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New, Disease Resistant Sunflower Available

By Jan Suszkiw
May 11, 2004

Sunflower breeders seeking new "ammunition" against the fungus Sclerotinia sclerotiorum can now find it in three new disease-resistant germplasm lines dubbed "RHA 439," "RH 440" and "HA 441." Scientists with the Agricultural Research Service and North Dakota State University at Fargo and Carrington, N.D., cooperatively developed, tested and released the germplasm lines.

Sclerotinia causes two diseases in sunflower--stalk rot and head rot. During peak years, such as occurred in 1999, outbreaks of the two diseases in U.S. sunflower crops can cause $100 million in losses. Sclerotinia head rot occurs less often than stalk rot, but it's just as destructive. Sunflower heads infected with the disease can disintegrate before their seed can be harvested.

New commercial cultivars bred from the resistant sunflower lines should suffer far less damage from the fungus, according to Tom Gulya, a plant pathologist at the Sunflower Research Unit, part of ARS' Red River Valley Agricultural Research Center in Fargo.

In nursery trials there and in Carrington, the average incidence of head rot disease that the scientists observed in the three germplasm lines was 16, 33 and 8 percent, respectively, for RHA 439, RH 440 and HA 441. This compared to 58 percent for four commercial cultivars used for comparison.

Gulya and Jerry Miller, a geneticist at the Sunflower Research Unit, used conventional breeding techniques to develop the sunflower lines' improved resistance to head rot. Although the seed yields compared well with those of the commercial cultivars, the germplasm lines aren't intended for stand-alone use. Breeders seeking to develop new cultivars from them will also have to incorporate high oleic acid content and other agronomic traits that growers need.

Read more about this research in the May issue of Agricultural Research magazine.

ARS is the U.S. Department of Agriculture's chief scientific research agency.