Padrão espacial e tamanho da amostra para avaliação da severidade da sigatoka-amerela da bananeira

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Yellow Sigatoka disease or leaf spot Banana caused by fungus Mycosphaerella musicola (anamorph Pseudocercospora musae), it is an important disease of banana disseminated throughout in Brazilian territory. This work aimed to determine the spatial pattern of the Sigatoka disease in the field and appropriate samples size for quantification of the disease in different planting areas and severity levels. The spatial pattern of the disease was investigated in three areas of bananas planting, being delimited in each planting a portion of thirty contiguous lines, with 30 covas/line. Yellow Sigatoka disease was evaluated in each plant-mother and, considering the respective location, the analysis of space spatials autocorrelation was made. The three areas presented aggregate pattern of diseased plants, with predominance of the three areas presented pattern of diseased plants, with predominance of the aggregation inside of the lines aggregation inside of the lines. To determinate the appropriate sizes of the samples, it was made pilots sampling in 30 plantings, being established in each planting a sub-area of 2 ha, where 50 plants were selected by systematic sampling and evaluated by diseaseseverity. The severity of the Sigatoka yellow in the 30 plantingareas submitted to pilots sampling varied from 5,3% to 46,7%, not being verified significant correlations between the severity levels and the plantings age, as well as of these last ones with the sizes of the samples. The samples size for quantification of Sigatoka yellow bananas severity were determinated considering the aggregate pattern of diseased plants. Obtained data were analyzed by method that specifies the acceptable mistake, with a aggregate pattern of diseased plants. The samples size were correlated negatively with the levels of disease severity (r = -0,60). Considering the planting area average, in futures studies of the severity of the Sigatoka yellow, at which excellent precision level is demanded (error = 5%), the sampling of 66 plants is recommended for each 2 ha cultivated, with the evaluation of the nine leaves more young/plant. The results obtained in this study serve as base for futures epidemic studies of the Sigatoka yellow banana, as data were originated from fields under different conditions and estimated considering growing needs of precision.

ASSUNTO(S)

fitopatologia banana epidemiologia sigatoka-amarela sampling amostragem phytopathometry epidemiology pseudocercospora musae fitopatomia mycosphaerella musicola musa spp

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