Desenvolvimento e validação de modelo de previsão para mancha preta dos citros em função de variáveis meteorológicas
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Data
2012-12-01
Autores
Ninin, Mariana Vilela Lopes
Spósito, Marcel Bellato
Scaloppi, Érika Auxiliadora Giacheto
Barbosa, José Carlos [UNESP]
Barreto, Modesto
Título da Revista
ISSN da Revista
Título de Volume
Editor
Grupo Paulista de Fitopatologia
Resumo
A mancha preta dos citros é uma doença causada pelo fungo Guignardia citricarpa que produz lesões em frutos em variedades de laranja doce comerciais, causando a queda precoce dos frutos, diminuindo a produtividade e levando a sua depreciação para o mercado de fruta fresca. O objetivo do trabalho foi desenvolver e validar um modelo de favorabilidade climática da mancha preta dos citros relacionado a ocorrência dos sintomas da doença no Estado de São Paulo. Desenvolveu-se um sistema empírico com base em um banco de dados da ocorrência da doença e das condições climáticas, em campo, nos municípios de Barretos/SP e Gavião Peixoto/SP, durante as Safras 2007/2008 e 2008/2009. A variedade de laranjeira doce utilizada nos experimentos foi a 'Valência' enxertada sobre limoeiro 'Cravo', com 10 anos de idade. Para a incidência da mancha preta foi avaliada a porcentagem de frutos com sintomas na planta e para a severidade, a porcentagem de casca lesionada por fruto. Na análise de regressão as variáveis climáticas e os dados de intensidade de doença de Barretos foram selecionados no procedimento 'stepwise'. As melhores equações de regressão foram selecionadas pelo coeficiente de determinação (R²) e pela significância da regressão no teste F (P < 0,05 e P < 0,01) que resultou na equação Y= -502,43 + 9,61 X10 + 4,78 X30 + 0,54 X46 - 7,9 X50 em que Y=Índice de Favorabilidade, X10 é a temperatura média, X30 é a umidade relativa média, X46 é o molhamento foliar e X50 é a temperatura média durante o molhamento foliar, determinados com dados de intervalos de sete dias. Procedeu-se a validação no campo no município de Gavião Peixoto durante a Safra 2008/2009, realizando a correlação entre a incidência e severidade observadas no experimento e os dados previstos que foram os determinados pela equação, sendo que a correlação mostrou-se positiva para a incidência da doença com um R²=0,87.
Citrus black spot is a disease caused by Guignardia citricarpa which produces lesions in fruits of commercial varieties of sweet orange, causing premature fall of fruits, decreasing the yield and leading to depreciation of the fresh fruit market. The aim of this study was to develop and validate a model of climate favorability for citrus black spot related to the occurrence of the disease symptoms in the state of São Paulo (SP). An empirical system was developed based on a data bank of the disease occurrence and the climate conditions in the field in the municipalities of Barretos/SP and Gavião Peixoto/SP, during the 2007/2008 and 2008/2009 crop cycles. The sweet orange variety used in the experiments was 'Valencia' grafted onto 'Rangpur' lime aged 10 years. For black spot incidence, the percentage of fruits with symptoms in the plant was evaluated, and for severity, the percentage of skin lesions per fruit was assessed. In the regression analysis, the climate variables and the data related to the disease intensity in Barretos were selected in the 'stepwise' procedure. The best regression equations were selected by the coefficient of determination (R²) and by the significance of regression in the F test (P <0.05 and P <0.01), which resulted in the equation Y = -502.43 + 9.61 X10 + 4.78 X30 + 0.54 X46 - 7.9 X50, where Y = Favorability Index, X10 is the average temperature, X30 is the average relative humidity, X46 is the leaf wetness and X50 is the average temperature during leaf wetness, determined with data from 7-day intervals. Validation was carried out in the field in Gavião Peixoto Municipality during the 2008/2009 crop cycle, correlating the incidence and severity observed in the experiment with the predicted data that were determined by the equation, and the correlation was positive for the disease incidence with R² = 0.87.
Citrus black spot is a disease caused by Guignardia citricarpa which produces lesions in fruits of commercial varieties of sweet orange, causing premature fall of fruits, decreasing the yield and leading to depreciation of the fresh fruit market. The aim of this study was to develop and validate a model of climate favorability for citrus black spot related to the occurrence of the disease symptoms in the state of São Paulo (SP). An empirical system was developed based on a data bank of the disease occurrence and the climate conditions in the field in the municipalities of Barretos/SP and Gavião Peixoto/SP, during the 2007/2008 and 2008/2009 crop cycles. The sweet orange variety used in the experiments was 'Valencia' grafted onto 'Rangpur' lime aged 10 years. For black spot incidence, the percentage of fruits with symptoms in the plant was evaluated, and for severity, the percentage of skin lesions per fruit was assessed. In the regression analysis, the climate variables and the data related to the disease intensity in Barretos were selected in the 'stepwise' procedure. The best regression equations were selected by the coefficient of determination (R²) and by the significance of regression in the F test (P <0.05 and P <0.01), which resulted in the equation Y = -502.43 + 9.61 X10 + 4.78 X30 + 0.54 X46 - 7.9 X50, where Y = Favorability Index, X10 is the average temperature, X30 is the average relative humidity, X46 is the leaf wetness and X50 is the average temperature during leaf wetness, determined with data from 7-day intervals. Validation was carried out in the field in Gavião Peixoto Municipality during the 2008/2009 crop cycle, correlating the incidence and severity observed in the experiment with the predicted data that were determined by the equation, and the correlation was positive for the disease incidence with R² = 0.87.
Descrição
Palavras-chave
Citros, Guignardia citricarpa, favorabilidade climática, Citrus, Guignardia citricarpa, Climate favorability
Como citar
Summa Phytopathologica. Grupo Paulista de Fitopatologia, v. 38, n. 4, p. 288-293, 2012.