In Tennessee, many soybean fields are looking good this year, but experts say more cases of Sudden Death Syndrome are showing up which means there could be trouble below in the form of soybean cyst nematodes.

“We’re monitoring the populations that are present in the state of Tennessee and we’re finding they’re changing,” says Pat Donald, Nematologist with USDA. “What this means is the sources of resistance that have held the level of soybean cyst nematode down in commercial varieties are in some cases no longer as effective as they used to be.”

Donald, who is also an adjunct professor with the University of Tennessee Institute of Agriculture, is leading a study on soybean cyst nematodes at the West Tennessee Research and Education Center. She says the study’s findings could have a dramatic effect on the state’s soybean producers.

“What we’re finding is more and more fields are coming back with a SCN population that is able to reproduce on the most common source of resistance available on commercial varieties,” says Donald. “In the state of Tennessee, all populations we have tested are able to reproduce on the most common source of resistance in soybeans.”

Soybean cyst nematodes can be devastating to soybean crops, causing chlorosis and even plant death. Experts say soybean cyst nematodes are also an indicator of Sudden Death Syndrome. Reports estimate SCN costs U.S. soybean producers $500 million a year. Donald says another cause for concern is that many farmers are not even aware they have a potential problem on their hands.

“People are not out there looking and not checking roots and they’re not requesting soil samples,” says Donald. “The figures throughout the Midwest show you can see 30 percent yield loss without seeing any visible symptoms above ground. So a typical windshield survey will not tell if you have a problem.”

Experts say to get to the root of this problem you should literally dig to the root where the nematodes invade. And by checking fields right before harvest, when nematode populations are at their highest, you’ll be able to most accurately assess the situation and possibly prevent yield loss in the coming years.

“If producers are not monitoring and they’re using a resistant variety and the nematode level builds, they’re going to eventually see reduced yield,” says Donald. “So we are urging producers to monitor their fields now so that they know when they have a problem before they have a major yield loss.”