Integrated Crop Management News

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Phytophthora has many races and the Rps-1k gene confers resistance to many of them. The 1k gene has been widely bred into soybeans to manage Phytophthora root rot. It has been very effective in management of Phytophthora; however, this summer we have received many reports of Phytophthora root rot on soybean varieties with the 1k gene. Recently, we have observed an increased prevalence of a new race in Iowa that can overcome the 1k gene called race 25. Growers are wondering why the 1k gene is not working, and if they can test to determine whether their fields contain race 25.

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Iowa State University



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