Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/1995
Publication Date: N/A
Interpretive Summary: Soilborne plant pathogens are major yield-limiting factors in the production of food, fiber and ornamental crops. Take- all, caused by the fungus Gaeumannomyces graminis var. tritici (Ggt), is the most important root disease of wheat in the U.S. and worldwide. Interest in the use of microorganisms to suppress soilborne plant pathogens has been stimulated in recent years by trends in agriculture toward greater sustainability and public concerns about hazards associated with the use of chemical pesticides. Take-all can be suppressed by a variety of soil microorganisms including saprophytic fungi such as Trichoderma spp. and bacteria such as fluorescent Pseudomonas spp. that are associated with the roots of wheat. The purpose of this research was to assess the biocontrol activity of Trichoderma koningii against take- all and to determine the feasibility of combining fluorescent Pseudomonas spp. with Trichoderma in order to enhance biocontrol activity. Trichoderma koningii alone provided substantial control of take-all in both growth chamber and field experiments. Combining T. koningii with certain fluorescent pseudomonas spp. enhanced the performance in growth chamber but not field tests. These results demonstrated that each biocontrol agent is effective at different stages of take-all development. These findings are useful to ongoing efforts to develop commercially viable biocontrol agents for plant pathogens.
Technical Abstract: Trichoderma koningii reduced the severity of take-all of wheat caused by Gaeumannomyces graminis var. tritici (Ggt) in growth-chamber experiments and slightly enhanced the growth of wheat in the absence of Ggt. In field trials, T. koningii applied to the seed furrow increased the yield of spring wheat by 65% at Mt. Vernon, WA, and reduced crown root infection by Ggt on winter wheat by 40% at Pullman, WA. T. koningii was generally more suppressive of take-all than Pseudomonas fluorescens Q29z-80. In field trials, the combination of T. koningii and Q29z-80 increased yield compared to Q29z-80 alone but was not different from T. koningii alone. In growth chamber experiments, combination of T. koningii and any of six bacterial treatments provided substantially better than the bacterial treatments applied alone. Combinations of T. koningii and only three bacterial treatments provided greater suppression of take-all than T. koningii alone