Soybean Cyst Nematode Management Research (Part 2)

By Dusty Sonnenberg, CCA, Field Leader, a project of the Ohio Soybean Council and Soybean Check-off

Soybean Cyst Nematode (SCN) is the leading yield robber of soybeans in Ohio and across the nation. The challenge to SCN detection is that there are no above ground symptoms. “When we do our research, we always have different varieties and sources of resistance, and we go and we measure anything we can from these plants; height, branching, intensity of the color of the foliage,” said Lopez-Nicora. “We absolutely do not see any above ground symptomology when we have SCN. The nematode is reducing yield without any above ground symptoms.”

Lopez-Nicora reminds farmers to ask themselves if they know if they have SCN. “If the answer is no, then they should sample their fields for SCN to know if they have it or not. They should try to answer that question with data,” said Lopez-Nicora. “Ohio soybean farmers can submit up to two sample free of charge to The Ohio State University for analysis thanks to funding from the Ohio Soybean Council and supporting the mission of the SCN Coalition.”

It is easy to assume that stressed plants and lower yields are due to something other than SCN. “When farmers scout fields, they may see symptoms that concern them, such as marginal chlorosis in some of the foliage. It is often associated with a potassium deficiency in the soil. Typically they will pull a soil sample and send it to the lab for analysis and address the results the following year by adding potassium. The next year, plants should look healthy, but they may still lose yield due to SCN,” said Lopez-Nicora. “When farmers pull those samples, they can also take some  and mix them together and send in a subsample to the nematology lab to be analyzed for SCN. They may address the potassium issue, but the nematode population will continue to increase if there is SCN present. If you have SCN present, that could be the reason why the nutrient deficiency symptoms were more severe.”

Similarly, if a field has areas of Sudden Death Syndrome (SDS), that can be a good indicator of a good place to sample for SCN. “We know that there is an interaction in the presence of the nematode and the symptomology that the fungus Fusarium virguliforme and other species that cause SDS,” said Lopez-Nicora.

In a trial conducted by Lopez-Nicora in Northern Ohio, testing both of the common SCN resistances PI 88788 and Peking, observations showed that varieties with PI 88788 allowed for the reproduction of a nematode at the end of the season. Those varieties with Peking (the source of resistance which they knew that the population of the nematode cannot reproduce on) had on average a reproduction factor below 1. “Just by selecting the source of resistance that matches with the SCN population that is in the field really helps decrease the level of SCN at the end of the season,” said Lopez-Nicora.

The final takeaway is simple. “Sample to know if there is SCN present. If it is present, then find out the number of eggs per 100 cc of soil, or how much there is. If the number is high enough and there is a yield reduction, then find out what the specific population is so you can choose the correct source of resistance,” said Lopez-Nicora.