Nutritional and environmental factors affecting growth and antifungal activity of a sterile red fungus against Gaeumannomyces graminis var. tritici

Abstract

Growth and antifungal activity of a sterile red fungus against Gaeumannomyces graminis var. tritici (the take-all fungus) in vitro was greatly influenced by nutritional and environmental conditions. The utilization by the sterile red fungus of various carbon and nitrogen sources differed considerably at pH 5.5 and 6.5. Maximum growth of the sterile red fungus occurred when pectin was supplied as the carbon source at both pH levels. As nitrogen sources, NH4H2PO4 supported maximum growth at pH 5.5, whereas Ca(NO3)2 was the best at pH 6.5. Pectin strongly enhanced the antifungal activity of the sterile red fungus towards the take-all fungus as did Ca(NO3)2 supplied as a N source. There was, however, little or no antagonism in the presence of calcium citrate, arabinose, leucine, or arginine. In general, antagonism was optimal at 20 °C and at pH 5.5. Key words: sterile red fungus, Gaeumannomyces graminis var. tritici, biological control.