Stability analysis for evaluating the influence of environment on chemical and biological control of white mold (Sclerotinia sclerotiorum) of bean

Fungicide and biological control treatments were evaluated for efficacy in suppressing white mold of bean in six held trials. In all trials, treatment with the fungicide benomyl significantly suppressed disease. In almost all trials, at least one biological control treatment significantly suppressed disease but no biological control treatments provided significant suppression in more than two trials. Stability analyses of the treatment responses in the different environments (e.g., trials) indicated that most treatments responded in a linear manner as environmental conditions became more conducive to disease. AU treatments became less effective as conditions became more conducive for disease but the fungicide treatment provided a relatively stable suppression of disease in all tested environments. The biological control treatments provided a relatively unstable suppression of disease and, in general, were effective only when environmental conditions were less favorable for disease development. The results establish that all of the evaluated disease management practices were responsive to environmental factors present during epidemics of white mold and indicate why biological controls often provide a more variable suppression of disease than fungicides. (C) 1997 Academic Press.