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Poster: Biology & Disease Mgmt: Chemical Control


Efficacy of Oxathiapiprolin toward Phytophthora sojae and Phytophthora sansomeana
A. VARGAS (1), M. Eyre (1), A. Dorrance (1) (1) The Ohio State University, U.S.A.

Poor crop stand establishment caused by soil-borne pathogens is very common in soybean fields in Ohio. Metalaxyl has been the most commonly used fungicide to control Phytophthora and Pythium species in soybean. However, several studies have reported an increase of insensitivity to metalaxyl in Phytophthora and Pythium populations in Ohio. Therefore, alternative fungicides should be tested for efficacy towards Phytophthora and Pythium species. The objective of this experiment was to determine the efficacy of oxathiapiprolin in reducing the growth of Phytophthora sojae and Phytophthora sansomeana in soybean. A total of 28 isolates collected from infested fields were evaluated using amended agar Petri dishes with 5 different concentrations of oxathiapiprolin. Sensitivity of each isolate was evaluated by estimating the diameter of mycelial growth on each Petri dish and comparing it to the control. Results from preliminary data show that oxathiapiprolin treatments reduced P. sojae and P. sansomeana mycelial growth and mean values varied among isolates. Eight isolates did not grow at 0.01 µg active ingredient/ml. Based on these results could be used to manage seed rot caused by P. sojae and P. sansomeana.