Weibull distribution of lesion size in the stagonospora leaf spot of orchardgrass

Sherwood, R. T. 1987. Weibull distribution of lesion size in the Stagonospora leaf spot of orchardgrass. Phytopathology 77:715-717. Five resistant and five susceptible genotypes of Dactylis glomerata were could be rejected in favor of the Weibull distribution in all samples at a = inoculated with Stagonospora arenaria in two replicated greenhouse tests. 0.01. All samples showed a good fit to the Weibull distribution with Distributions of lesion length and area were determined for populations of location (a) set at minimum spot size. Weibull maximum likelihood lesions on single leaves, using samples of 50 lesions per leaf. The two trials estimates for shape (ý) were significantly lower than c expected for a gave closely similar results. The null hypothesis that size was normally normal distribution; this further demonstrated positive skewness. Values distributed could be rejected for resistant genotypes but not for suceptible, for a, c, and slope (b) were significantly lower for resistant genotypes than using the Shapiro-Wilk w statistic at P = 0.01. The sample of all genotypes for susceptible genotypes. Two additional tests with other genotypes gave showed positive skewness (tail to the right). The lognormal distribution the same trends.