Submitted to: National Fusarium Head Blight Forum Proceedings
Publication Type: Proceedings
Publication Acceptance Date: December 1, 2010
Publication Date: December 7, 2010
Citation: Schisler, D.A., Pierce, P., Boehm, M.J., Bradley, C.A., Dunlap, C.A. 2010. Colonization of wheat heads by antagonist Cryptococcus flavescens OH 182.9 when applied alone or in combination with different concentrations of Prosaro® and the effect on Fusarium head blight development in field-grown wheat. Proceedings of the National Fusarium Head Blight Forum. p. 98-102. Technical Abstract: The significant and consistent reduction of Fusarium head blight (FHB) and deoxynivalenol (DON) contamination of wheat and barley remains elusive though research results indicate that utilizing an integrated pest management approach achieves the greatest level of disease/toxin control. The use of yeast biological control agent Cyptococcus flavescens OH 182.9 (NRRL Y-30216) as part of an integrated management strategy against FHB is understudied yet has the potential to contribute to the reduction of FHB and DON. The fungicides prothioconazole (PTC) and tebuconazole (TEB) are effective against FHB but can not be applied later than wheat anthesis. Experiments were conducted to quantify OH 182.9 3C colonization of wheat head tissues when this PTC+TEB tolerant variant of OH 182.9 was applied alone or in combination with a fungicide containing PTC+TEB either at or seven days after wheat flowering. The development of FHB was also evaluated in field grown soft red winter wheat for the same treatments applied in the colonization work. By 184 h after inoculation at flowering, OH 182.9 3C made up >50% of the recoverable microflora, when used alone or in combination with the label rate of the PTC+TEB fungicide, demonstrating for a second year the propensity of OH 182.9 3C to aggressively compete in colonizing infection court tissues on wheat heads. The reduction of FHB disease associated with the various treatments supported the observation that the population of OH 182.9 C3 on infection court tissues was not inhibited by the presence of PTC+TEB. As was the case in an earlier field study, fungicide tolerant variant 3C of OH 182.9 often exhibited efficacy in reducing FHB and mixed results in enhancing the performance of the PTC+TEB fungicide used at full label or reduced rates.