As soybean harvest approaches across Iowa, farmers have an opportunity to check their fields for a pest that can quietly reduce yields without producing obvious symptoms.
Soybean cyst nematode, or SCN, remains one of the most damaging soybean pests, and once it becomes established in a field, it does not go away. Dylan Mangel with the University of Nebraska and the SCN Coalition says farmers can test for the pest throughout the growing season, but the period immediately following soybean harvest provides an especially good opportunity.
SCN populations are expected to be at their highest following a soybean crop, making the pest easier to detect through soil sampling. Testing also gives farmers information they can use when planning crop rotations and selecting soybean varieties for future growing seasons.
Harvest data can help farmers determine where those samples should be taken. Mangel says yield monitors can identify areas where production falls off without an obvious explanation. Farmers can then take samples from those areas and compare them with portions of the field where yields remained stronger.
Testing resources vary by state, and Mangel encourages farmers to contact their local Extension service to see what programs are available.
One reason testing is important is that SCN damage is not always easy to recognize from above-ground symptoms. A field can appear relatively normal while the nematodes feed on soybean roots and reduce the crop’s yield potential.
That means farmers may not realize SCN is responsible for lost production. Mangel says some growers could be losing 5, 7, or even 10 percent of their potential without knowing there is a problem.
Rather than waiting for severe damage to make the presence of SCN obvious, farmers can use information already being collected during harvest to identify areas worth investigating.
The SCN Coalition says taking note of unexplained yield losses, collecting soil samples following soybean harvest, and determining whether SCN is present can provide farmers with information they need to make management decisions for the next soybean crop.
