Research

Determining the impact of multiple pests on soybean yield and grain composition

Results of preliminary research from 2003 to 2007 indicated that amino acid and lipid composition of soybean leaf tissues and grain can be affected by soybean aphid, SCN, and brown stem rot. Changes in lipid and amino acid composition are particularly important in production of soybeans that produce specialty grains for which a premium is obtained only when grain composition is within contracted levels (example: low linolenic soybeans, high oleic soybeans).

Distribution of SCN in Iowa and occurrence of HG types

SCN was first discovered in Iowa in Winnebago County, in extreme north central Iowa, in 1978. Currently, the nematode is known to exist in 97 of 99 Iowa counties (all except Allamakee and Ida Counties). A random survey of Iowa was conducted in 1995-1996 to better define the distribution of SCN in the state. SCN was found in 74% of Iowa fields sampled in that survey. SCN was found much less frequently in no-till fields than in tilled fields sampled in the survey.

Field evaluation of SCN management products

Each year, one or more foliar-, seed-, or soil-applied products are advertised for use in managing SCN. Growers and agribusinesses in Iowa turn to Iowa State University for an unbiased evaluation of the effect of these products on SCN populations and soybean yield.

Field evaluation of SCN-resistant soybean varieties

An effective and affordable way to manage SCN is to grow resistant soybean varieties. SCN-resistant soybean varieties suppress SCN reproduction, reducing the yield loss caused by damage from nematode feeding. SCN resistance preserves the yield of soybean varieties growing in SCN-infested fields.

Studies of the interactions of SCN with brown stem rot of soybean

Iowa fields are commonly infested with both SCN and brown stem rot (BSR). In the early 1990s, researchers observed that BSR-resistant soybean varieties had much greater than expected levels of BSR disease in fields infested with SCN than in those without SCN.

Studies of the interactions of SCN with the soybean aphid

The soybean aphid, Aphis glycines, was first discovered feeding on soybeans in Iowa and other Midwestern states in 2000. Since then, it has spread throughout the state and region. Currently, soybean aphids are found in every county in Iowa and the insect has become a serious yield-reducing pest of soybeans in the state.