Trace element studies on some pathogenic fungi

Trace element studies were carried out on five pathogenic fungi—Cercospora hibiscina Ellis and Everh.,C. withaniae H. and P. Syd.,C. crotalariae Sacc.,Monochaetia sp., andPestalotia theae Sawada. The trace element contaminants from glassware, basal medium, water, glucose and inoculum were removed by various usual means. In addition, EDTA was used for the removal of trace elements from glassware and water. Out of the 15 trace elements tested, Fe, Zn, Cu and Mn were found to be essential for the growth of these five fungi while Mo was found essential only for the growth ofC. crotalariae andMonochaetia sp. No other trace element was found to be essential for any of these fungi. Optimum concentrations in ppm of essential trace elements for these fungi were found to be as follows:C. hibiscina: Fe 0·2, Zn 0·01–0·1, Cu 0·01 and Mn 1·0;C. withaniae: Fe 1·0, Zn 1·0, Cu 0·1 and Mn 10·0;C. crotalariae: Fe 0·01, Zn 10·0, Cu 0·001, Mn 0·1, and Mo 0·001;Monochaetia sp.: Fe 1·0, Zn 0·1, Cu 0·1, Mn 0·1 and Mo 0·01; andPestalotia theae: Fe 10·0, Zn 0·1, Cu 0·01 and Mn 0·01. Concentrations higher than the optimum were inhibitory to the respective fungi.