Weather variables associated with infection of lettuce by downy mildew (Bremia lactucae) in coastal California

Weather conditions and downy mildew (Bremia lactucae) development were monitored in 13 commercial lettuce fields in the central coast production areas of California during 1991 and 1992. Days on which infection likely had occurred were identified based on observations of the appearance of new lesions combined with quantitative information about the length of the latent period of the disease. Univariate (Kolmogorov-Smirnov tests) and multivariate (stepwise discriminant analysis) procedures were applied to statistically differentiate infection days from days on which infection had not occurred and to characterize infection days in terms RACT of weather [...]