Antagonism between Gliodadium roseum, Trichoderma harzianum, or Trichothecium roseum and Phytophthora megasperma f. sp. glydnea

Abstract

The antagonism between Gliodadium roseum, Trichoderma harzianum, or Trichothecium roseum and Phytophthora megasperam f. sp. glycinea (Pmg), cause of Phytophthora rot of soybeans (Glycine max), was studied. G. roseum, T. harzianum, and 17 isolates of T. roseum were grown separately on modified Czapek-Dox medium (MCD) in the dark for 25 days at 25 °C. Culture filtrates of T. roseum at 0.5% and 20.0% concentrations inhibited mycelial growth of Pmg at 3.1% and 90.4%; and those of G. roseum at −0.7% and 44.0%; and of T. harzianum at 0.7% and 46.0%, respectively. Culture filtrates of T. roseum at 0.5% concentration inhibited zoosporangenesis of Pmg at 98.0% and at 1.0% concentration prevented it. Culture filtrates of G. roseum and T. harzianum at 5% concentration significantly (P=0.05) inhibited zoosporangenesis of Pmg, but differences were not significant from that on MCD. Culture filtrates of 17 isolates of T. roseum inhibited mycelial growth and zoosporangenesis of Pmg at different percentages with different concentrations with those of isolate 9 showing the greatest inhibition of both. Mycelial growth of most of 16 races of Pmg was prevented at 10% concentration of the culture filtrates of isolate SS-2 of T. roseum, and all 16 races, except race 6, was prevented at 20% concentration. Zoosporangenesis of all races of Pmg was prevented at 2% the culture filtrate of SS-2. Culture filtrates of SS-2 inhibited zoosporangenesis of Pmg in soil.