Esporulação in vivo, período de suscetibilidade dos tecidos e reação de tangerinas e híbridos a Alternaria alternata
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Data
2006-09-26
Autores
Reis, Renato Ferrari dos [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Este trabalho teve como objetivos determinar o efeito da idade da lesão de mancha marrom de Alternária (MMA) na produção conidial em folhas, ramos e frutos, a produção conidial sob diferentes condições de umidade relativa, a influência da aplicação de fungicidas na supressão da produção de conídios, o efeito da idade de maturação de folhas na suscetibilidade ao patógeno e a influência do tamanho de frutos na suscetibilidade à Alternaria alternata. A reação de espécies cítricas à MMA também foi avaliada. A esporulação em folhas teve início cerca de 10 dias depois do aparecimento de lesões de mancha marrom de Alternária, sendo que a maior produção de conídios ocorreu a partir de 20 dias, estendendo-se até 40 dias de idade. A produção de conídios foi superior em folhas do que em ramos ou frutos. A esporulação por unidade de área de lesão em folhas foi maior nos tangelos Minneola e Orlando , em relação ao tangor Murcott . A produção conidial em lesões de folhas foi mais abundante a partir de 85, 92,5, 96 e 100% de umidade relativa. A aplicação de fungicidas do grupo das estrobilurinas e dos cúpricos suprimiu a esporulação em lesões nas folhas por cerca de 14 a 21 dias após a aplicação. Folhas de tangelo Minneola apresentaram maior quantidade e maiores tamanhos de lesões até 20 dias de idade. O híbrido Nova foi o mais resistente entre os materiais genéticos estudados, sendo que folhas a partir de 16 dias de idade...
The objectives of this study were to evaluate: i) the effect of age of Alternaria brown spot (ABS) lesions on conidial production on leaves, twigs and fruit, ii) conidial production under different relative humidities, iii) influence of fungicide application on conidial production and iv) effect of leaf age on susceptibility to the disease and the influence of fruit size on the severity of brown spot. The reaction of the different citrus species to ABS was also studied. Sporulation on leaves began about 10 days after symptoms developed, was abundant from 20 to 40 days, and declined thereafter. Conidial production was far greater on leaf than fruit or twig lesions. Spore production per unit area of leaf lesion was greater on the more susceptible hybrids, Minneola and Orlando tangelos than on the less susceptible Murcott tangor. Conidial production on leaf lesions was more abundant at 85, 92.5, 96 and 100% relative humidity (RH) and almost nil at lower RH. Application of pyraclostrobin, trifloxyztrobin, azoxystrobin and copper fungicides suppressed the sporulation on leaf lesions for about 14 to 21 days after application. Minneola tangelo leaves had the greatest number and the largest lesions by 20 days or later. The Nova and Murcott hybrids were the most resistant of the cultivars and leaves showed few lesions when they were 16-days-old or older at inoculation. Leaves of Dancy tangerine were more susceptible than on leaves of Orlando tangelo and the Sunburst mandarin. For disease severity, there was a significant... (Complete abstract click electronic access below)
The objectives of this study were to evaluate: i) the effect of age of Alternaria brown spot (ABS) lesions on conidial production on leaves, twigs and fruit, ii) conidial production under different relative humidities, iii) influence of fungicide application on conidial production and iv) effect of leaf age on susceptibility to the disease and the influence of fruit size on the severity of brown spot. The reaction of the different citrus species to ABS was also studied. Sporulation on leaves began about 10 days after symptoms developed, was abundant from 20 to 40 days, and declined thereafter. Conidial production was far greater on leaf than fruit or twig lesions. Spore production per unit area of leaf lesion was greater on the more susceptible hybrids, Minneola and Orlando tangelos than on the less susceptible Murcott tangor. Conidial production on leaf lesions was more abundant at 85, 92.5, 96 and 100% relative humidity (RH) and almost nil at lower RH. Application of pyraclostrobin, trifloxyztrobin, azoxystrobin and copper fungicides suppressed the sporulation on leaf lesions for about 14 to 21 days after application. Minneola tangelo leaves had the greatest number and the largest lesions by 20 days or later. The Nova and Murcott hybrids were the most resistant of the cultivars and leaves showed few lesions when they were 16-days-old or older at inoculation. Leaves of Dancy tangerine were more susceptible than on leaves of Orlando tangelo and the Sunburst mandarin. For disease severity, there was a significant... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Cítricos, Fungicidas, Tangerina, Citrus reticulata, Fungicide
Como citar
REIS, Renato Ferrari dos. Esporulação in vivo, período de suscetibilidade dos tecidos e reação de tangerinas e híbridos a Alternaria alternata. 2006. xii, 81 f. Tese (doutorado) - Universidade Estadual Paulista, Faculdade de Ciências Agrárias e Veterinárias, 2006.