Like the pioneers of the Oklahoma land rush, soybean cyst nematodes are moving west and staking claim to new land.

Paulette Pierson, regional education coordinator for the SCN Coalition, believes it's actually an old claim just up for renewal.

First identified in North Carolina in 1954, SCN spread west and north, eventually reaching the heart of the nation's Soybean Belt. Recent diagnoses in parts of the Midwest are thought by many to be a continuation of the pest's migration.

But Pierson figures most of the movement took place years ago.

"The spread or introduction of SCN occurred some time in the past," she states. "I believe it's just now being identified."

Very high SCN populations are being found in areas where the pest previously had never been identified. The high numbers indicate SCN has been there for years, she says.

For example, counts of over a quarter million eggs in 200 cc of soil were found last year in a previously "SCN-free" county in Ohio.

"Those are extremely high counts if you consider 250 eggs in the same volume of soil can cause damage to SCN-susceptible soybeans," says Pierson.

She says SCN is probably present in more counties than the map below indicates.

In fact, it likely infests most soybean-growing counties.

"Growers really haven't been sampling. Where it hasn't been identified, it probably hasn't been looked for." The fact that SCN probably infests most fields emphasizes the need for growers to identify the problem and adopt a control program. That program should include periodic soil testing to monitor nematode populations.

"SCN can be managed," she says. "But you can't say I'm going to put a Band-Aid on it and just plant resistant varieties. You need to know if SCN numbers are increasing or decreasing with your management strategy."