Table 2 summarizes the insecticides, crops, rates of application and preharvest interval. 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. Apply the insecticide early in the morning or late evening when the larvae are actively feeding. Do not apply during warm afternoons.