There is still time this spring to check fields for the presence of soybean cyst nematode (SCN) before planting starts. This nematode is widespread throughout much of Iowa. However, soybean cyst nemadote infestations can go unnoticed because obvious aboveground symptoms may not be visible for many years after the introduction of the pest into the field. Early detection of soybean cyst nemadote infestations, when population densities (numbers) are still low, is very important. It is much easier to keep low population densities of soybean cyst nemadote in check than to try to decrease high population densities. If soybean cyst nemadote infestations are discovered in fields where soybean is to be grown in 2004, growers might be able to change their variety selection and plant an SCN-resistant soybean.

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Sampling for soybean cyst nematode.

The only way to check fields for soybean cyst nemadote before planting is to collect soil samples and have the samples analyzed for the presence of soybean cyst nemadote. The following are guidelines for sampling fields for soybean cyst nemadote:

• sample fields using a soil probe
• collect soil cores to a total depth of 6 to 8 inches
• collect soil cores from 15 to 20 places in a sampling area
• collect a separate set of soil cores for each 20 acres or so
• combine and mix soil cores, and fill a sample bag with one cup or more of soil
• label the outside of each sample bag with a permanent marker

Many private soil fertility laboratories offer soybean cyst nemadote testing of soil samples, as does the Iowa State University Plant Disease Clinic. The mailing address of the clinic is Plant Disease Clinic, Department of Plant Pathology, 323 Bessey Hall, Iowa State University, Ames IA 50011-1020. The current fee for soybean cyst nemadote analysis is $15 per sample.

Numerous Iowa State University Extension publications on soybean cyst nemadote, including a list of SCN-resistant soybean varieties, can be obtained through any Iowa State University Extension county office or here.