Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2001
Publication Date: 12/1/2001
Citation: KHAN, N.I., SCHISLER, D.A., BOEHM, M.J., SLININGER, P.J., BOTHAST, R.J. SELECTION AND EVALUATION OF MICROORGANISMS FOR BIOCONTROL OF FUSARIUM HEAD BLIGHT OF WHEAT INCITED BY GIBBERELLA ZEAE. PLANT DISEASE. 2001. v. 85(12). p. 1253-1258. Interpretive Summary: Since 1990, Fusarium head blight (FHB) has caused 3.0 billion dollars of damage to wheat in the United States alone. The fungus that causes the disease, Gibberella zeae, can produce toxins during colonization of grain that reduce grain yield and adversely affect grain quality. Control options for this disease are limited. Registered fungicides can be effective; however, residue and cost concerns are potential problems with chemical usage. Highly resistant wheat cultivars are not widely available. Biological control, though currently not available, would offer another option for reducing FHB. In this study we report on the discovery of seven biocontrol agents that are effective in reducing FHB. Four of these agents were selected because they were able to consume tartaric acid, a compound that could be used in formulating biocontrol agents since G. zeae does not readily consume it. Biocontrol was achieved against three different isolates of the pathogen. Four biocontrol agents reduced disease regardless of the sequence and timing of applying the pathogen and agents to wheat heads. With further research, we anticipate that these biocontrol strains will offer an economically feasible and effective addition to the integrated management of FHB.
Technical Abstract: Gibberella zeae incites Fusarium head blight (FHB), a devastating disease that causes extensive yield and quality losses to wheat and barley. Fifty-four of over 700 microbial strains obtained from wheat anthers utilized tartaric acid when it was supplied as choline bitartrate in liquid culture. Four tartaric acid-utilizing and three non-utilizing strains reduced FHB in initial tests and were selected for further assays. Antagonists were effective against three different isolates of G. zeae when single wheat florets were inoculated with pathogen and antagonist inoculum. All seven antagonists increased 100 kernel weight when applied simultaneously with G. zeae isolate Z3639 (P less than or equal to 0.05). Bacillus strains AS 43.3, AS 43.4, and Cryptococcus strain OH 182.9 reduced disease severity by 77%, 93%, and 56%, respectively. Five antagonists increased 100 kernel weight of plants inoculated with G. zeae isolate DAOM 180378. All antagonists except one increased 100-kernel weight, and four of seven antagonists reduced disease severity (P less than or equal to 0.05) when tested against G. zeae isolate Fg-9-96. In spray inoculation experiments, Bacillus strains AS 43.3 and AS 43.4 and Cryptococcus strains OH 71.4 and OH 182.9 reduced disease severity regardless of the sequence, timing, and concentration of inoculum application (P less than or equal to 0.05). Overall, four of the 54 isolates that utilized tartaric acid in vitro were effective against G. zeae versus only three of 170 isolates tested that did not utilize tartaric acid, demonstrating the usefulness of pre-screening candidate antagonists of FHB for their ability to utilize tartaric acid.