Vegetable Crop Insect Scouting

David Owens, Extension Entomologist, owensd@udel.edu

Asparagus
Asparagus beetles continue to be active. There are extension recommendations to treat if half to ¾ of ferns are infested with beetles or their larvae. Labeled materials include Permethrin, Malathion, carbaryl, Lannate, and the group 5 insecticides Entrust and Radiant.

Cucurbits
Continue scouting for spider mites and for aphids in watermelons. For the most part, we are in between cucumber beetle treatments, and fields that did not need to be treated for cucumber beetle (threshold is 2 beetles per plant) may experience aphid pressure in spots. Aphids can be treated with numerous insecticides, some of which are rather aphid specific and extremely safe for bees, particularly the group 9 insecticides (Fulfill, Sefina, and PQZ) and 29 insecticides (Beleaf). Now that fruit is forming, be sure to look for signs of rind feeding. Lepidopteran rind feeding is going to be a wide, smooth and even scar whereas cucumber beetle rind scarring is going to look ‘dirty’, uneven, and rough. If Lep feeding is noticed, there are numerous worm-specific insecticides that will not risk flaring spider mites, including Intrepid, Coragen, Avaunt, Radiant, and Proclaim. Avoid pyrethroids as much as possible, overuse can flare mite populations.

In squashes, treat for squash vine borer, and scout for aphids.

Potatoes
Continue scouting for potato leafhopper and for Colorado potato beetle. Leafhopper activity is increasing, and Colorado potato beetle should be pupating and new adults should be appearing soon.

Peppers
In small plots at the REC, tomato hornworm were working small pepper plants. The good news is that hornworms are relatively easy to control if necessary.

Sweet Corn
Insect traps continue to decrease throughout the state. We are heading into what I call our ‘July lull’. Most sweet corn can probably be put on a 4 day or a 3-4 day spray schedule; 3 following a pyrethroid and 4 following a Besiege or Elevest. Bird cherry oat aphids were observed in isolated hot spots in a field this week by a consultant. This is rather interesting as in other crops, they are fairly easy to control with pyrethroid insecticides. This could be a coverage issue or could be that the pyrethroids are suppressing them to a greater extent than otherwise would happen. If you feel that aphid pressure is building and threatening to result in honeydew on the ears, Assail, Sivanto, and possibly Lannate (depending on the aphid species) are the best aphid products. Please note that Assail has 2 different rates, a low rate with a 1 day PHI that can be used every 7 days and a higher rate with a 7 day PHI but may offer suppression on sap beetles. There are generic formulations of acetamiprid and there is a new liquid formulation.

Thursday trap counts are as follows: