Managing nematode pests in Midsouth soybeans

Authors: Donald, Patricia; Stetina, Salliana - Sally

Submitted to: World Wide Web
Publication Type: Popular Publication
Publication Acceptance Date: 7/8/2011
Publication Date: 7/10/2011
Citation: Donald, P.A., Stetina, S.R. 2011. Managing nematode pests in Midsouth soybeans. World Wide Web. http://mssoy.org/wp-content/uploads/2012/01/NEMATODE-WHITE-PAPER-MAR-2012.pdf.

Interpretive Summary:

Technical Abstract: Soybean producers must contend with nematode pests, several species of which may inhabit a single field. Significant yield losses caused by soybean cyst (Heterodera glycines), southern root-knot (Meloidogyne incognita), reniform (Rotylenchulus reniformis) and other nematodes were estimated at 2.6% (over 19 million bushels) across the southern U.S. in 2009. Soybean cyst, southern root-knot, and reniform nematodes feed on soybean roots. Populations can build up rapidly in the soil, because females of all three types of nematodes produce large numbers of eggs in a relatively short period of time. Root damage caused by the nematodes as they feed results in aboveground symptoms such as stunting and yellowing of the foliage. Roots may be discolored and stunted, and roots infected by southern root-knot nematodes may have swellings or galls. Roots infected with soybean cyst or southern root-knot nematodes may have fewer nodules, which further limits plant growth and yield by reducing the plant’s access to nitrogen. Southern root-knot nematodes tend to be associated with sandy soils, where the combination of root damage and the reduced water-holding capacity of the soil can result in wilting of infected plants during the heat of the day. Soybean cyst and reniform nematodes are found in a wide range of soil types, including those with high silt and clay content. Research to determine the damage potential of nematodes and to establish action thresholds for control is lacking in many southern states. The data that exist are generally outdated, developed 25-30 years ago when cropping patterns, farming practices, and varieties were very different than they are today. Moreover, thresholds have never been well established for recent “newcomers” to the soybean arena including the reniform nematode. Growers must determine which nematode or nematodes are present to make appropriate nematode management decisions. Accurate identification of the nematode species and population levels present in a field requires that soil samples be collected and sent to a diagnostic lab for evaluation. If test results indicate that these species are not present in a field, care should be taken to prevent their introduction. Nematodes can be moved in soil, so clean all equipment before it enters the field. Work fields that are not infested before moving equipment to other fields where nematodes are known to exist. Established nematode populations are very difficult to eliminate, so the management goal for infested fields is to keep the nematode population as low as possible. Crop production practices that provide adequate nutrients and water and minimize stress due to insects, weeds, and diseases will help the plants withstand some nematode feeding damage. Nematicides applied to seed or used in-furrow can reduce early-season root infection, but do not provide season-long control.