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ARS Home » Pacific West Area » Corvallis, Oregon » Forage Seed and Cereal Research Unit » Research » Publications at this Location » Publication #206729
Title: FIELD EVALUATION OF THE USDA RUST MODEL – YEAR II

Author
item GINGRICH, G - OREGON STATE UNIVERSITY
item MELLBYE, M - OREGON STATE UNIVERSITY
item Pfender, William

Submitted to: Seed Production Research at Oregon State University
Publication Type: Experiment Station
Publication Acceptance Date: 3/31/2006
Publication Date: 4/30/2006
Citation: Gingrich, G.A., Mellbye, M.E., Pfender, W.F. 2006. Field evaluation of the USDA rust model – year II. Seed Production Research at Oregon State University. EXT CrS, 4/06 P 27-30.

Interpretive Summary: A large-plot field experiment was conducted to evaluate the use of a mathematical epidemic model in optimizing fungicide sprays to manage stem rust disease of perennial ryegrass seed crops. Each replicate plot in the experiment was 300 feet long and 24 feet wide, so that typical grower equipment could be used for harvesting. Fungicide applications were scheduled either by standard (calendar-based) methods, or by reference to the stem rust epidemic model which is accessible on an internet website. The experiment was conducted at two different locations. At one location, the model gave similar spray decisions to the standard method, and there was no significant difference in yield or economic return between the model and standard methods. At the other location however, use of the model resulted in a single spray application instead of two sprays. Yield was not significantly different between the standard and model treatments, so the lower cost of fungicide for the model treatment resulted in a significantly higher return per fungicide dollar invested than in the standard fungicide treatment.

Technical Abstract: A randomized complete block field experiment with three replications was conducted to assess stem rust development and seed yield in perennial ryegrass receiving different fungicide treatments. The check treatment received no fungicide, standard treatments received fungicide applications that varied by material but not timing, and a "model" treatment received fungicide applications with timing determined by reference to the ARS stem rust model that is available on an internet website. Each replicate plot was 24 X 300 ft in size, to allow harvest using grower equipment. A weigh wagon was used to measure seed yield from each plot. The experiment was conducted at two locations in the Willamette Valley. The results at one location showed no difference in number of fungicide applications between the standard and model treatments, and no significant yield difference. At the other location, the model treatments used only one fungicide application whereas the other treatments used two applications, so the rust management cost was lower for the model treatment. Yield was not significantly different among treatments, so the return per dollar invested was better for the model treatment ($5.47) than for the others (less than $1.00) at this location.