DES MOINES, Iowa - Corn nematodes can be overlooked as a cause of yield-loss in corn, say experts at Pioneer Hi-Bred, a DuPont business.
Growers are seeing corn nematodes as an increasing problem in their fields. One reason is simply greater awareness of corn nematodes. This has been driven by improvements in testing methods which has increased the ability to detect infestations, thus recording higher numbers of incidents. Changes in production practices are also contributing factors.
"Common practices among growers may cause increases in corn nematodes," says Mark Jeschke, Pioneer agronomy research manager. These include reduced tillage and planting corn following corn, which are known to favor some nematode species. "In addition, many older corn rootworm insecticides also provided some level of nematode control, whereas newer insecticides and Bt traits do not," Jeschke says.
Identifying corn nematode problems can be tricky. Their small size and nondistinctive damage symptoms often allow them to go undetected.
"Their symptoms resemble those of common stress factors such as drought, nutrient deficiencies or soil compaction," Jeschke says. "Root symptoms can include pruning, proliferation of fibrous roots, thickening or swelling of the smaller roots and mild to severe discoloration. However, the only way to confirm symptoms are being caused by nematodes is to submit a sample of soil and root tissue for testing to a local lab."
There are more than 50 species of nematodes known to feed on corn in the U.S. While many of these species typically are specific to sandy soils, including parts of the Midwest and the coastal plains of North and South Carolina, Jeschke stresses that no field is immune to the potential for nematode damage.
"Nematodes are such a complex problem," says Jeschke. "There are several different types that feed on corn. Even within a particular type, there can be many different species with different behavioral characteristics."
Cultural practices such as crop rotation may be effective at controlling species that selectively feed on corn, but ineffective against species that feed on other crops.
Nematode populations are highly variable even within a single field. If you find damaging levels of corn nematodes, consider implementing control measures such as crop rotation, sanitation of equipment or use of nematicides.
Pioneer Premium Seed Treatment choices for added protection against corn nematodes include Poncho®1250 + VOTiVOTM. This combination provides protection of corn roots from nematodes as well as root-feeding insects.
To prevent spreading the nematodes into uninfested fields, clean equipment with high pressure water or steam, removing all soil particles, before moving to the uninfested area, Jeschke suggests. "If possible, conduct field operations in the infested areas last," he says.
"Because nematodes cannot be eliminated once they are established in a field, prevention is a critical management strategy," Jeschke says.