Integrated Management of Stripe Rust and Overwintering of Puccinia striiformis f. sp. tritici in Wisconsin

Puccinia striiformis f. sp. tritici (Pst) is the causal agent of stripe rust and is one of the most problematic pathogens of winter and spring wheat in the United States. Planting resistant cultivars and applying foliar fungicides are common management practices to control this pathogen. In this 2-year study, two fungicides applied at three growth stages were tested on three soft red winter wheat cultivars varying in levels of resistance to stripe rust. Both fungicides (prothioconazole + tebuconazole and pyraclostrobin) applied at Feekes 8 and 10 reduced disease index and increased yield compared with the nontreated control in susceptible ('Pro Seed 420') and moderately susceptible ('Kaskaskia') cultivars. The highly resistant cultivar (Pro Seed 380') had the greatest yields, and fungicide treatments had no effect on disease levels or yield. In an accompanying study, Pst was found to survive over the 2016 to 2017 winter on the susceptible cultivar Pro Seed 420. This study confirmed that resistance and properly timed fungicide applications play a crucial role in managing stripe rust on winter wheat. This study also demonstrated that Pst can overwinter in Wisconsin, and the impact of this occurrence should be examined further.