By Greg Tylka, Extension Plant Pathologist
A simple but potentially valuable spring task to consider is sampling fields for the soybean cyst nematode (SCN). And since we are heading into the cropping season, it makes sense that attention be given to those fields in which soybeans will be grown in 2016.
Have those fields ever been sampled for SCN? If not, now would be a great time.
If the fields were sampled in the past, how long has it been?
In fields known to be infested with SCN, what are the population densities? Is your management plan keeping your SCN numbers in check?
The answers to these questions can be worth $100 or more per acre in avoidable soybean yield loss.
Spring Sample Guidelines
Multiple soil cores (20 cores from every 20 acres or so) should be collected from the upper eight inches of soil.
The more soil cores collected and the smaller the area sampled, the more accurate the results will be.
Do not collect samples when the fields are muddy.
One approach to sampling fields in which SCN has not been discovered is to collect soil cores from high-risk areas where SCN may be first found. These areas include high pH spots, low spots, and near fence lines and other places where soil from other fields may have been introduced (see figure below).
- Samples can be sent to several private soil-testing labs in Iowa or surrounding states or to the Iowa State University Plant and Insect Diagnostic Clinic, room 327 Bessey Hall, 2200 Osborn Drive, Ames, IA 50011. The SCN sample submission form for the ISU Clinic is available online here.
Managing SCN is best accomplished by using an integrated approach of growing a diversity of SCN-resistant soybean varieties in rotation with the nonhost crop corn and using nematode-protectant seed treatments when soybeans are grown.
There are numerous articles and other resources available about the availability and effectiveness of SCN-resistant soybean varieties and seed treatments on the ISU Integrated Crop Management News site. These resources can be found by searching for “SCN” in the search box at the top of this page.
More information about the biology and management of SCN is available at www.soybeancyst.info andsoybeanresearchinfo.com. Iowa State University’s management recommendations for SCN are available online in a downloadable format, Soybean Cyst Nematode (SCN) Management Recommendations, IPM 63.