Though there are more than 40 species of nematodes have been reported on corn there is little information on the damage caused by corn nematodes in Arkansas. Some of the most common corn nematodes include; root-knot, lesion, lance, spiral, stunt, dagger, sting, and stubby root, which have been detected on corn in the state, but not always at a damaging population threshold.
Symptoms: Symptoms vary with nematode species, population density, soil type and soil moisture. Foliar symptoms consist of stunting, chlorosis, and wilting (Fig. 1). Root symptoms include necrotic lesions, abnormal root growth, and stubby roots (Fig. 2). In contrast with dicotyledonous row crops like cotton and soybean, root-knot nematodes seldom cause severe galling on infected corn roots.
Management: Cultural practices that include crop rotation with non-host or less susceptible host, and prevention of soil compaction, which restricts downward root growth, are often good nematode management practices. Many corn hybrids are excellent hosts for southern root-knot nematode (RKN), Meloidogyne incognita, and should not be used as a non-host rotation crop when attempting to manage RKN population densities in other crops such as cotton or soybean. Alternately, the reniform nematode, Rotylenchulus reniformis, and soybean cyst nematode, Heterodera glycines, do not appear to attack corn. Therefore, using corn in rotation with either soybean or cotton where these nematodes are present will lower nematode populations.
A few fumigant and granular non-fumigant nematicides are available for managing nematodes in corn although as a general rule, they should only be considered when nematode pressure is severe. Under more moderate levels of nematode pressure, seed applied nematicides are recommended. See MP 154 for current recommendations for nematicides use on corn in Arkansas.
Note: A nematode problem is rarely detected based on foliar symptoms therefore if nematodes are suspected a soil sample should be collected in the fall, shortly after harvest, and sent through the local county agent to the Cooperative Extension Service, Nematode Assay Laboratory for assessment. There is a small fee for this service but the correct diagnosis can greatly help plan future rotations.
Figure 1. Stunted and yellow corn in a commercial field
caused by a high population density of stubby root nematode.
Figure 2. Root damage caused by stubby root nematode.