Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
4/7/00
Contacts:
Greg Tylka, Department of Plant pathology, (515)
294-3021
Julie Todd, Extension Communication Systems, (515)
294-2405
Spring Testing For Soybean Cyst Nematode Needed
AMES, Iowa -- Soybean cyst nematode (SCN) is a widespread and serious pest of soybeans in Iowa. A key to managing SCN is early detection of infested fields. For more than a decade, the Iowa State University (ISU) Plant Disease Clinic has analyzed soil samples for the presence of SCN. The clinic's 1999 findings indicate a decrease in sampling for SCN in Iowa.
ISU Extension Nematologist Greg Tylka said the trend of decreased sampling for SCN is disturbing because the pest's eggs can survive for as long as a decade in the soil without food. Also, unhealthy plants may not appear for many years after the nematode has been introduced into a field.
"I sense that many growers and others associated with soybean production in Iowa have become complacent concerning SCN and have forgotten about its potential for devastating damage to soybeans, particularly in drought conditions. That's unfortunate, but understandable, because Iowa has not had a year of extreme SCN damage statewide since the late 1980s," Tylka said.
With predictions of statewide drought conditions for the 2000 growing season, Tylka said it is critical that SCN infestations be identified so that resistant soybean varieties can be planted. He urged growers to test their soybean fields this spring for SCN. Sampling information can be obtained from local ISU Extension county offices or from most private soil-testing laboratories.
In 1998, the ISU Plant Disease Clinic tested 4,335 soil samples for the presence of SCN, but only 2,588 in 1999, a 40 percent decrease in one year. A survey of six private soil-testing laboratories with personnel trained by ISU to test soil samples for SCN indicates that more soil samples were sent to the private facilities for SCN analysis in 1999 than in 1998. However, the number of samples sent to private laboratories in 1999 was not enough to account for the decrease in samples being sent to ISU. Clearly, fewer fields are being tested for SCN.
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