Assessing the contribution of ethaboxam in seed treatment cocktails for the management of metalaxyl-resistant Pythium sp. in Pacific Northwest spring wheat production

Authors: WHITE, DAVID - University Of Idaho; Chen, Weidong; SCHROEDER, KURTIS - University Of Idaho

Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/17/2018
Publication Date: 9/14/2018
Citation: White, D., Chen, W., Schroeder, K. 2018. Assessing the contribution of ethaboxam in seed treatment cocktails for the management of metalaxyl-resistant Pythium sp. in Pacific Northwest spring wheat production. Crop Protection. 115:7-12. https://doi.org/10.1016/j.cropro.2018.08.026.
DOI: https://doi.org/10.1016/j.cropro.2018.08.026

Interpretive Summary: Metalaxyl-resistant Pythium spp. have been an emerging problem for chickpea production in the Pacific Northwest, and an alternative fungicide ethaboxam has gained regional interests in managing the metalaxyl-resistant Pythium. However, the effect of the metalaxyl-resistant Pythium and the alternative fungicide on spring wheat is still unknown. Pythium root rot and damping-off have long been observed as an annual problem, particularly in spring planted crops including cereal and pulse crops. This research evaluated the effectiveness of ethaboxam in combination with two other seed treatment cocktails on spring wheat in controlling metalaxyl-resistant Pythium over three growing seasons in the Pacific Northwest. Based on evaluation of emergence, seedling characteristics, plant height, yield and test weight, the addition of ethaboxam to metalaxyl-containing seed treatment blends consistently increased emergence and yield of spring wheat for all three years compared to seed treatment blends containing metalaxyl. However, no correlation was found between yield and test weight for any treatment for any year. The research showed that ethaboxam can improve disease control in spring wheat production when applied as a seed treatment in combination with metalaxyl, specifically in the presence of metalaxyl-resistant Pythium spp.

Technical Abstract: Hard red spring wheat is an important crop in the Pacific Northwest and is a component of a three-crop rotation involving soft white winter wheat and cool season pulse crops such as pea and chickpea, or canola. Pythium root rot and damping-off have long been observed as an annual problem, particularly in spring planted crops. As such, a seed treatment that includes metalaxyl is very common. Recently, an increase in the incidence of Pythium damping-off highlighted that there is an emerging population of Pythium spp. that are resistant to traditional seed treatments containing metalaxyl. The use of alternative chemistries to manage Pythium root rot and damping-off has gained regional interest to increase crop health and improve yields. The effectiveness of ethaboxam in a seed treatment was evaluated in combination with two other seed treatment cocktails in controlling metalaxyl-resistant Pythium in replicated field experiments of spring wheat over three growing seasons in Northern Idaho. Emergence, seedling characteristics, plant height, yield and test weight were assessed. The addition of ethaboxam to metalaxyl-containing seed treatment blends consistently increased emergence and yield of spring wheat for all three years compared to seed treatment blends containing metalaxyl. However, there was no correlation between yield and test weight for any treatment for any year. First leaf length, an indirect measure of early season Pythium damage, was longest in seed treatments containing ethaboxam and the average number of tillers was lower likely due to increased emergence than untreated seed. These results indicate that ethaboxam can improve disease control in spring wheat production when applied as a seed treatment in combination with metalaxyl, specifically in the presence of metalaxyl-resistant Pythium spp.