Soybean varieties with resistance traits for soybean cyst nematode or root-knot nematode go a long way to help manage the yield-robbing pest, but growers shouldn’t let their guard down.
Two additional forces are at play:
- Nematodes are adapting to resistance traits
- Nematode and nematode pressure is increasing across species
While soybean cyst nematode (SCN) is more prevalent in the major soybean producing states in the Midwest, producers in the South still have the opportunity to sidestep an emerging problem by including resistance management in their nematode program.
The SCN Coalition offers four tips for managing nematodes, particularly soybean cyst.
- Test your field for nematodes
- Rotate resistant varieties
- Rotate to non-host crops
- Consider using a nematode protectant seed treatment
Test your field for nematodes.
For the most accurate results, Auburn University Extension Plant Pathologist Ed Sikora recommends sampling between late August and late October. Generally, Sikora said, fields should be sampled every two to three years, unless problem areas develop. Once a grower knows which nematodes are present and at what levels, a decision can be made on whether to plant resistant varieties.
“Using SCN-resistant soybean varieties can be very effective for managing the pathogen,” Sikora said. “The most important characteristic of SCN-resistant varieties is yield potential in SCN-infested fields.”
Root-knot nematode pressure, however, is more difficult to manage with resistant varieties, Sikora said. “Several soybean cultivars have claimed root-knot resistance,” he said. “However, some appear to be losing this resistance in certain areas, particularly in South Alabama. Growers should, therefore, carefully observe the performance of these root-knot resistant cultivars if they are grown in fields with severe root-knot infestations.”
Rotate to non-host crops
Rotating to non-host crops effectively manages both SCN and root-knot nematode.
“Several non-host crops – such as corn, cotton, peanuts and grain sorghum – can be used in a rotation system to control SCN. In fields with moderate to high cyst populations, growers should follow a 3- or 4-year rotation using non-host crops and resistant cultivars,” Sikora said. “Root-knot species have a wide host range, but some non-host crops can be used effectively in a crop rotation scheme to reduce populations. Grain sorghum, coastal Bermuda and some cultivars of pearl millet are considered good rotation crops.”
Cotton also is an effective rotation crop to control root-knot nematode when a grower knows which races are present in a field. “Cotton, although susceptible to Southern root-knot races 3 and 4, is an effective rotation crop in fields with Southern root-knot races 1 and 2, or in fields with peanut root-knot.”
Consider using a nematode protectant seed treatment
Yield and price opportunity will influence whether nematicide application should be part of a grower’s management plan.
“Nematicides applied to seed or used in-furrow can reduce early-season root infection by nematodes, but do not provide season-long control and may not be economical,” Sikora said. “Nematicides can be effective in controlling SCN populations in infested fields but will not replace the use of resistant varieties and crop rotation as primary management practices for nematode infestations.”
Overall, Sikora said, the key is to be aware of nematode pressure and manage according to field impact.
“SCN is not a new problem. But, SCN is often overlooked because of other disease and insect pests that damage soybeans in the state,” Sikora said. “Yield reduction from SCN will vary from field to field based on the nematode population present.”
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