Joanne Whalen, Extension IPM Specialist; firstname.lastname@example.org
Be sure to watch for imported cabbage worm (ICW) and diamondback moth larvae (DBM) within a week of transplanting. As a general guideline, treatment is recommended if you find 5% of the plants infested with larvae. If DBM is the predominant species, be sure to select an insecticide that is effective for this insect pest since it can be difficult to control. The pyrethroids have not provided effective control of DBM in many cases, especially where resistance has been documented. Please refer to the Commercial Vegetable Recommendations for suggested chemical controls
As soon as plants emerge, be sure to sample on a weekly basis for pea aphids. On small plants, you should sample for aphids by counting the number of aphids on 10 plants in 10 locations throughout a field. On larger plants, take 10 sweeps in 10 locations. As a general guideline, a treatment is recommended if you find 5-10 aphids per plant or 50 or more aphids per sweep. Although beneficial insects can help to reduce aphid populations, cool temperatures will favor an increase in aphid populations but will slow beneficial insect activity. As a general rule, you need one beneficial insect per every 50-100 aphids to help crash populations.