The effect of inoculation of seed with antagonists of Rhizoctonia solani on the growth of wheat

Abstract

Biological control of Rhizoctonia solani on wheat by seed inoculation with microorganisms was investigated. Initially inoculants were selected from bacteria and actinomycetes isolated from two soils and screened for antagonism to R. solani on agar. Of 148 isolates tested on agar, 96 were antagonistic to R. solani and of these 42 were added to pasteurized soil sown with peppers and inoculated with the pathogen. Seven isolates which controlled disease were screened further as seed inoculants of wheat in pasteurized and field soils inoculated with R. solani.

Four inoculants, viz. Streptomyces griseus 2-A24 and three Bacillus subtilis isolates 1-B80, 1-B77 and 1-B68, significantly reduced symptoms caused by R. solani and also increased grain yield and dry matter of wheat. S. griseus 2-A24 and B. subtilis 1-B80 increased grain yield by 30% over controls. The magnitude of these differences suggests that biological control and growth stimulation are involved in yield increases.