Vegetable Crop Insect Scouting

David Owens, Extension Entomologist, owensd@udel.edu

Cucurbits
Cucumber beetles are declining even in fields that were not treated early, we probably won’t see them again until the 2nd week of July. Mites continue to be the arthropod focus for right now. Be sure to do some follow up checking on miticide efficacy. If you have a field where the product did not work as expected, please let me know, I would like to collect some mites to start a colony. As mentioned last week, we are starting to see an increase in caterpillar activity. So far, I have only seen very small caterpillars feeding on the underside of leaves. Control measures may be necessary if you start seeing rind damage on the developing fruit.

In other cucurbits, all main pests are very active. Aphid populations flared up on me on an early watermelon planting but are declining now. Squash bugs and vine borers are active.

Sweet Corn
We tested another 40 moths this week in treated vials. Survivorship is averaging 20% for this week. Do not rely on a pyrethroid by itself in a spray rotation. Moth pressure has declined a little bit more at most trap sites but are still indicating the potential for moderate pressure. Also keep in mind that a pheromone trap in the immediate vicinity of silking sweet corn is the best placement for monitoring moth activity, whereas we do not move our traps. Thus, for a period of time, our trap could be right next to silking corn for only a relatively short period of time.

Monday and Thursday trap data is uploaded to our website: https://agdev.anr.udel.edu/trap/trap.php. For reference, action thresholds based off of blacklight and pheromone trap can be found here: https://www.udel.edu/academics/colleges/canr/cooperative-extension/sustainable-production/pest-management/insect-trapping/silk-stage-sweet-corn/. Thursday’s trap capture is as follows:

Trap Location BLT – CEW Pheromone CEW
3 nights total catch
Dover 1 76
Harrington 0 68
Milford 1 28
Rising Sun 1 73
Wyoming 0 4
Bridgeville 1 35
Concord 1 48
Georgetown 0 43
Greenwood 0
Laurel 1 86
Seaford 0 31
Lewes 2 24
Millsboro 3 4

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