West Virginia Department of Agriculture
Plant Industries Division
Market Bulletin Article
January 2008 Issue
Norman L. Dart
Agricultural Plant Pathologist
Over the past few years plant parasitic cyst nematodes have received a lot of attention in agricultural circles. The 2006 detection of pale cyst nematode (Globodera pallida) in soil from an eastern Idaho potato grading facility started this recent surge of attention. The find caused Canada, Mexico and Korea to temporarily ban the import of potatoes from Idaho while Japan stopped importing potatoes from the entire United States. Only after intensive surveys were conducted throughout Idaho showing infestations were localized did most countries lift bans on U.S. potatoes.
The Idaho pale cyst nematode find was followed with the July, 2007 report of a new species of cyst nematode found on stunted corn in Tennessee. University of Missouri plant pathologists made the discovery and confirmed the species was genetically different from Heterodera zeae, a corn cyst nematode known to parts of Maryland and Cumberland county Virginia since 1981.
Fortunately, the pale cyst nematode seems to have been detected and controlled before it was able to cause devastating yield losses as it has throughout Europe. Likewise, the new nematode species found on corn is not thought to be widespread. This doesn’t mean these threats shouldn’t be taken seriously. Cyst nematodes have a history of devastating crops around the world and some species currently cause significant damage to crops in the US. The golden cyst nematode (Heterodera rostochiensis), for example, was first discovered in Germany by Julius Kuhn in 1881 during a campaign against the sugar beet nematode. At the time the newly described species was considered a curiosity. By 1913 populations of the exotic pathogen (a native of Peru) built up and devastated potato yields in Germany. Golden cyst nematode eventually spread throughout Europe and parts of India and Africa. In 1941 the golden nematode was discovered in Long Island, NY potato fields. Another example includes the soybean cyst nematode (Heterodera glycines), which was first introduced to the US in the early 1950s. Since its introduction it has spread throughout the southern and midwestern US where it can cause 15-30% yield loss without causing visible symptoms.
Although minimal survey data is available, West Virginia is thought to be free of the more damaging cyst nematode species (e.g. soybean cyst nematode). This is good news since cysts produced by these nematodes allow them to survive several years in the soil. Once cyst nematodes are introduced to a field growers must rely on rotating non-host crops (sometimes for several years) to control nematode populations and/or growing resistant cultivars if available. The preferred strategy is to be proactive and keep cyst nematodes out of your fields to begin with. Inadvertently introducing cysts in soil and organic debris stuck to equipment, nursery stock or work boots is believed to be a common route of infestation. The key to protecting yourself is to practice sanitation in all aspects of your farming operations. For example, when buying used farm equipment make sure to wash off all soil and organic debris before using the equipment. If the equipment is from a neighboring state or region where exotic cyst nematodes are already introduced consider finding another source of equipment.
In West Virginia, some of the commodities at risk to cyst nematodes include corn, soybeans, wheat, oats and potatoes. If you grow any of these crops and notice patches of stunted or yellowing plants (not likely caused by spring floods), or you have noticed reduction in yield over a several year period you should get your soil tested for nematodes. To arrange for a site visit by Plant Industries call Norm Dart at (304)558-2212. Plant Industries is also looking for cooperators who would like to have their crop soil tested as part of a state wide nematode survey the Department of Agriculture will be conducting during the 2009 growing season.
Featured Links: Nematodes of agronomic and regulatory concern
Soybean Cyst Nematode: http://www.planthealth.info/scnguide/
Corn Cyst Nematode: http://www.ipm.iastate.edu/ipm/icm/2007/7-30/nematode.html
Pale Potato Cyst Nematode: http://plpnemweb.ucdavis.edu/nemaplex/taxadata/G053S1.HTM
Golden Potato Cyst Nematode: http://programs.cphst.org/pcn/files/GN%20Factsheet.pdf
Collecting and preserving nematodes: http://www.spc.int/pps/SAFRINET/nem-scr.pdf