Submitted to: Midwest Soybean Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: May 21, 1998
Publication Date: N/A
Technical Abstract: Sclerotinia sclerotiorum, which causes Sclerotinia stem rot (SSR) of soybeans, occurs in Illinois, Indiana, Iowa, Michigan, Minnesota, North Dakota, Ohio, and Wisconsin. The incidence and severity of the disease throughout Illinois is not known, but in 1996, 30 out of 68 fields surveyed in Iroquois county had SSR. The fungus also was found in seed lots from the 1996 harvest as sclerotia were obtained from 81 lots grown in 21 Illinois counties. Eight of these seed lots had at least some infected seeds. In a yield loss study in that same year it was shown that yields averaged over five cultivars were reduced by about 4% for every 10% increase in disease incidence with the most severe case reducing yields by about 66%. From these and other reports, it is evident that SSR is an economic threat to soybean production in the northern soybean growing region of the U.S. There is a shift towards growing cultivars that at least carry partial resistance to the fungus and at the same time, more sources of resistance are being found in plant introductions. The transfer of these new sources of resistance to commercial cultivars may be the best approach to a successful disease management program.