Bertha armyworm populations can be manipulated to reduce crop loss. Methods include planting alternative crops, effective weed control, early swathing and fall cultivation. Fall cultivation can kill many bertha armyworm pupae by mechanical damage. Tillage can also reduce the amount of snow trapped on a field by removing or flattening stubble and exposing pupae to sub-zero temperatures over the winter. This practice may be effective for individual fields but is not likely to be effective unless it is adopted by all producers in an area.
Adult moths are strong flyers and can easily move to adjacent fields.
Fall cultivation should not be used on light-textured soils susceptible to erosion. Effective control of weeds such as lamb's quarters and wild mustard can reduce bertha armyworm infestations in flax, peas, lentils and sugar beets. Larvae will first feed upon these weeds and then move onto these crops after the weeds have been destroyed. For best results, apply an insecticide as soon as economic thresholds are reached. A single, well-timed application of any registered insecticide applied with aerial or high clearance ground equipment is usually effective.