Vegetable Crop Insect Management – April 22, 2016

Joanne Whalen, Extension IPM Specialist;

Be sure to scout for asparagus beetle adults and eggs on newly emerged spears. Feeding by beetles can disfigure spears. Depending on the market, the presence of eggs on the spears can make them unmarketable. As a general guideline, a treatment is recommended if 2% of the spears are infested with eggs or if 5% of the plants are infested with adults.

Continue to scout fields for imported cabbage worm and diamondback larvae. Low levels of larvae can now be found. Sprays will be needed before they move deep into the heads. As a general guideline, a treatment is recommended if you find 5% of the plants infested with larvae.

Continue to sample fields for aphids. The continued cool weather favors increases in populations. 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. When sampling dry land peas, you may want to reduce the threshold, especially if they become drought stressed.

As soon as plants emerge, be sure to sample fields for Colorado potato beetle adults, especially if an at-planting material was not used. The first emerged adults can now be found. A treatment should not be needed for adults until you find 25 beetles per 50 plants and defoliation has reached the 10% level

Sweet Corn
The earliest planted fields should be scouted for cutworms. A number of cutworm species may be present at planting, including the black cutworm, dingy cutworm and clay backed cutworm. Regardless of the species, treatments should be applied for cutworms if you find 3% cut plants or 10% leaf feeding. Please refer to the Commercial Vegetable Recommendations for suggested chemical controls: