Influence of nutrients on growth ofEpicoccum nigrum

Abstract

Epicoccum nigrum is a potential biological control agent for certain plant diseases, such as white mold of bean caused by Sclerotinia sclerotiorum. To provide information that could be used to improve the production and efficacy of E. nigrum, the effects of nutrients, including specific carbohydrate sources and amino acids, on mycelial growth, sporulation, germination of conidia, and elongation of germ tubes were determined. In dual cultures of E. nigrum and S. sclerotiorum, the effects of nutrients on widths of inhibition zones between the two fungi were assessed. Standard mycological media supported faster radial growth than media with single carbohydrate sources and individual amino acids, but glutamic acid combined with maltose or dextrose was similar with respect to stimulation of sporulation when compared with media such as V8 juice and yeast extract agars. Dual culture inhibition zones were greater in certain simple media (dextrose and lysine, sucrose and lysine, and maltose and lysine) than in standard media. For germination and germ tube elongation, sucrose and maltose were superior to most other carbohydrate sources tested, and lysine and glutamic acid were superior amino acid sources. When standard broth media were compared for production of antifungal compounds by E. nigrum, both potato dextrose broth and malt extract broth were superior to Czapek solution. Culture filtrates of E. nigrum grown in potato dextrose broth were more inhibitory towards S. sclerotiorum than filtrates from malt extract cultures.Key words: biological control, white mold, Epicoccum purpurascens, antibiosis.