By: Stephanie Karhoff
A female soybean cyst nematode, stained with a bright pink stain, has set up her feeding site within the soybean root. Her body will fill with eggs and become a bright white cyst visible on the soybean root. Photo: OSU Extension.
Soybean cyst nematode (SCN), Heterodera glycines, is a small roundworm that parasitizes soybean roots, stealing vital nutrients from the plant. Even if you are not seeing above-ground symptoms, SCN is likely still reducing your yield. To make matters worse, certain SCN populations are now becoming “resistant to the resistance.” In other words, a portion of the nematodes now have the capability of feeding and reproducing on soybean varieties previously thought to be resistant. The main reason for this, is that more than 95% of all SCN-resistant varieties for the past two decades included resistance gene(s) from the same breeding line, Plant Introduction (PI) 88788. Just like herbicide-resistant weeds, relying on the same SCN resistance source for the past 20 years has led to SCN populations adapting to, and overpowering the resistance.
Knowing the number of SCN present in your field(s), and what percent has adapted to previously deployed resistance is the first step to managing this pest. Ohio Soybean Council, along with the SCN Coalition and OSU Extension, are currently accepting soil samples for SCN testing. There is no cost, and all data will be kept confidential. Williams County growers may call the OSU Ext. Office at 419-636-5608 with field location (either nearest road intersection or GPS) and contact information to have their fields sampled. If you are sampling on your own, mix 15-20 cores taken at 6-8″ soil depth near soybean roots, keep samples cool, and bring to 1425 E. High St., Bryan. For more sampling instructions, click here.
More resources:
The SCN Coalition. www.thescncoalition.com
Soybean Cyst Nematode in Ohio. https://u.osu.edu/ohscn/