2005 Year in Review

From the Fields - Soybean Cyst Nematode

Source: Jim Morrison, Extension Educator, Crop Systems, Rockford Extension Center, University of Illinois, Phone 815-397-7714; FAX 815-397-8620, E-mail morrison@uiuc.edu

Soybean cyst nematode (SCN) infestations are in 100 percent of all counties in Illinois. In fact, greater than 80 percent of soybean fields in the state have SCN. SCN can be present at damaging levels in a field without the obvious above ground symptoms. It’s a pest problem that simply cannot be ignored!

The key to effective SCN management is early detection. This is accomplished by soil testing and fall is an ideal time to get this task done. One set of soil cores can be used for both soil fertility and SCN testing. Logically, one would sample a corn field after harvest if soybean will be grown there in 2006. A field that has grown soybean in 2005 can be sampled as well, especially if symptoms or low yields were experienced.

The following guidelines for sampling fields for SCN were provided in a recent Iowa State University Integrated Crop Management newsletter and they are appropriate for Illinois:

- Ideally, fields should be sampled using a soil probe.
- Soil cores should be collected to a 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.
- 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.

Soil can sampled in the fall until a snowfall or until the ground freezes. Soil samples should be delivered or mailed to a laboratory soon after collecting them. Keep samples cool until mailing.

If a field has not been sampled for SCN, a cyst count (number of SCN cysts per 100 cc of soil) can be conducted. If the field has been sampled previously and resistant varieties have been grown, an egg count is the preferred test to be conducted.

Since not all resistant varieties are equally resistant, the levels of resistance found by the University of Illinois are at VIPS.

For a list of laboratories that offer SCN analysis of soil samples as well as additional information, contact your Extension office.

by  Editor, theCity1.com
November 13, 2005