Oral: Plant Pathologists of the Future: Showcasing the Top Graduate Students from APS Division Meetings
Identification of Helianthus accessions resistant to Plasmopara halstedii (downy mildew) and Puccinia helianthi (rust).
R. HUMANN (1), T. Gulya (2), M. Acevedo (3), L. Marek (4), J. Jordahl (3), S. Meyer (3), S. Markell (3) (1) North Dakota State University, U.S.A.; (2) USDA-ARS Sunflower Research Unit (retired), U.S.A.; (3) North Dakota State University, U.S.A.; (4) USDA-
Downy mildew (Plasmopara halstedii (Farl.) Berl and de Toni) and rust (Puccinia helianthi Schwein.) are economically important diseases of sunflower (Helianthus annuus L.) in the Northern Great Plains. Genetic resistance can be an effective tool for managing both diseases, but the identification of new sources of resistance is needed. Historically, a disproportionate amount of resistance genes have been identified in germplasm originating from Texas. The objective of this study is to identify new potential sources of resistance to P. halstedii and P. helianthi. One hundred eighty-two H. annuus and 33 H. argophyllus accessions originating from Texas were obtained from the USDA North Central Regional Plant Introduction Station and screened to both pathogens in a greenhouse environment. Ninety-three H. annuus and 23 H. argophyllus accessions were resistant to commonly detected P. halstedii races, of which, 18 H. annuus and three H. argophyllus accessions were resistant to highly virulent races. Seventy-one H. annuus and 33 H. argophyllus accessions were resistant to commonly detected P. helianthi races, of which, 41 H. annuus and five H. argophyllus accessions were resistant to highly virulent races. Seven H. annuus and three H. argophyllus accessions resistant to both pathogens were identified, two of which were among the most resistant accessions to both pathogens.