of the previous experiment. In this case, the following data were additionally collected, from treated (sprayed for pest control) and untreated plots: number and length... (Complete abstract click electronic access below) / Orientador: Arlindo Leal Boiça Júnior / Coorientador: Ignácio José de Godoy / Coorientador: Marcos Doniseti Michelotto / Banca: Júlio Cesar Galli / Banca: Antonio Lúcio Mello Martins / Mestre

O objetivo do estudo foi avaliar a produção forrageira e o valor nutritivo do consórcio entre gramíneas do gênero Cynodon (Cv. Tifton 85 ou Coastcross) com Arachis pintoi (Amendoim forrageiro cv. Amarillo). O experimento foi conduzido na Unidade de Ensino e Pesquisa de Bovinocultura de Leite da Universidade Tecnológica Federal do Paraná, Câmpus Dois Vizinhos, Sudoeste do Paraná. Foi utilizada uma área de aproximadamente 3000 m2, distribuída em 12 piquetes de 15 x 15 m. O delineamento experimental foi de blocos ao acaso, com quatro tratamentos e três repetições. Os tratamentos foram: Tifton 85 e Coastcross em cultivo estreme, Tifton 85 + amendoim forrageiro e Coastcross + Amendoim forrageiro com implantação intercalada e sucessiva de uma linha para a gramínea e três linhas seguidas para a leguminosa. Foi avaliada a produção total, massa de forragem, componentes estruturais, material morto, outras espécie e massa de Amendoim forrageiro, no pré e pós pastejo de carga animal. Para os componentes nutricionais foram mensurados os percentuais de proteína bruta, fibra em detergente neutro e ácido, digestibilidade da matéria seca, matéria mineral e matéria seca das lâminas foliares, colmo+bainha, Amendoim forrageiro e da massa de forragem disponível da simulação de pastejo. O consórcio do Amendoim forrageiro com as gramíneas do gênero Cynodon reduziu a produção total de massa de forragem no piquete, suportando menor carga animal em pastejo. A produção de massa de forragem foi similar entre as cv. Tifton 85 e Coastcross, em cultivo singular. Apesar da redução da produção com a sua inserção, a produção do Amendoim forrageiro se manteve no decorrer das estações, indicando boa adaptação desta leguminosa no Sudoeste do Paraná. Os componentes estruturais dos cultivares avaliado apresentam valor nutritivo diferente. A cultivar Coastcross teve o menor teor de fibra, seja em cultivo solteiro ou no consórcio, enquanto a cultivar Tifton 85 tem maiores valores de MS. A inclusão do Amendoim forrageiro adicionou maiores teores de proteína quando consorciadas com pastagem de gramíneas em final de ciclo produtivo, além de reduzir o teor de FDN e FDA. A inclusão de Amendoim forrageiro no consórcio de gramíneas do gênero Cynodon interferiu na produção de massa e seus constituintes, bem como em seu valor nutricional. / This research aimed to evaluate the production and nutritive value of genus Cynodon (Cv. Tifton 85 or Coastcross) and the intercropping with Arachis pintoi (Amendoim forrageiro cv. Amarillo). The experiment was carried out at the Unidade de Ensino e Pesquisa de Bovinocultura de Leite da Universidade Tecnológica Federal do Paraná, Campus Dois Vizinhos, South-West of Parana, in a experimental area of approximately 3.000 m2, distributed in 12 paddock of 15 x 15 m. The experimental design was a randomized block design, with four treatments and three repetitions. The treatments were: Tifton 85 and Coastcross in single crop, Tifton 85 + forage peanut and Coastcross + forage peanut with rotated and successive implantation of one line to the grass and three consecutive lines to the legume. The total production, forage mass, structural compounds, dead material, other species and forage mass of peanut on pre and post grazing as well as the stocking rate were evaluated. For fodder nutritional components, were measure the content of crude protein, neutral and acid detergent fiber, digestibility of dry matter, mineral matter and dry matter of leaves, stem of grasses, forage peanut and total forage mass available of grazing simulation. The intercropping of forage peanut with the Cynodon genus fodder reduced total forage mass production at the the picket, supporting lower animal load on grazing. The forage mass production was the same between cv. Tifton 85 and Coastcross in pure crop. Despite the production decline when mixed with peanut forage, the production of legume is the same throughout all seasons, pointing a great adaptation in Southwest of Paraná. The lower fiber contents were found for treatments with Coastcross and higher dry matter contents is for cv. Tifton 85. The mixed with forage peanuts added higher levels of protein at the end of the productive cycle, besides reducing the fibrous contents. The inclusion of peanut forage mixed with Cynodon genus interferes on mass production and its constituents, and its nutritional value.

O objetivo do estudo foi avaliar a produção forrageira e o valor nutritivo do consórcio entre gramíneas do gênero Cynodon (Cv. Tifton 85 ou Coastcross) com Arachis pintoi (Amendoim forrageiro cv. Amarillo). O experimento foi conduzido na Unidade de Ensino e Pesquisa de Bovinocultura de Leite da Universidade Tecnológica Federal do Paraná, Câmpus Dois Vizinhos, Sudoeste do Paraná. Foi utilizada uma área de aproximadamente 3000 m2, distribuída em 12 piquetes de 15 x 15 m. O delineamento experimental foi de blocos ao acaso, com quatro tratamentos e três repetições. Os tratamentos foram: Tifton 85 e Coastcross em cultivo estreme, Tifton 85 + amendoim forrageiro e Coastcross + Amendoim forrageiro com implantação intercalada e sucessiva de uma linha para a gramínea e três linhas seguidas para a leguminosa. Foi avaliada a produção total, massa de forragem, componentes estruturais, material morto, outras espécie e massa de Amendoim forrageiro, no pré e pós pastejo de carga animal. Para os componentes nutricionais foram mensurados os percentuais de proteína bruta, fibra em detergente neutro e ácido, digestibilidade da matéria seca, matéria mineral e matéria seca das lâminas foliares, colmo+bainha, Amendoim forrageiro e da massa de forragem disponível da simulação de pastejo. O consórcio do Amendoim forrageiro com as gramíneas do gênero Cynodon reduziu a produção total de massa de forragem no piquete, suportando menor carga animal em pastejo. A produção de massa de forragem foi similar entre as cv. Tifton 85 e Coastcross, em cultivo singular. Apesar da redução da produção com a sua inserção, a produção do Amendoim forrageiro se manteve no decorrer das estações, indicando boa adaptação desta leguminosa no Sudoeste do Paraná. Os componentes estruturais dos cultivares avaliado apresentam valor nutritivo diferente. A cultivar Coastcross teve o menor teor de fibra, seja em cultivo solteiro ou no consórcio, enquanto a cultivar Tifton 85 tem maiores valores de MS. A inclusão do Amendoim forrageiro adicionou maiores teores de proteína quando consorciadas com pastagem de gramíneas em final de ciclo produtivo, além de reduzir o teor de FDN e FDA. A inclusão de Amendoim forrageiro no consórcio de gramíneas do gênero Cynodon interferiu na produção de massa e seus constituintes, bem como em seu valor nutricional. / This research aimed to evaluate the production and nutritive value of genus Cynodon (Cv. Tifton 85 or Coastcross) and the intercropping with Arachis pintoi (Amendoim forrageiro cv. Amarillo). The experiment was carried out at the Unidade de Ensino e Pesquisa de Bovinocultura de Leite da Universidade Tecnológica Federal do Paraná, Campus Dois Vizinhos, South-West of Parana, in a experimental area of approximately 3.000 m2, distributed in 12 paddock of 15 x 15 m. The experimental design was a randomized block design, with four treatments and three repetitions. The treatments were: Tifton 85 and Coastcross in single crop, Tifton 85 + forage peanut and Coastcross + forage peanut with rotated and successive implantation of one line to the grass and three consecutive lines to the legume. The total production, forage mass, structural compounds, dead material, other species and forage mass of peanut on pre and post grazing as well as the stocking rate were evaluated. For fodder nutritional components, were measure the content of crude protein, neutral and acid detergent fiber, digestibility of dry matter, mineral matter and dry matter of leaves, stem of grasses, forage peanut and total forage mass available of grazing simulation. The intercropping of forage peanut with the Cynodon genus fodder reduced total forage mass production at the the picket, supporting lower animal load on grazing. The forage mass production was the same between cv. Tifton 85 and Coastcross in pure crop. Despite the production decline when mixed with peanut forage, the production of legume is the same throughout all seasons, pointing a great adaptation in Southwest of Paraná. The lower fiber contents were found for treatments with Coastcross and higher dry matter contents is for cv. Tifton 85. The mixed with forage peanuts added higher levels of protein at the end of the productive cycle, besides reducing the fibrous contents. The inclusion of peanut forage mixed with Cynodon genus interferes on mass production and its constituents, and its nutritional value.

Desenvolvimento de metodologia para a determinação de aflatoxinas em amostras de amendoim usando espectrofluorimetria e análise dos fatores paralelos (PARAFAC). 2012. 92 f. Dissertação (Mestrado em Engenharia Química) - Instituto de Química, Universidade do Estado do Rio de Janeiro , Rio de Janeiro, 2012. Neste trabalho de pesquisa são descritos dois estudos de caso que se baseiam na determinação de aflatoxinas B1, B2, G1 e G2 em amostras de amendoim, utilizando a técnica de espectroscopia de fluorescência molecular. O primeiro estudo tem o objetivo de avaliar a metodologia empregada para a quantificação de aflatoxinas totais em amendoins, utilizando o método clássico de validação fazendo-se o uso da calibração univariada. Os principais parâmetros de desempenho foram avaliados visando certificar a possibilidade de implementação desta metodologia em laboratórios. O segundo estudo está focado na separação e quantificação destas aflatoxinas com a aplicação combinada da espectrofluorimetria e de um método quimiométrico de segunda ordem (PARAFAC) utilizando a calibração multivariada. Esta técnica pode ser empregada como uma alternativa viável para a determinação de aflatoxinas B1, B2, G1 e G2 isoladamente, tradicionalmente é feito por cromatografia líquida de alta eficiência com detector de fluorescência. Porém, como estes analitos apresentam uma larga faixa de sobreposição espectral e as aflatoxinas (B1 e G1) possuem intensidade de sinal de fluorescência bem abaixo das demais, a separação e quantificação das quatro aflatoxinas foi inviável. O estudo foi retomado com a utilização das aflatoxinas B2 e G2 e os resultados alcançados foram satisfatórios. O método utilizado para a quantificação de aflatoxinas totais apresentou bons resultados, mostrando-se como uma importante ferramenta para a determinação destes analitos. Alem disso, comtempla perfeitamente o que é requerido pela legislação brasileira para a análise de aflatoxinas B1, B2, G1 e G2, que tem como exigência em laudos finais de análise a declaração do somatório, em g/kg, destas aflatoxinas, ou seja, sem a necessidade de quantifica-las separadamente / This research describes two case studies that are based on the determination of aflatoxins B1, B2, G1 and G2 in peanut samples, using the technique of molecular fluorescence spectroscopy. The first study aims to evaluate the methodology used for the quantification of total aflatoxins in peanuts, using the classical validation method by employing univariate calibration. The main performance parameters were evaluated to assure the ability to ensure implementation of this methodology in laboratories. The second study focuses on the separation and quantification of these aflatoxins with the combined application spectrofluorimetry and a chemometric method of second order (PARAFAC) using the multivariate calibration. This technique can be used as a viable alternative for the determination of aflatoxins B1, B2, G1 and G2 alone, which traditionally is done by high performance liquid chromatography with fluorescence detection. However, as these analytes exhibit a wide range of spectral overlap and the aflatoxins (B1 and G1) have intensity of fluorescence signal well below the others, the separation and quantification of the four aflatoxins was not feasible. The study was resumed with the use of aflatoxins B2 and G2 and the results were satisfactory. The method used for quantification of total aflatoxins showed good results, showing itself as an important tool for the determination of these analytes. Furthermore, it contemplates exactly what is required by Brazilian legislation for the analysis of aflatoxins B1, B2, G1 and G2, which as a requirement in the final analysis reports is the statement of the sum, in g/kg, these aflatoxins, ie without the need to quantify them separately

Experiments were conducted at Blacksburg from 1975 to 1978 on soybean, Glycine max (L.) Merrill. The objectives were: (1) to study the inheritance of reaction to peanut mottle virus (PMV); (2) to determine the allelic relationships between genes for resistance from various germplasm sources; and (3) to screen a part of the soybean Plant Introduction germplasm collection and identify PMV-resistant strains. Soybean cultivars, Plant Introduction (PI) strains, and advanced generation progenies derived from selected crosses were artificially inoculated with PMV-S/V74S (a Virginia isolate) and evaluated for their reaction to PMV in the field and greenhouse. Two cultivars, 'Virginia' and 'Pine Dell Perfection', that were previously reported as resistant to a mild PMV strain were found to be susceptible to PMV-S/V74S. Crosses between resistant and susceptible lines and among resistant lines were made in the field in 1976 and 1977. The F₁, F₂, and F₃generation seedlings derived from selected crosses were tested for reaction to PMV in the greenhouse. It was shown that resistance in the cultivar 'Peking' is conditioned by a single recessive gene designated rpv₂. Evidence based on segregation in F₂ populations was also presented that indicates the presence of three other dominant genes for resistance to PMV-S/V74S. The three dominant genes are designated Rpv₁ (first reported by workers in Georgia), Rpv₃, and Rpv₄. Preliminary F₁ and F₂ data were obtained from crosses between 15 resistant PI strains and two resistant "testers," 'York' and PI 89,784. The F₂ data obtained from five crosses indicate the possibility of still other genes for resistance to PMV. The two susceptible lines used in the study, Virginia and PI 229,315, differed markedly in their reactions to PMV. The presence of different alleles or modifying genes controlling the susceptible reactions in the two lines is suggested. A total of 2161 FC and PI strains in Maturity Groups II, III, and IV were inoculated with PMV-S/V74S in the field during 1976 and 1977. Three hundred sixty-six strains that showed 10% or less virus infection were identified. These "resistant" strains provide a pool from which other genes for PMV resistance perhaps can be isolated. Differences in PMV disease reactions of plants from the same strain were noted when plants were tested in both the field and greenhouse. The differences were attributed to the following three factors: (1) differences in stage of plant growth at time of inoculation (field grown plants were generally larger at time of inoculation than plants inoculated in the greenhouse); (2) differences in environmental conditions between the field and greenhouse; and (3) the artist's airbrush inoculation technique was used in the field while the rub inoculation technique (mortar and pestle) was used in the greenhouse. / Ph. D.

The immigration, population dynamics and intra-field movement patterns of the tobacco thrips, Frankliniel/a fusca (Hinds), in peanuts were studied in 1990 and 1991 in the City of Suffolk, Virginia. The long-term goal was to improve our understanding of the role of tobacco thrips in the epidemiology of tomato spotted wilt virus in peanuts; the short-term goal was to develop quantitative descriptions of thrips development and movement for inclusion in a systems model intra-field movement patterns were assessed by establishing an isolated population of thrips in the center of a (67 m2) peanut field and monitoring the subsequent spread of thrips throughout the field. Thrips did not redistribute step-wise, as expected. Instead, thrips dispersed evenly throughout the field. However, failure to observe step-wise movement was probably due at least in part to the failure of insecticides to control the thrips in the corner areas of the experimental fields. Immigration and inter-field movement of adults were monitored with sticky traps. Thrips were caught on these traps only during the immigration period, which ended approximately two weeks after plant emergence. The spatial pattern of thrips immigration indicated that their movement was strongly influenced by wind direction and also by field borders. Proximity to fields planted the previous year in peanut also apparently influenced immigration. A computer model was developed based on previous and recent laboratory studies to simulate the phenology of the tobacco thrips as a function of temperature. The model was validated using field data from the 1991 season and used to help explain apparent anomalies in the 1990 data. The model confirmed that thrips damage to peanut was caused by two generations (F1 and F2) during June and July. Model results also suggested that rainfall was a significant mortality factor in thrips population dynamics. A second model was developed to simulate thrips movement in relation to wind speed and direction. This model will be used in future studies to test hypotheses about the ability of thrips to move within and between fields. / Master of Science

Peanuts are grown around the world and in United States where most peanuts are consumed after roasting. Peanuts are roasted to a specified color on L*a*b* scale as it is correlated with quality and acceptability. Two batches of Virginia type peanuts were acquired, one normal and other a high oleic variety. A surface response model using the Box-Behnken design was developed for Behmor 2000AB and GeneCafe coffee roasters, for normal and high oleic peanuts respectively with sample size, roast time and power/temperature as dependent variables and L* as a response variable. The model for Behmor was not significant (p>0.05 and R2 =0.87) but with effect contribution of roast time while the GeneCafe model was significant (p<0.05 and R2=0.98) with multiple first and second order effect contributions from temperature and roast time. Each model was validated and Behmor was found to be more consistent and predictable compared to GeneCafe. Both varieties of peanuts were roasted on each roaster and tested for volatile analysis using SPME GC/MS with high variation observed within samples which may be caused by uneven roasting. The volatile results showed similar trends for seventeen compounds between normal and high oleic samples. The Behmor roaster was more effective at predictable roasting for 50 to 100 g sample and more validation is needed on GeneCafe to improve its model. The results can help with quality testing of new varieties of Virginia type peanuts quickly without relying on large sample size typically used in other lab scale studies. / Master of Science in Life Sciences / Peanuts are grown around the world and in United States where most of it is consumed as a confection. They are roasted to a specified color on scale as it is correlated with quality and optimization. We wanted to develop a method of small-scale peanut roasting that allows peanut breeders to roast and evaluate quality of small samples of peanuts. We used an optimization method to test two different coffee roasters for peanut roasting (Behmor and GeneCafe roasters), with normal and high oleic peanuts. Behmor was more sensitive to changes in roast time while GeneCafe was more sensitive to temperature, roast time and combined effects. The models were validated on each machine and Behmor was found to be more consistent and predictable compared to GeneCafe. Peanuts were roasted on each roaster and tested for aroma compounds. The aroma compounds were similar between normal and high oleic samples. The Behmor roaster was more effective at predictable roasting of peanuts with sample size ranging from 50 to 100 g. Our results allow us to predictably roast very small lots of peanuts to support determination of flavor quality for peanut breeding research.

An advisory program to determine the timing of fungicide application for control of early leafspot of peanut, caused by Cercospora arachidicola, was developed based on growth responses of the pathogen to specific environmental conditions. The advisory program (89-ADV) assigned time-duration values to conditions conducive for infection (TDVi). Cumulative TDVi levels were used to determine when fungicide applications were needed. Various spray thresholds (TDVi=48, 72, 96, 120) of the 89-ADV program were compared to a 14-day spray schedule and an advisory program that was released to growers in 1981 (81-ADV). Leafspot incidence, area under the disease progress curve (AUDPC), spray number, yield and value were used to evaluate the performance of spray programs. Preliminary trials used Florigiant peanut and the fungicide chlorothalonil (1.26 kg/ha). The 89-ADV program with TDVi=48 performed exceptionally well for three consecutive years in field tests and in simulated disease environments reconstructed from historical weather data. Benefits of this program compared to the 81-ADV program included significant improvement of leafspot control, and improved crop yield and value. Based on performance, the 89-ADV program was delivered to growers as the on-line peanut leafspot advisory in 1989. Subsequent evaluations of the 89-ADV program included cultivars and fungicides in large multi-factorial experiments. Three classes of cultivars were identified: class I or highly susceptible, Florigiant and NC 9; class II or moderately susceptible, NC 7 and NC-V11; and class III or moderately resistant, NC 6. The efficiency of fungicide sprays was improved through effective leafspot control with about three fewer sprays per season than the 14-day spray schedule when chlorothalonil at 1.26 kg/ha, diniconazole at 140 g/ha or terbutrazole at 126 g/ha was applied on class I cultivars according to the TDVi=48 threshold of the 89-ADV program. The same efficiency was achieved when chlorothalonil or terbutrazole was applied on class II cultivars according to the TDVi=96. Cupric hydroxide at 1.79 kg/ha plus sulfur at 1.04 kg/ha or terbutrazole at 126 kg/ha with TDVi=96 as well as chlorothalonil at 1.26 kg/ha with TDVi=120 resulted in efficient control of disease on the class III cultivar. The spray adjuvant SoyOil 937® at 0.5% of spray volume consistently improved the performance of chlorothalonil, and allowed a reduction of application rate from 1.26 to 0.95 kg/ha without sacrificing disease control. The integrated use of cultivar resistance, fungicide, spray adjuvant, and TDVi thresholds of the 89-ADV program contributed to a reduction of fungicide input and improved disease control. / Ph. D.

Sclerotinia blight, caused by <i>Sclerotinia minor</i>, is a severe disease of peanut in Virginia. Vinclozolin (V), iprodione (I), dicloran (D), and pentachloronitrobenzene (PCNB) were evaluated for their fungitoxicity to <i>S. minor</i>. The mean ED₅₈ values for five isolates were found to be 0.07, 0.11, 0.91, and 1.27 μg/ml, for V, I, D, and PCNB, respectively, on fungicide-amended glucose yeast-extract agar (GYEA). Fungicide-resistant growth sectors developed on media amended with I or V. Nine such strains occurred; they were capable of growth on GYEA amended with up to 1000 μg/ml of I or V, and were cross-resistant to D or PCNB. Resistance was maintained in all but two strains after repeated culture in the absence of fungicide for 3 yr. In field microplots, two resistant strains were pathogenic to peanut and survived as well as a fungicide-sensitive field isolate. D, I and V were applied to peanuts in the microplots for 3 yr at total annual rates of 8.41, 3.36, and 2.52 kg/ha, respectively. Disease severity caused by the resistant strains was suppressed 19, 33, and 87% by D, I, and V, respectively, as compared to 15, 24, and 76% for the sensitive isolate. Isolates recovered from tissue biopsies still grew on fungicide-amended GYEA indicating that <i>in vitro</i> and <i>in vivo</i> resistance are not equivalent in this case. Fungicide treatments reduced sclerotial populations of all strains, and reduced the viability of sclerotia from sensitive but not resistant strains. Fungicide-resistant strains were capable of surviving and competing pathogenically in microplots infested with equal numbers of sclerotia from a sensitive and a resistant strain; this trend was enhanced by fungicide applications. A survey of 763 isolates from fields treated with these fungicides failed to detect resistant strains. One fungicide-resistant isolate was recovered from an iprodione-treated microplot originally infested with a sensitive field isolate. A technique utilizing excised peanut stems was devised to evaluate isolate pathogenicity, cultivar resistance to the disease, susceptibility of different age peanut tissues, and fungicide persistence on peanut stems in the field. The method was also used to screen fungicides; results verified previous findings which indicated that <i>in vitro</i> resistance is not equivalent to <i>in vivo</i> resistance. Resistance to these fungicides may eventually become a field problem, but with correct management they should provide years of disease control. / Ph. D. / incomplete_metadata