Optimization of the assessment of anthracnose severity in artificially inoculated common beans

Abstract

The aim was to estimate the minimum number of plants required per plot to assess the anthracnose severity by artificial inoculation of V2 stage plants. Seventy-eight carioca common bean cultivars were inoculated in 13 experiments to assess its reaction to races 65, 73, 81, and 89 of Colletotrichum lindemuthianum. Sample sizes ranged from one to nine plants were adopted to setting the number of plants per plot. A total of 1000 samplings were performed for each sample size. The following parameters were estimated in each sampling: accuracy, coefficient of variation and Pearson’s correlation. The mean values of each parameter in the 1000 samplings for each sample size were subjected to quadratic regression with a plateau as a function of sample size for each experiment. Six plants per plot were needed to assess the severity of anthracnose by artificially inoculating the pathogen on common bean plants at the V2 stage.