Lettuce and Chinese cabbage may present yield reduction due to the occurrence of soft rot caused by Pectobacterium carotovorum subsp. carotovorum. This study aimed to determine the ideal sample size for assessing disease incidence in field surveys. Samples of soft rot incidence were conducted in eight lettuce growing areas and five Chinese cabbage growing areas, located in the main production cities around Pernambuco State. Considering 20% of acceptable error, the results pointed out that future surveys of the soft rot incidence on lettuce should analyze 32 plots with 4.5 m²/ha and 20 plants/plot, while for Chinese cabbage the sample should include 32 plots with 10.5 m²/ha and 20 plants/plot. No significant correlation (P=0.05) was found between disease incidence levels and sample sizes for both crops.
Pectobacterium carotovorum subsp. carotovorum; Lactuca sativa L.; Brassica pekinensis L.; sampling; pathometry
