Four out of every five animals on earth today is a nematode so it is not surprising that agricultural fields are home to many nematode species. Fortunately, most nematodes are beneficial to crop growth and soil health because their activities help decompose crop residues and cycle nitrogen and other nutrients. Pest nematodes do not threaten yield if their numbers remain low. The key to avoiding population explosions of nematode pests is to be proactive know what the situation is and take appropriate measures when nematode numbers indicate a problem is brewing.
In 2015, the Wisconsin Soybean Marketing Board is again offering the expanded nematode testing program to include other pest nematodes in addition to soybean cyst nematode (SCN). These nematodes are less damaging to soybeans than SCN but can cause enough yield loss to warrant treatment.
"As is the case for SCN, there are no rescue treatments for nematodes so the primary purpose of this year's soil test is to plan for next year's crop," says Shawn Conley, Soybean and Wheat Extension Specialist. "Soil samples collected in corn for nematode analysis have predictive value for explaining yield if they are collected before the corn V6 growth stage. Sampling early in the season will provide information about the risk potential for the current corn crop and the next soybean crop."
Eggs of SCN persist in the soil between soybean crops so a sample can be submitted any time that is convenient. The soil test report indicates the number of eggs in the sample and is useful for selecting the right variety for the next soybean crop. Retests of fields planted with SCN-resistant varieties over multiple years shows how the nematode population is responding to variety resistance and provides an early warning should the nematode population adapt to host genetics. http://pestsurvey.wi.gov/plantdisease/pdf/soybean/2012StatusOfSoybeanCystNematodeInWisconsin.pdf
The assays used to recover nematode pests other than SCN in soil require that the nematodes are alive. So, it is important to keep the samples moist and at least room temperature cool. Collecting a sample that includes multiple cores ensures that there will be plenty of root pieces to assay. It is not necessary to include live plants in the sample. The soil test report will indicate which pest nematodes are present and at what quantities and their damage potential to soybean and corn based on the numbers recovered.
Free soil sample test kits are available now and can be requested at freescntest@mailplus.wisc.edu.
For more information on SCN testing and management practices to help reduce the losses from this pest, please contact: Shawn Conley: spconley@wisc.edu; 608-262-7975 or visit www.coolbean.info.
The Wisconsin Soybean Marketing Board (WSMB) is a grassroots, farmer-led organization that leads efforts in soybean research and the expansion of soybean market opportunities. Established in 1983 as part of a Wisconsin-mandated checkoff, the board works every day to maximize the profitability of Wisconsin's 11,000 soybean growers. It builds soybean demand, creates new uses for soybeans, and focuses on soybean disease research. The Wisconsin Soybean Association (WSA) represents soybean farmer-members to positively impact regulatory and legislative issues on a local, state and national level.3.27.2015