VIEW ARTICLE

Ecology and Epidemiology

Analysis of Recent Oat Stem Rust Epidemics. A. P. Roelfs, Research plant pathologist, Cereal Rust Laboratory, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, University of Minnesota, St. Paul 55108; D. L. Long, plant pathologist, Cereal Rust Laboratory, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, University of Minnesota, St. Paul 55108. Phytopathology 70:436-440. Accepted for publication 7 November 1979. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1980. DOI: 10.1094/Phyto-70-436.

An oat stem rust epidemic occurred in the eastern Dakotas and western Minnesota in 1977. Because the pathogen races generally have been virulent on the commercial cultivars during the past 38 yr, this epidemic was chosen as a model disease to investigate for the purpose of making long-range disease forecasts. Temperatures and rainfall frequency and amount were above normal throughout the 1977 epidemic. Thus, these factors were examined to see if they were associated with other epidemics during a 38-yr period for Minnesota, South Dakota, and North Dakota. However, little relationship was found between estimated percentage of yield loss and the minimum or maximum temperatures for May, the period May through July, or the mean frequency or amount of precipitation for the same periods. Date of onset of rust in an area was related to the estimated yield losses, and explained about 20–40% of the variation in estimated loss.