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Wind-Blown Soil in the Epidemiology of Bacterial Leaf Spot of Alfalfa and Common Blight of Bean. L. E. Claflin, Former Graduate Research Assistant in Plant Pathology, USDA, Kansas State University, Manhattan 66506, Present address of senior author: Department of Plant Pathology, Montana State University, Bozeman 59715; D. L. Stuteville(2), and D. V. Armbrust(3). (2)(3)Plant Pathologist, and Research Soil Scientist, USDA, respectively, Kansas State University, Manhattan 66506. Phytopathology 63:1417-1419. Accepted for publication 4 June 1973. DOI: 10.1094/Phyto-63-1417.

Potted, healthy alfalfa and been plants were placed in a laboratory wind tunnel and exposed to naturally infested dry field soil blown at regulated air speeds. The plants were then kept on a greenhouse bench for 10-14 days, and the resulting incidence of bacterial leaf spot of alfalfa and common blight of bean was determined. Disease incidence increased as wind speed and exposure time increased and was greater in the row nearest the wind source. Lesions were mostly confined to the lower 10-cm of plant shoots where the blowing particles were most concentrated. Lesions on stems were confined to their windward side. Bacterial leaf spot incidence increased from 6% after 3-min exposure to soil blown 9.4 m/sec to 26% after 5-min exposure at 13.9 m/sec. Blight incidence in 2-week-old bean plants from exposure to soil blown 13.9 m/sec for 3 and 5 min was 25 and 55%, respectively.

Additional keywords: wind, Xanthomonas alfalfae, Xanthomonas phaseoli.