Indução da expressão precoce de sintomas de Guignardia citricarpa em frutos de laranjeira 'pêra-rio'
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Data
2007-08-01
Autores
Baldassari, Ricardo Braga [UNESP]
Brandimarte, Ivan
Andrade, André Gustavo de [UNESP]
Souza, Danilo Cestari Gonçalves de [UNESP]
Moretto, Cristiane [UNESP]
Goes, Antonio de [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Fruticultura
Resumo
O presente trabalho teve por objetivo avaliar a influência de diferentes concentrações de ethephon na expressão precoce de sintomas de Guignardia citricarpa em frutos de laranjeira 'Pêra-Rio'. Para tal, frutos assintomáticos e isentos de aplicações com fungicidas, com 20 e 28 semanas após a queda de pétalas, foram coletados em área de comprovada existência da doença, no município de Conchal-SP e levados ao Laboratório de Fitopatologia da FCAV/UNESP, em Jaboticabal-SP, onde foram tratados com soluções nas seguintes doses de ethephon: i) 1,57 g L-1; ii) 2,10 g L-1; iii) 2,42 g L-1; iv) Testemunha (água). Todas acrescidas de imazalil a 0,25 g L-1, para prevenir podridões de pós-colheita. Após os tratamentos, os frutos foram mantidos em câmara incubadora para B.O.D., calibrada à temperatura de 25ºC ±1ºC, por 15 dias. Posteriormente, os frutos foram submetidos a quatro avaliações, em intervalos semanais, sendo atribuídas notas que variaram de zero (ausência de sintomas) a 6 (sintomas severos). Os dados da severidade da doença observados nos frutos colhidos prematuramente e submetidos aos diferentes tratamentos com ethephon foram comparados aos observados em frutos ensacados e não ensacados, mantidos no campo até a maturação natural. Constatou-se maior equivalência de sintomas nos frutos com idade entre 20 e 28 semanas, quando estes foram tratados com 2,10 g L-1 de ethephon e avaliados entre 28 e 35 dias. Concluiu-se que o emprego de ethephon, nestas condições, viabilizou a expressão precoce dos sintomas da mancha preta em frutos contendo infecções quiescentes de G. citricarpa, com antecedência de, pelo menos, 105 dias antes da colheita. Tal resultado constitui-se, portanto, em alternativa de grande aplicabilidade na detecção precoce de sintomas de mancha preta.
The aim of this study was to evaluate the influence of different ethephon rates in the precocity expression of symptoms of black spot caused by Guignardia citricarpa in fruits 'Pêra-Rio' sweet orange, in the orchard located in Conchal, SP. Asymptomatic fruits without fungicides applications and with 20 and 28 weeks after petal fall were collected and taken to the Laboratory of Plant Pathology of FCAV/UNESP, in Jaboticabal/SP, where they were treated with the following ethephon rates: i) 1.57 g L-1; ii) 2.10 g L-1; iii) 2.42 g L-1; iv) (water) (control). For all treatments, Imazalil at 0.25 g L-1 was added to prevent post harvest fungal disease. After the treatments, the fruit were kept in a chamber with a temperature of 25ºC ± 1ºC, during 15 days. Therefore, the fruits were evaluated four times with weekly interval using a scale from 0 (absence of symptoms) to 6 (severe symptoms). The data of disease severity observed in fruits colleted prematurely, under different ethephon rates were compared to those fruits bagged and unbagged remained in orchard until natural maturation. Major symptoms equivalence was verified in fruits with age 20 and 28 weeks, when they were treated with 2.10 g L-1 of ethephon, and evaluated between 28 and 35 days. It is concluded that the use of ethephon in this conditions may cause a precocious expression of symptoms of black spot in fruits with quiescent infections of G. citricarpa with 105 days before of harvest. These results are an alternative of great applicability to precocious detection of citrus black spot.
The aim of this study was to evaluate the influence of different ethephon rates in the precocity expression of symptoms of black spot caused by Guignardia citricarpa in fruits 'Pêra-Rio' sweet orange, in the orchard located in Conchal, SP. Asymptomatic fruits without fungicides applications and with 20 and 28 weeks after petal fall were collected and taken to the Laboratory of Plant Pathology of FCAV/UNESP, in Jaboticabal/SP, where they were treated with the following ethephon rates: i) 1.57 g L-1; ii) 2.10 g L-1; iii) 2.42 g L-1; iv) (water) (control). For all treatments, Imazalil at 0.25 g L-1 was added to prevent post harvest fungal disease. After the treatments, the fruit were kept in a chamber with a temperature of 25ºC ± 1ºC, during 15 days. Therefore, the fruits were evaluated four times with weekly interval using a scale from 0 (absence of symptoms) to 6 (severe symptoms). The data of disease severity observed in fruits colleted prematurely, under different ethephon rates were compared to those fruits bagged and unbagged remained in orchard until natural maturation. Major symptoms equivalence was verified in fruits with age 20 and 28 weeks, when they were treated with 2.10 g L-1 of ethephon, and evaluated between 28 and 35 days. It is concluded that the use of ethephon in this conditions may cause a precocious expression of symptoms of black spot in fruits with quiescent infections of G. citricarpa with 105 days before of harvest. These results are an alternative of great applicability to precocious detection of citrus black spot.
Descrição
Palavras-chave
Citrus sinensis, Phyllosticta citricarpa, ethephon, etileno, Citrus sinensis, Phyllosticta citricarpa, ethephon, Ethylene
Como citar
Revista Brasileira de Fruticultura. Sociedade Brasileira de Fruticultura, v. 29, n. 2, p. 269-275, 2007.