Soybean Cyst Nematode (SCN) is by far the most serious pest, causing over a billion dollars in soybean yield losses every year. It was first found on U.S. shores in 1954 in North Carolina and has spread from there.
SCN is a microscopic roundworm that appears in all major soybean production areas.
It’s sneaky, too. SCN causes no specific symptoms and its effects are often undramatic, so growers may be unaware they have a problem until a severe infestation develops. The yield hit due to SCN can soar over 50%.
We do have tools to fight back. By understanding the life cycle of SCN, performing routine soil sampling and using proper crop management, we can reduce the incidence of this noxious pest.
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.
In 2016, the WSMB is again offering the expanded nematode testing program to include other pest nematodes in addition to SCN. These nematodes are less damaging to soybean 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. 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.
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
To combat this scourge and encourage soil sampling, Wisconsin growers are eligible to have soil samples anaylzed for soybean cyst nematodes and other plant parasitic nematodes at no charge. The testing fees are underwritten through a grant from the Wisconsin Soybean Marketing Board.
To request a free soil sampling kit, send an email to email@example.com