Oral Technical Session: Chemical Control 2

128-O

Efficacy of ethaboxam toward species of Phytophthora and Pythium.
A. E. DORRANCE (1), M. L. Ellis (2), D. McDuffee (3), K. Arthur (4)
(1) The Ohio State University, Wooster, OH, U.S.A.; (2) The Ohio State University, OARDC, Wooster, OH, U.S.A.; (3) Valent U.S.A. Corporation, Indianapolis, IN, U.S.A.; (4) Valent U.S.A. Corporation, Plano, TX, U.S.A.

Stand loss due to seed and seedling pathogens is very common in Ohio for both corn and soybean. In many cases Phytophthora or Pythium were identified as the causal agent. One strategy to manage these pathogens is the use of seed treatments. The efficacy of ethaboxam was evaluated towards Phytophthora sojae, P. sansomeana, and eight different Pythium spp. in amended agar assays. This fungicide was also evaluated for efficacy as a soybean seed treatment in greenhouse assays, and field trials. In amended agar and greenhouse assays, ethaboxam provided greater, similar, or was less efficacious than metalaxyl towards the isolates of the different Phytophthora and Pythium spp. In field studies, seed treated with 7.5 to 15 g a. i./100 kg of seed had significantly higher stands and yield in 2008 and 2010 for the moderately susceptible variety. The moderately resistant variety had significantly higher stands and yield in the same trials when ethaboxam was applied at the same rates in 2010 and 2011 at two locations. Ethaboxam applied to soybean seed as a seed treatment will provide another tool to manage seedling diseases caused by Phytophthora and Pythium spp.
Keywords: Oomycete, Cereals-Grains, Soybean