Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
1/24/00
Contacts:
Greg Tylka, Extension Plant Pathology, (515) 294-3021,
gltylka@iastate.edu
Elaine Edwards, Extension Communication Systems, (515)
294-5168, eedwards@iastate.edu
Resistant Soybean Varieties Provide Benefits Even at Low Soybean Cyst Nematode Densities
AMES, Iowa -- Soybean cyst nematode (SCN) is a widespread and devastating pest of soybeans throughout Iowa. As many as three-fourths of Iowa fields are infested with the nematode.
One of the most effective means of managing SCN is by growing SCN-resistant soybean varieties. Each year, the Iowa State University (ISU) Department of Plant Pathology evaluates the performance of SCN-resistant soybean varieties at locations throughout the state.
"In 1999, the experiments conducted in the northern Iowa location of the variety trial (Kanawha, Iowa) provided some unexpected and valuable results," said Greg Tylka, Iowa State University Extension nematologist.
"At the northern Iowa experimental location in 1999, the number of SCN eggs at the beginning of the growing season averaged between 200 and 400 eggs per 100 cc soil. That level is barely above the detection level for soil sampling for SCN," Tylka said. "However, at the end of the season, the SCN-resistant soybean varieties yielded on average 2 to 7 bushels per acre more than the susceptible varieties in the experiment."
Also, end-of-season SCN numbers were two- to five-times higher in the plots where susceptible varieties were grown than where SCN-resistant varieties were grown.
"These results illustrate why Iowa State University staff recommend that growers plant SCN-resistant soybean varieties once an infestation of the nematode is discovered, even if the nematode numbers are very low," Tylka said.
Single copies of a report of the results of the 1999 ISU SCN-resistant soybean variety trials (publication IPM-52) can be obtained for free by contacting the ISU Extension Distribution at (515) 294-5247. Results also are available on the Internet at http://www.scnfacts.org by selecting "ISU Extension publications," then "1999" under "Evaluation of SCN-resistant soybean varieties."
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