Submitted to: Wheat Newsletter
Publication Type: Research Notes
Publication Acceptance Date: 3/14/2003
Publication Date: 7/1/2003
Citation: Chen, X., Wood, D.A., Moore, M.K., Ling, P., Pahalawatta, V. 2003. Epidemiology and control of wheat rusts in the western united states, 2002. Wheat Newsletter. 49:227-229.
Interpretive Summary: In this paper, we summarized the research conducted in 2002. In 2002, wheat stripe rust occurred in more than 20 states and caused severe yield losses in the south central states, California and the Pacific Northwest. We determined virulence patterns (called races) of more than 300 samples of the wheat stripe rust pathogen from 20 states. A group of new races that were identified first in 2000 were continuing evolving and spreading throughout the wheat growing states. We evaluated more than 8,000 entries of wheat germplasms and breeding lines in the fields and/or the greenhouse. Resistant entries were selected for genetic studies and for developing resistant cultivars. Wheat crosses were made to determine genetics of stripe rust resistance and improve resistance. We were also developing molecular markers for stripe rust resistance and constructing bacterial artificial chromosomal library for cloning resistance genes and determine resistance mechanisms. Efficacy of several fungicides for controlling stripe rust was determined. Through our monitoring stripe rust and distributing information on rust development and management guidance, growers were properly using fungicides to control stripe rust in a timely manner, which saved wheat growers 17 to 30 million dollars in Washington alone and prevented major losses in other states as well.
Technical Abstract: Wheat stripe rust (Puccinia striiformis f. sp. tritici), leaf rust (P. triticina), and stem rust (P. graminis f. sp. tritici) were monitored throughout the Pacific Northwest (PNW) using trap plots and field survey in 2002. Stripe rust was accurately predicted for the PNW using monitoring data and predictive models based on susceptibility of wheat cultivars and environmental factors such as temperature and precipitation. Through collaborators in other states, wheat stripe rust was monitored throughout the United States. Wheat stripe rust occurred from California and the PNW to Georgia and Virginia; and from Louisiana and Texas to Wisconsin and Ohio. Severe yield losses caused by stripe rust occurred in Arkansas, California, and the PNW. In 2002, stripe rust epidemics caused wheat yield losses about eight million bushes plus multi-million dollars on fungicide application in the United States.