VIEW ARTICLE

Ecology and Epidemiology

Horizontal Dispersal of Urediospores of Puccinia recondita f. sp. tritici and P. graminis f. sp. tritici from a Source Plot of Wheat. M. G. Eversmeyer, Research plant pathologist, USDA, SEA, AR, Department of Plant Pathology, Kansas State University, Manhattan 66506; C. L. Kramer, professor, Division of Biology, Kansas State University, Manhattan 66506. Phytopathology 70:683-685. Accepted for publication 9 January 1980. 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-70-683.

Kramer-Collins volumetric samplers were used to sample air 6 m above ground level to measure downwind dispersal of Puccinia recondita and P. graminis urediospores from a wheat plot. The rate of decrease in the average numbers of P. recondita and P. graminis urediospores trapped per cubic meter of air sampled in the wheat canopy and at 6 m above ground level 60, 120, and 180 m downwind from the wheat plot was calculated by regression analysis. Beta coefficients (b) of urediospore dispersal per meter downwind were calculated by using the log₁₀ of the spore concentration within the canopy as the source concentration. Beta coefficients of –0.006 for P. recondita and –0.004 for P. graminis were calculated. Spore-trapping stations in most epidemiological studies have been located just above the canopy or 1 m above ground level. Beta coefficients of –0.001 for P. recondita and –0.002 for P. graminis were calculated by using the log₁₀ of the spore concentration at 1 m as the source concentration. Virtual point source strengths were calculated and regression analysis resulted in r² values of 0.88 for P. recondita and 0.87 for P. graminis. Constants for the slope of the regression lines (b) were –0.017 and –0.015, respectively. Downwind spore concentrations predicted by the use of virtual point source strengths were not significantly different than measured downwind spore concentrations.