August 10, 2007

Silent robber can cause soybean losses

Each year soybean cyst nematodes (SCN) cause millions of dollars of damage to Nebraska's soybean crop, often without producers being aware of their activity. SCN can cut soybean yields and reduce profitability while seemingly being invisible.

UNL Extension with support from the Nebraska Soybean Board, will sponsor four field days this August to alert soybean producers and ag professionals to potential damage and help them learn to identify and manage SCN to minimize impact on yields.

If the current yield losses from SCN in Nebraska were being caused by soybean rust, it would be the lead ag story across the state. While soybean rust has received much attention, SCN has earned the title of "The Silent Yield Robber." Yield losses of 20-30% have been documented in the state with no above ground symptoms on the plant.

If SCN caused holes, lesions, spots or other plant abnormalities, it would be much easier to know when to test for and manage it; however, infested plants usually look healthy. The first indication of a problem is soybean yields that have leveled off or even started to drop while corn or other crop yields in the same field continue to improve.

Originally identified in counties bordering the Missouri River, SCN has been identified in 41 counties in eastern and central Nebraska as far west as Boyd, Valley Buffalo, and Kearney counties. As soybean production has moved across the state, so has the distribution of soybean cyst nematodes.

At four SCN-infested field day sites in 2006, SCN-resistant varieties outyielded susceptible varieties by an average of seven bushels. These infested sites had low to moderate levels of infestation. There was no difference in yield between the same susceptible and resistant varieties at a site which was not infested with SCN.

The Soybean Cyst Nematode Field Days are presented by UNL Extension with support from the Nebraska Soybean Board. For more information, contact your local UNL Extension office.

John Wilson
Extension Educator, Burt County
Loren Giesler
Extension Plant Pathologist, Lincoln