Determinação do efeito curativo de infecções de Guignardia citricarpa em frutos cítricos mediante o emprego de fungicidas sistêmicos e mesostêmicos
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Data
2006-03-17
Autores
Scaloppi, Eliana Mayra Torrecillas [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Embora o Brasil seja o maior produtor de laranja a nível mundial, a produção citrícola ressente-se de vários problemas de natureza fitossanitária, entre estes a mancha preta dos frutos cítricos, causada por Guignardia citricarpa. Esse fungo além de depreciar comercialmente os frutos, pode levar à queda precoce de mais de 80% da produção. O controle baseia-se no uso de fungicidas, sendo importante determinar o período curativo em que estes produtos estão sendo mais eficientes. Neste trabalho foi determinado o período curativo do pyraclostrobim e do carbendazim, em duas etapas fisiológicas do desenvolvimento dos frutos, sendo a primeira na fase de de queda de pétalas até a 8a semana, e a segunda repetindo-se o tratamento, porém a partir da 9a semana após a queda das pétalas. Para tal, procedeu-se o tratamento dos frutos com os fungicidas, os quais foram aplicados sob a forma de imersão, durante 1 minuto, sendo posteriormente ensacados com sacos de papel cristal, e mantidos assim até a 42a semana. Na primeira etapa, os níveis de incidência e severidade nos frutos tratados com fungicidas foram baixos até a 4a semana de exposição às infecções naturais, não diferindo estatisticamente entre si. Na segunda etapa, constatou-se maior eficiência do fungicida carbendazim, a qual se estendeu até a 6a semana de exposição. O pyraclostrobin, embora tenha se mostrado eficiente no controle da doença, manteve sua efetividade de forma mais consistente nas duas primeiras semanas de exposição. Admite-se que os fungicidas testados apresentaram excelente efeito curativo, resultados esses coerentes às respostas que têm sido observadas sob condições naturais de infecção.
Although Brazil is the largest world-wide orange producer, its production presents several disease problems, among these is the Citrus Black Spot (CBS) caused by Guignardia citricarpa. This fungs besides depreciating the fruits commercially can cause premature fall of more than 80% of the production. The control is based on the use of fungicides, being important to determine the healing period, in wich these products are more efficient. In the present work the healing period of pyraclostrobin and carbendazim was determined on two physiological stages of the fruits development, being the first in the petals fall stage until the 8th week and the second repeating the treatment, however starting from the 9th week after the petals fall. The fruits were treated with the fungicides, wich were applied on immersion form, during 1 minute, being after sacked with crystal paper bags and maintained like this until the 42nd weekend. In the first stage, the incidence levels and severity on the treated fruits were low until the 4th week of exposure to natural infections, presenting no statistic differences between then. In the second stage, the efficiency of carbendazim was larger, wich extended for 6 weeks of exposure. The pyraclostrobin, although has shown efficient in the disease control, maintained its effectiveness in a consistent form on the first two weeks. It is admitted that the tested fungicides presented excellent healing effect, corresponding to the results observed under natural conditions of infection.
Although Brazil is the largest world-wide orange producer, its production presents several disease problems, among these is the Citrus Black Spot (CBS) caused by Guignardia citricarpa. This fungs besides depreciating the fruits commercially can cause premature fall of more than 80% of the production. The control is based on the use of fungicides, being important to determine the healing period, in wich these products are more efficient. In the present work the healing period of pyraclostrobin and carbendazim was determined on two physiological stages of the fruits development, being the first in the petals fall stage until the 8th week and the second repeating the treatment, however starting from the 9th week after the petals fall. The fruits were treated with the fungicides, wich were applied on immersion form, during 1 minute, being after sacked with crystal paper bags and maintained like this until the 42nd weekend. In the first stage, the incidence levels and severity on the treated fruits were low until the 4th week of exposure to natural infections, presenting no statistic differences between then. In the second stage, the efficiency of carbendazim was larger, wich extended for 6 weeks of exposure. The pyraclostrobin, although has shown efficient in the disease control, maintained its effectiveness in a consistent form on the first two weeks. It is admitted that the tested fungicides presented excellent healing effect, corresponding to the results observed under natural conditions of infection.
Descrição
Palavras-chave
Frutas citricas - Doenças e pragas, Fungicidas, Controle químico, Citrus sinensis, Chemical control, Phyllosticta citricarpa
Como citar
SCALOPPI, Eliana Mayra Torrecillas. Determinação do efeito curativo de infecções de Guignardia citricarpa em frutos cítricos mediante o emprego de fungicidas sistêmicos e mesostêmicos. 2006. vii, 88 f. Dissertação (mestrado) - Universidade Estadual Paulista, Faculdade de Ciências Agrárias e Veterinárias, 2006.