Annual Report: 2005

Evaluation of Sunflower Germplasm for Resistance to Sclerotinia Diseases

Principal Investigator:
Dr. Thomas J. Gulya, Jr.
USDA-ARS-RRVARC
Fargo, ND

2006 Annual Report:
This report serves to document research conducted under a specific cooperative agreement between ARS and North Dakota State University, Department of Plant Pathology.  Additional details of research can be found in the report for the parent project 5442-22000-022-00D Development of Genetically Diverse, Disease Resistant Sunflower Germplasm.  The most significant accomplishments during the past year were (1) assessment of the stalk rot resistance of commercial hybrids to produce statistically sound data, resulting in publication in an extension bulletin, and (2) continued evaluation of USDA breeding material to produce both oilseed and confection parental germplasm with resistance to both stalk rot and head rot.

Specifically, 85 commercial hybrids, plus four checks, were grown at five locations and artificially inoculated with S. sclerotiorum for stalk rot.  Three locations produced statistically sound data, with the 85 hybrids ranging in stalk rot incidence from 8% to 71%, averaged over the three locations.  The USDA-ARS hybrid HA 412 x RHA 409 was the most resistant entry.  Stalk rot incidence exhibited a continuous range from most resistant to most susceptible, as would be expected with a quantitative, polygenic trait.  Twenty-eight of the 85 hybrids were not statistically different than HA 412 X RHA 409, with stalk rot ranging from 12 to 26%.  Of this highly resistant group, 15 of the 28 hybrids are currently on the market, with the remainder being experimentals.  Concerning the USDA breeding effort, the program was expanded to include confection as well as oilseed types.  Test crosses using three, divergent, long-seeded confection lines were made in 2005 and tested for stalk rot and head rot resistance in 2006.  Confection and oilseed lines displaying high levels of stalk rot and head rot resistance are being evaluated in subsequent years, with the objective of combining Sclerotinia resistance with downy mildew resistance, herbicide tolerance, and high oleic acid content.

Contact Information:
Dr. Thomas J. Gulya, Jr., Research Plant Pathologist
USDA-ARS-RRVARC
Northern Crop Science Laboratory
Sunflower Research Unit
1307 18th Street North
Fargo, ND  58105-5677
701-239-1316