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

Abstract

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 sample’s 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 banana’s 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 spatial’s 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 pilot’s 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 disease’severity. The severity of the Sigatoka yellow in the 30 plantingareas submitted to pilot’s 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 banana’s 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 sample’s 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.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 sample’s 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 banana’s 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 spatial’s 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 pilot’s 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 disease’severity. The severity of the Sigatoka yellow in the 30 plantingareas submitted to pilot’s 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 banana’s 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 sample’s 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.