Cooperative Extension Service, Kansas State University, Manhattan, Kansas
Figure 1. Typical stunting of corn caused by the sting nematode.
Figure 2. Greatly enlarged adult female sting nematode showing slender, elongated stylet (center) used for reaching deep inside root tissue.
In general, symptoms consist of greatly reduced root systems with short, stubby roots having dark, shrunken lesions, particularly at the tips. If the root tip is destroyed, new roots may be produced above the damaged area, resulting in a highly-branched appearance (Figure 3). Plants which are not severely damaged by the initial feeding may recover and produce near-normal yields under optimum growing conditions.
|corn||pearl millet||morning glory||bentgrass|
|oats||ladino clover||wild carrot||peach|
Field symptoms usually consist of severe stunting, wilting, yellowing, and sometimes death. Infested areas consist of spots that vary in size and shape, but the boundary between diseased and healthy plants usually is fairly well defined (Figure 1).
Other field problems can mimic sting nematode symptoms. These include damage from two other nematodes, the stubby-root nematode (Trichodorus and Paratrichodorus spp.) and the stunt nematode (Tylenchorhynchus spp.). While both of these nematodes will cause root pruning, neither produces the root lesions characteristic of the sting nematode. Dinitroaniline herbicides such as trifluralin can also produce a root pruning similar to sting nematode damage (Figure 4), but, again, root lesions will not be present.
Due to the severity of the damage caused by the sting nematode (especially to corn), detection of the nematode's presence in a field is more critical than the determination of actual numbers. Any number is a potential threat to crop production.
Complete guidelines for collecting soil samples for nematode assay are available at local Cooperative Extension Service offices.
While wheat is an excellent host for the sting nematode, the crop can sometimes be grown successfully in infested fields by taking advantage of the natural population cycle of the nematode. In the fall when wheat is planted, nematode numbers in the upper soil profile are generally at their lowest point. This should always be confirmed by a nematode assay of the field.
By the time nematode populations increase in the spring, the wheat has made enough growth to withstand most of the damage. Because the nematode reproduces extremely well on wheat, planting a susceptible crop following wheat, especially if it is double-cropped, could lead to significant yield losses.
The most effective control currently available for the sting nematode is an at-planting application of a labelled nematicide. Impressive yield increases have been obtained with nematicide applications to sting nematode-infested corn fields in Kansas (Table 3).
Figure 3. Roots of corn (left) and soybean (right) with severely pruned roots caused by the sting nematode.
|Number of nematodes /100 cm3 soil|
|Nematicide*||Rate lb/A||%Reduction in nematode Population||Yield Increase||Chemical Cost/A Bu/A|
|Counter 15G||6.67||79||20||$ 11.00|
|Counter 15G||13.33||85||24||$ 21.00|
|Furadan 15G||6.67||34||2||$ 9.00|
|Furadan 15G||13.33||48||9||$ 18.00|
Figure 4. Comparison of root damage to corn from the sting nematode (left) and trifluralin (right).
Contact your local county Cooperative Extension Agent for current nematicides and rates recommended in Kansas.
L-817 May 1990
Issued in furtherance of Cooperative Extension Work, acts of May 8 and June 30, 1914, as amended. Kansas State University, County Extension Councils, and United States Department of Agriculture Cooperating, Walter R. Woods, Director. All educational programs and materials available without discrimination on the basis of race, color, national origin, sex age, or handicap. 5-90- 4M
File Code: Plant Pathology 1-3