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Evaluating management of stripe rust in North Dakota with foliar applied fungicides and host resistance

Bryn Halley: North Dakota State University

<div>Stripe rust (yellow rust; Yr) caused by <em>Puccinia striiformis </em>f. sp. <em>tritici</em> is a cool season disease that can cause yield limitations in North Dakota (ND). Recently, Yr has been detected earlier in the wheat growing season in the Northern Great Plains of the USA. In ND, Yr has been documented as early as Feekes 2 (tillering) in hard red spring wheat. This has increased the risk for economic losses in spring wheat, warranting updated management recommendations. The objective of the research was to determine the effect of fungicide timing in combination with host resistance for Yr management. Five field trials were conducted at three ND locations in 2016-2017. Each trial was a randomized complete block design with a split-plot arrangement. Main plots were three spring wheat varieties varying in Yr susceptibility. Sub-plots were four common fungicide application timing treatments, including a non-treated control, a Feekes 9 (flag leaf) application, a Feekes 10.51 (early-anthesis) application, and sequential application of both Feekes 9 and 10.51. Severity diagrams and area under disease progress curves were generated with data from visual assessments of plants for Yr. Plots were harvested and yield, test weight, and DON were determined. Under high disease pressure, fungicide applications at Feekes 9 and Feekes 10.51 on a susceptible variety resulted in disease control values in excess of 90%. Results will aid in updating management recommendations for ND wheat growers.</div>