USE OF GAEUMANNOMYCES-GRAMINIS VAR GRAMINIS ALONE AND IN COMBINATION WITH FLUORESCENT PSEUDOMONAS SPP TO SUPPRESS TAKE-ALL OF WHEAT

Gaeumannomyces graminis var. graminis, originally isolated from rice, suppressed take-all of wheat caused by Gaeumannomyces graminis var. tritici in growth chamber studies when applied to the soil. Furthermore, combination treatments consisting of G. g. var. graminis applied to the soil and fluorescent Pseudomonas strains applied to the seed, either 30-84, Q29z-80, Q69c-80, or a mixture of strains (Q2-87 plus Q1c-80 plus Q8d-80 plus Q69c-80), were significantly more suppressive of take-all than either treatment used alone. In a winter wheat field trial at Pullman, Wash., G. g. var. graminis applied to the seed furrow significantly reduced crown root infection by G. g. var. tritici and the strain mixture reduced seminal root infection suggesting differential protection at various stages of disease development. However, in contrast to growth chamber studies the combination of G. g. var. graminis and the strain mixture did not enhance take-all suppression in the field compared with the same treatments used alone.