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Prevalent Races of Puccinia helianthi in Cultivated Sunflower on the Texas High Plains.. S. M. Yang, USDA-ARS, Conservation and Production Research Laboratory, Bushland, TX 79012. T. Gulya, USDA-ARS, North Dakota State University, Fargo 58105. Plant Dis. 70:603. Accepted for publication 28 January 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-603c.

A survey of Puccinia helianthi Schw. races occurring on cultivated sunflower (Helianthus annuus L.) in 12 commercial fields on the Texas High Plains was conducted during 1982 and 1984. Races were identified by the use of three standard Canadian differentials: S 37-388, CM 29-3, and CM 90RR (1). In 1982, only race 4 was found in all 12 fields. In 1984, race 4 occurred alone in seven fields and in conjunction with race 3 in one field. The sunflower cultivars commonly grown on the Texas High Plains—Sungro 342, Sungro 378, Sungro 380A, TT 894A, and WAC 318—are susceptible to races 3 and 4 found in the Texas High Plains. These were originally selected for field resistance to rust in the tri-state area of Minnesota, North Dakota, and South Dakota, where sunflower rust races 2, 3, and especially 1 predominate (2). We suggest that sunflower cultivars to be grown on the Texas High Plains should also be screened for resistance to races 3 and 4.