|Gulya Jr, Thomas|
|MAREK, LAURA - Iowa State University|
Submitted to: ARS Sclerotinia Initiative Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 1/20/2011
Publication Date: 1/21/2011
Citation: Block, C.C., Gulya Jr, T.J., Marek, L. 2011. Evaluation of Wild Helianthus Species for Resistance to Sclerotinia Stalk Rot. ARS Sclerotinia Initiative Annual Meeting. p. 13.
Technical Abstract: The objective of this project is to identify new sources of resistance to Sclerotinia stalk rot in wild sunflower germplasm. The USDA collection contains 1,365 wild annual accessions and 805 perennials. Plants are initially tested under high disease pressure in the greenhouse. Accessions considered to be potential sources of resistance are further tested in the field. In 2009-10, all available accessions of H. anomalus, H. agrestis, H. bolanderi, H. deserticola, and H. paradoxus were evaluated. Helianthus agrestis was impressive with 99.5% plant survival. Unfortunately, this species is incompatible with cultivated sunflower. The other four species were fairly susceptible. We evaluated a geographic cross-section of 60 wild H. annuus accessions to determine if a particular region (from ND to south Texas) might have a higher percentage of resistant germplasm. None of the accessions performed better than the best check, but six of the top 10 came from south Texas. Twenty-seven entries were planted in a field trial at Staples, MN along with F1 crosses of the susceptible inbred HA89 with H. argophyllus, H. petiolaris and H. praecox. Unfortunately, frequent heavy rains severely limited Sclerotinia disease development and it was not possible to verify differences between the susceptible and resistant lines. Greenhouse screening of perennials started with H. pauciflorus, H. californicus, H. resinosus, and H. salicifolius. All of these species showed remarkable resistance. Seven of 10 H. californicus accessions had 100% plant survival and the rest were above 95%. Twenty-two of the 31 H. pauciflorus accessions had 80% or better plant survival. Among H. resinosus, 8 of 14 accessions had 100% survival and 11 of 14 accessions were at or above 90%. For H. salicifolius, 7 of 14 accessions had 100% survival and 12 of 14 were at or above 90%.