Vegetable Crop Insect Scouting

David Owens, Extension Entomologist,

Continue scouting peppers for beet armyworm defoliation. Earworm sprays may be necessary soon as trap captures in some areas are approaching Virginia Tech’s rule of thumb of 20 per night. Also look under leaves for aphids. Pyrethroids will not provide reliable control for earworm, and they do not control beet armyworm. Frequent pyrethroid applications are the primary reason for aphid outbreaks, and this is the time of the year when aphid populations begin increasing in vegetables. Thresholds are 5 aphids per leaf.

Sweet Corn
Fall armyworm continue to be active in both whorl stage and silking corn. On sweet corn pushing tassel or just prior to first silk, be looking for signs of feeding from small or large worms on the husk leaves, especially where the silks will emerge. If you see signs of feeding (window paning, small light brown frass pellets) start your silk sprays.

Moth pressure is moderate, and is very similar to Monday. We tested 40 moths this week and had 40% survivorship. This is also not quite as high as last year, in which we peaked over 60% before settling between 40 and 50% for the month of August. Aphid populations are on the increase, so be sure to scout fresh market sweet corn. Should you need to treat for aphids, recommended products include Lannate, Assail, and Sivanto. Both Sivanto and Assail are rated as having moderate bee toxicity.

Trap counts for Thursday are as follows:

Trap Location BLT – CEW Pheromone CEW
3 nights total catch
Dover 1 58
Harrington 2 97
Milford 3 62
Rising Sun 1 78
Wyoming 0 14
Bridgeville 2 4
Concord 1 41
Georgetown 1 15
Greenwood 1  
Laurel 2 71
Seaford 3 67
Lewes 7 18
Millsboro 10 7

Spider mites and thrips are active, and you need to be thinking of worm protection with earworm catches increasing. A suggested worm threshold is one egg on 10 plants or 3% fruit damage. Thrips injury will show up as dimples on the fruit and dirty silvery streaks on the underside of leaves. In our area, in addition to what is in the Commercial Veggie Recs, Beleaf is labeled and is excellent on thrips.

Spider mites continue to be stubborn, and our weather pattern hasn’t helped any. Rotate among products so that you don’t hit the mites with the same product twice. Pay attention to pre harvest intervals.