Antagonist Cryptococcus flavescens OH 182.9 3C colonization of wheat heads when applied with triazole fungicides and the effect on scab
D. A. SCHISLER (1), P. A. Paul (2), M. J. Boehm (3), C. A. Bradley (4), C. A. Dunlap (1)
(1) USDA ARS MWA NCAUR, Peoria, IL, U.S.A.; (2) The Ohio State University, OARDC, Wooster, OH, U.S.A.; (3) Ohio State University, Columbus, OH, U.S.A.; (4) University of Illinois, Urbana, IL, U.S.A.
Phytopathology 101:S160

Integrated pest management (IPM) is the best available approach for reducing Fusarium head blight (FHB) and the mycotoxin deoxynivalenol (DON) in grain. Utilizing the effective FHB biological control agent Cryptococcus flavescens OH 182.9 (NRRL Y-30216) as part of an IPM approach against FHB is understudied. Trizole fungicides such as prothioconazole (PTC) used alone (Proline) or in combination with tebuconazole (Prosaro) are effective against FHB, but their use generally is not recommended after wheat anthesis to control late infections. A PTC-tolerant variant of OH 182.9 (OH 182.9 3C) in a tank mix with a fungicide or applied after flowering, could reduce DON by establishing populations that reduce late DON-producing infections by Fusarium graminearum. In a two year study, the colonization of glume and lemma tissues by OH 182.9 3C was determined when the agent was applied alone or in combination with a fungicide at or seven days after wheat flowering. For all treatment combinations, the population of OH 182.9 3C represented 50–95% of the total microbial population recovered from both glume and lemma tissues from 8 to 11 days after flowering, demonstrating the competitive success of the strain. While the application of strain OH 182.9 3C at times reduced (P < 0.05, FPLSD) FHB and/or DON, combinations of fungicide and antagonist were rarely significantly more effective than either component used alone for the doses tested.