NUTRITIONAL AND ENVIRONMENTAL-FACTORS AFFECTING GROWTH AND ANTIFUNGALACTIVITY OF A STERILE RED FUNGUS AGAINST GAEUMANNOMYCES-GRAMINIS VAR TRITICI

Growth and antifungal activity of a sterile red fungus against Gaeuman nomyces graminis var. tritici (the take-ail fungus) in vitro was great ly influenced by nutritional and environmental conditions. The utiliza tion 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, NH,H,PO, 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 th e 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 degrees C and at pH 5.5.