Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: May 4, 2009
Publication Date: June 30, 2009
Citation: Block, C.C., Gulya Jr, T.J., Marek, L.F. 2009. Evaluation of Wild Sunflower Species for Resistance to Sclerotinia Stalk Rot [abstract]. Phytopathology. 99:S13. Technical Abstract: One of the most important diseases affecting sunflower production in the United States is stalk rot caused by Sclerotinia sclerotiorum. Genetic resistance to Sclerotinia has gradually improved in commercial sunflower cultivars, but better levels of resistance are still needed. A greenhouse screening method was developed, using soil-applied Sclerotinia-infested millet as inoculum. Greenhouse screening helps to facilitate the rapid screening of much larger plant populations than could be managed in field trials. With this approach, susceptible germplasm can be filtered out, making better use of the follow-up field trials. In 2008, 255 accessions were evaluated in the greenhouse, including all available accessions from the diploid annual species of H. argophyllus, H. debilis, H. exilis, H. neglectus, and H. praecox, 45 accessions of wild H. annuus and five accessions from the perennial species, H. resinosus. Accessions with superior wilt resistance were identified in all species except for H. exilis. Field trials showed that the three most resistant accessions were H. resinosus (PI 650079 and PI 650082) and H. argophyllus (PI 649863), with 100% and 94% survival, respectively. These findings suggest that resistant germplasm can be readily identified that could contribute toward improved Sclerotinia resistance in cultivated sunflower.