Submitted to: Biological Control
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/10/2003
Publication Date: 10/1/2003
Citation: Khan, N.I., Schisler, D.A., Boehm, M.J., Lipps, P.E., Slininger, P.J. 2004. Field testing of antagonists of Fusarium head blight incited by Gibberella zeae. Biological Control. 29:245-255. Interpretive Summary: Fusarium head blight (FHB) is responsible for extensive damage of wheat in humid and semi-humid regions in the United States and around the world. The fungus that causes most of the damage is particularly devastating because it reduces both the yield and quality of the wheat produced. Control options for this disease are limited. Traditional methods of controlling plant diseases such as resistant wheat cultivars, fungicides and modification of cultural conditions have not been very effective against FHB. At the National Center for Agricultural Utilization Research, we have discovered 7 types of biological control agents (3 bacteria and 4 yeasts) that have shown great promise in reducing FHB in greenhouse studies and in the field on durum wheat. In the current study, we tested these biocontrol agents against FHB on two cultivars of hard red spring wheat and two cultivars of soft red winter wheat in field studies in three states. Biocontrol agents were grown on two types of nutrients in liquid and applied at two concentrations to determine if the effectiveness of the biocontrol agents could be further increased. In most cases, yeast Cryptococcus nodaensis OH182.9 and Cryptococcus sp. OH 181.1 decreased disease severity throughout the study at all locations. The most effective biocontrol agents reduced disease severity by as much as 50-60%. The nutrients used to grow the biocontrol agents or the amount of biocontrol agent used rarely made a difference in how well the biocontrol agents performed. With further research, it seems likely that biological control of FHB will become a useful tool for inclusion in an integrated program for reducing FHB.
Technical Abstract: Fusarium head blight (FHB), primarily caused by Gibberella zeae (anamorph = Fusarium graminearum), is a devastating disease that causes extensive yield and quality losses to wheat and barley throughout the world. Antagonists that suppressed FHB in earlier greenhouse studies were tested in a series of field experiments at different geographical locations in the United States in 1998-2000. In most cases, yeast Cryptococcus nodaensis OH182.9 and Cryptococcus sp. OH 181.1 decreased disease severity throughout the study at all locations. The most effective antagonists reduced disease severity by as much as 50-60%. The influence of antagonist dose varied among the antagonists. The efficacy of some antagonists differed depending on the dose applied, but differences were not necessarily related to a dose response. Antagonist biomass produced in two liquid culture media with differing carbon-to-nitrogen (C:N) ratios suppressed FHB disease severity. On the susceptible winter wheat cultivar Pioneer 2545 at Peoria, IL, in 2000, yeast OH 182.9 reduced disease severity by 60% and by 45%, compared to the buffer control when produced in C:N 11.0 and 6.5 medium, respectively. The influence of C:N ratio of the production medium on antagonist efficacy on cultivar Pioneer varied with the antagonist considered. Antagonists produced using either medium did not reduce disease on resistant winter wheat cultivar Freedom at the Peoria, IL, or Wooster, OH, locations. Biological control of FHB offers a potentially useful tool for inclusion in an IPM program for combating FHB on winter and spring wheats.