SCN might be big surprise of 2012
You might have lost bushels of soybeans to soybean cyst nematode in the last couple of years and not even have known it, says Sam Markell, North Dakota State University Extension plant pathologist.
But you may become well aware of the damage SCN is causing if the 2012 growing season is more normal, without excessive rain or other things that clip soybean yields, he says.
Plants infested by SCN — a microscopic nematode that lives in the soil and feeds on soybean plant roots — will turn yellow early and yield 20% to 30% less than clean plants, he says. You’ll likely see SCN appear in patches in a field first.
Some plant diseases, such as brown stem rot, are worse when plants are infected with SCN.
“One of these years SCN is going to surprise people, and it won’t be a pleasant surprise,” Markell predicts.
SCN has been around for a long time in South Dakota. But it may be a surprise that SCN is already widespread in North Dakota. A survey in 2011 found it throughout the Red River Valley and most adjourning counties in the eastern part of the state. (The exception was Walsh County, but that’s probably an aberration, Markell says. There’s no reason Walsh County wouldn’t have SCN.)
SCN was first found in the U.S. in the early 1950s. By turn of the century, it had spread everywhere soybeans were being grown, except North Dakota. It was officially confirmed to be present in the state in 2003.
For years, few people have been willing to talk about SCN, Markell says. Nobody wanted to be the first to have it, and nobody wanted to admit seeing it because of the impact its presence might have on land rents and values.
“We need to start at least talking about the threat SCN poses now,” Markell says, “because SCN can be managed by planting resistant varieties and rotating to nonhost crops.”
The key is knowing which fields have SCN and how many SCN eggs are in the field. That will determine how long you should stay out of soybeans and whether you should only plant SCN-resistant varieties in the field in the future. Soil sampling in the fall is the best way to confirm the presence of SCN, Markell says.
For more information, see www.extension.iastate.edu/Publications/
This article published in the February, 2012 edition of DAKOTA FARMER.