Use of strains of Bacillus isolated in China to suppress take-all and rhizoctonia root rot, and promote seedling growth of glasshouse-grown wheat in Australian soils

Abstract

Several strains of Bacillus subtilis and B. cereus, isolated and selected in China for their ability to promote plant growth and control root disease (yield-increasing bacteria), were tested for their potential to control take-all, caused by Gaeumannomyces graminis var. tritici, and rhizoctonia root rot caused by R. solani AG-8 on wheat seedlings grown in field soils in a glasshouse. Bacillus cereus isolate A47 and B. subtilis B908 consistently reduced the severity of take-all of wheat grown in a sodic acid soil. The amount of disease control was similar to that obtained with the biocontrol isolate Pseudomonas corrugata 2140. B. subtilis B931 was considerably more effective than other bacterial treatments in reducing the severity of rhizoctonia root rot in a calcareous sandy loam soil. Control of rhizoctonia root rot with isolate B931, and also with B. cereus strains A47 and M22 was both substantial and reproducible. Seedling growth promotion effects following bacterial treatment were less consistent than disease control effects. B. subtilis B908 and B. cereus A47-2 and A47-3 gave the most frequent positive growth responses (wheat seedling root weight, shoot weight and shoot length) in the absence of pathogen inoculum. This is the first reported research outside China where these Bacillus isolates have given control of soil-borne root diseases and promoted growth of healthy seedlings under glasshouse conditions.