<i>Trichoderma harzianum</i>: A Biocontrol Agent Effective Against <i>Sclerotium rolfsii</i> and <i>Rhizoctonia solani</i>

Abstract

An isolate of <i>Trichoderma harzianum</i> capable of lysing mycelia of <i>Sclerotium rolfsii</i> and <i>Rhizoctonia solani</i> was isolated from a soil naturally infested with those pathogens. In culture, <i>T. harzianum</i> grew better than <i>S. rolfsii</i> and invaded its mycelium under growth conditions adverse to the pathogen; eg, high pentachloronitrobenzene concentrations, high pH levels, or low temperatures. Under greenhouse conditions, incorporation of the wheat-bran inoculum preparation of <i>T. harzianum</i> in pathogen-infested soil significantly reduced bean diseases caused by <i>S. rolfsii, R. solani</i>, or both, but its biocontrol capacity was inversely correlated with temperature. The wheat bran preparation of <i>T. harzianum</i> increased growth of bean plants in a noninfested soil and it controlled <i>S. rolfsii</i> more efficiently than a conidial suspension of the same antagonist. An uninoculated wheat bran preparation increased disease incidence. In naturally infested soils, wheat bran preparations of <i>T. harzianum</i> inoculum significantly decreased diseases caused by <i>S. rolfsii</i> or <i>R. solani</i> in three field experiments with beans, cotton, or tomatoes, and they significantly increased the yield of beans.