Trace element studies on six species of helminthosporium

Trace element studies were carried out on six species of Helminthosporium- H. sativum P. K. B.,H. avenae Eidam, H. teres Sacc., H. oryzae Br. de Haan, H. turcicum Pass., and H. sacchari (Br. de Haan) Butler. The trace element contaminants from glassware, water, basal medium and inoculum were removed by various usual means. In addition, disodium salt of Ethylene diamine tetra acetic acid (EDTA) was used to remove trace elements from glassware and water. Out of the 16 trace elements tested, Fe, Zn and Mn were found essential for the growth of all these species of Helminthosporium; Cu for the growth of H. avenae, H. oryzae, H. turcicum and H. sacchari but not for the growth of H. sativum and H. teres; Mo and Ca for the growth of H. oryzae and H. sacchari but not for the growth of H. sativum, H. avenae, H. teres and H. turcicum. No other trace element was found essential for the growth of any of these fungi. Optimum concentrations in ppm of the essential trace elements for these fungi were as follows: H. sativum: Fe 10.0, Zn 0.0001, Mn 100.0, H. avenae: Fe 1.0; Zn 10.0; Mn 0.1, Cu 0.1;H. teres: Fe 0.01, Zn 10.0, Mn 0.01; H. oryzae: Fe 0.001, Zn 10.0, Mn 0.1, Cu 0.0001, Mo 0.0001, Ca 750.0; H. turcicum: Fe 0.1, Zn 0.1, Mn 1.0, Cu 0.1; H. sacchari: Fe 1.0, Zn 10.0, Mn 100.0, Cu 0.01, Mo 0.0001, Ca 250.0. Concentrations higher than the optimum were inhibitory to the respective fungi