Dimensionamento de amostras para monitoramento do ácaro da leprose Brevipalpus phoenicis (Geijskes, 1939) em citros
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Data
2007-01-01
Autores
Lopes, Mariana Vilela
Oliveira, Carlos Amadeu Leite [UNESP]
Barreto, Modesto [UNESP]
Barbosa, José Carlos [UNESP]
Rossi, Fernanda Maria
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Fruticultura
Resumo
O controle do ácaro Brevipalpus phoenicis (Geijskes, 1939), transmissor do vírus da leprose, deve ser realizado quando sua população atinge o nível de ação, obtido pelo monitoramento de sua população, por meio de amostragens. Objetivou-se determinar o tamanho da amostra aceitável para estimar a população do ácaro, para posterior tomada de decisão. O experimento foi realizado na Fazenda Cambuhy, Matão - SP, no ano agrícola 2003-2004. Escolheu-se ao acaso um talhão da variedade Valência, com oito anos de idade, plantada no espaçamento 7x3,5m, com 2.480 plantas. Nesse talhão, foram inspecionados 1; 2; 3; 5; 10 e 100% das plantas, o que corresponde a 25; 50; 74; 124; 248 e 2.480 plantas, respectivamente, em caminhamento no sentido das linhas de plantio. Foram amostrados 3 frutos ou, na ausência destes, eram analisados ramos. de acordo com os resultados obtidos, observa-se que a porcentagem de erro na estimativa da média para a porcentagem de frutos com presença de ácaros, quando se amostra apenas 1% das plantas (25 plantas), é de 50%, ou seja, para uma infestação de 10%, a variação da porcentagem de frutos infestados estaria entre 5 e 15%, levando o produtor a subestimar ou a superestimar o nível de infestação, aumentando os gastos com pulverizações desnecessárias ou um controle ineficiente do ácaro. Para que o erro na amostragem fique dentro da situação aceitável, de 20 a 30% (em média 25%) de erro, deveriam ser amostradas 105 plantas. Na porcentagem de frutos com mais de 10 ácaros, verifica-se que, para a situação aceitável (20 a 30%), devem ser inspecionadas 540 plantas.
The control of the flat mite Brevipalpus phoenicis (Geijskes, 1939), vector of the citrus leprous virus, must be done when its population reach the threshold level, estimated by the monitoring the mite population density. The objective of this study was to determine the acceptable sample size for estimating the flat mite population, for later decision. The experiment was realized at the Cambuhy Farm, Matão - SP. It was casually select an orchard of Valência variety, eight years of age, planted in a spacing of 7 x 3.5m, with 2.480 plants. This orchard was inspected 1, 2, 3, 5, 10 and 100% of plants, respectively 25, 50, 74, 124, 248 and 2480 plants, by walking in the direction of the planting lines. It was inspected 3 fruits or branch per plant. According to the results, it was observed that the error percentage for estimating the mean percentage of fruits with flat mite, in actual situation of inspection of flat mite leprous in citrus, when it was inspected only 1% of plants (25 plants) the error is 50%, however, for an infestation of 10% the variation of infested fruits percentage was between 5 and 15%, leading the farmers to under or super estimate the mite population density, increasing the costs with unnecessary pulverization or an inefficient control of the flat mite. To the error in the sample remains in an acceptable situation (20 to 30% of error), 105 plants must be inspected. In fruits percentage with more than 10 flat mites, it was verified that for the acceptable situation (20 to 30%), 540 plants must be inspected.
The control of the flat mite Brevipalpus phoenicis (Geijskes, 1939), vector of the citrus leprous virus, must be done when its population reach the threshold level, estimated by the monitoring the mite population density. The objective of this study was to determine the acceptable sample size for estimating the flat mite population, for later decision. The experiment was realized at the Cambuhy Farm, Matão - SP. It was casually select an orchard of Valência variety, eight years of age, planted in a spacing of 7 x 3.5m, with 2.480 plants. This orchard was inspected 1, 2, 3, 5, 10 and 100% of plants, respectively 25, 50, 74, 124, 248 and 2480 plants, by walking in the direction of the planting lines. It was inspected 3 fruits or branch per plant. According to the results, it was observed that the error percentage for estimating the mean percentage of fruits with flat mite, in actual situation of inspection of flat mite leprous in citrus, when it was inspected only 1% of plants (25 plants) the error is 50%, however, for an infestation of 10% the variation of infested fruits percentage was between 5 and 15%, leading the farmers to under or super estimate the mite population density, increasing the costs with unnecessary pulverization or an inefficient control of the flat mite. To the error in the sample remains in an acceptable situation (20 to 30% of error), 105 plants must be inspected. In fruits percentage with more than 10 flat mites, it was verified that for the acceptable situation (20 to 30%), 540 plants must be inspected.
Descrição
Palavras-chave
sampling, flat mite, Citrus, Amostragem, Ácaro da leprose, Citros
Como citar
Revista Brasileira de Fruticultura. Sociedade Brasileira de Fruticultura, v. 29, n. 3, p. 671-676, 2007.