SPATIAL-DISPERSION AND BINOMIAL SEQUENTIAL SAMPLING PLAN FOR CERCOSPORA-CAROTAE ON CARROTS

The spatial dispersion of lesions of Cercospora carotae on carrot leaves was described with Taylor's Power Law. Lesions had an aggregated pattern in carrot fields. The proportion of infected leaves could be estimated from the mean number of lesions per leaf. Binomial sequential sampling plans are presented for early and late carrots grown on muck soil in Quebec. A disease incidence action threshold of 80% infected intermediate leaves was used for early carrots, harvested from early to late August, and an action threshold of 50% infected intermediate leaves was used for late carrots, harvested from September to the end of the season. These sampling plans require a maximum sample size of 19 intermediate leaves and 30 intermediate leaves for early and late carrots, respectively. © 1990 Taylor & Francis Group, LLC.