VANDUSER, MO., soybean producer John Engram and his consultant, Bill Emerine with Ag One, have taken most of the guesswork out of screening varieties for soybean cyst nematode resistance. Emerine and Engram use an NG-type test through the Extension Nematology Laboratory at the University of Missouri, Columbia.
Emerine recommends using the test in fields with a history of SCN problems, where yields are going down or on fields where there is an intensive management program for increasing yields.
Engram submits a soil test to determine SCN infestation. If the test reveals moderate to high numbers, another soil sample is submitted to grow out the nematodes in a greenhouse.
An inoculum level of eggs is added to several indicator soybean lines. The lines represent eight different sources of resistance to SCN. The infected lines are grown at optimum conditions for SCN growth. After 30 days, females are removed from the roots of each seedling and counted.
The numbers are compared to a chart which shows the relative level of resistance of each indicator line to that specific SCN. The farmer can choose a variety that has the best source of resistance for his field. The Web site www.ag.uiuc.edu/~wardt/cover.htm provides a comprehensive listing of the sources of resistance for commercial soybean lines (see story about Engram's management system on Page 1 of this issue).