Soybean cyst nematode common in Elkhart County fields
Posted: 11/30/2012 at 1:15 am
Soybean cyst nematode is a common pest of soybeans in Elkhart County. According to Purdue nematode specialists, about 45 percent of Indiana fields are affected by SCN.
Above-ground symptoms of SCN are generally more noticeable when soybean plants are under stress from such conditions as drought, low fertility or compaction. Yellowed patches, often mimicking other problems such as drought injury or nutrient deficiency, occur in uneven patches in the field. Infected plants have poorly developed roots and very few Rhizobium nodules.
Early in the growing season (six weeks after planting), close examination of the roots may also reveal small, white to yellow spheres (bodies of female nematodes) attached to the root surface. These females are not much bigger than grains of coarse sugar, and should not be confused with the much larger Rhizobium nodules
Crop rotation is a good way to fight this pest. The rotational crop and the weeds that are present are important considerations. Corn, alfalfa, wheat, sorghum and oats are among the crops that are not hosts to SCN. Sweet clover, red clover, alsike clover and hairy vetch can serve as an alternative host to SCN, as can several weed species, including, purple deadnettle, henbit, common mullen, wild mustard, common chickweed and pokeweed.
Variety resistance is another way to fight SCN. Used with crop rotation, SCN can be managed effectively. Iowa reports there are literally hundreds of variety with SCN resistant genetics, about 96 percent of which are using the PI88788 gene. These cultivars donít necessarily react the same way toward an SCN population since there so many races of the nematode in area fields. Soybean cultivars with Peking or PI437654 (CystXģ, Hartwig) source of resistance should be used if your SCN population can overcome the PI88788 resistance. Purdue recommends growers do a race or an HG type test of their SCN population every 10 years or if they have never done so in the past.
For information about how to manage soybean cyst nematode, you can contact your Extension office or visit extension.entm.purdue.edu/nematology/index.html.
Jeff Burbrink is an Extension educator in agriculture and natural resources. Write to him at 17746 E. C.R. 34, Goshen, IN 46528; call 533-0554; or fax 533-0254.