Farmers looking for any bit of good news in all of the rain-soaked suffering this spring are asking if the extreme overabundance of moisture has drowned soybean cyst nematode (SCN).

“Unfortunately, the answer is no,” says Greg Tylka, Iowa State University nematologist and lead­­er of the SCN Coalition.

Nematodes are worms that require oxygen. “Waterlogged soils may have greatly reduced levels of oxygen,” says Tylka. “But many plant-parasitic nematodes, including SCN, can survive long periods of time with little oxygen.”

In the early 1970s, scientists at the University of Arkansas conducted experiments to...