Fall is the time to check for nematode
By Jason Jenkins, University of Missouri information specialist

Soybean producers who experienced unexplained yield losses this season should test their fields for soybean cyst nematode this fall.

“Producers will blame lost yield on everything except SCN because they’re planting resistant varieties,” said Bob Heinz, coordinator of the MU Nematology Laboratory. “However, research is revealing that those varieties may no longer be resistant.”

Heinz referred to a 2005 University of Illinois survey that determined 74 percent of SCN populations in Illinois can attack most resistant soybean varieties. A survey in Missouri would likely produce a similar result, he said.

“More than 90 percent of all SCN-resistant beans planted in Missouri derive their resistance from the same source,” Heinz said. “By only using one source of resistance, you’re just asking for trouble. Producers think they’re growing resistant beans, but really they’re developing a population of nematodes that may grow well on their resistant lines.”

Fall is the best time to sample fields for an egg count.

“The crop is off the field and SCN populations are at their highest levels,” said Heinz. “Even if farmers don’t want to sample all their fields, they should at least sample that one field they have that doesn’t yield like it should. A field will have hot spots, so grab a five-gallon bucket and start walking the field in a zigzag pattern, taking a plug of soil about every 50 to 100 paces. Mix the sample well and send about a pint of soil in for testing.”

Should an egg count test reveal high levels of SCN, Heinz said an HG Type race test may be necessary to determine the race of SCN in the field.

For more information on sampling techniques, fees and to download sample submission forms, go online to http://soilplantlab.missouri.edu.