Vegetable Crop Insect Scouting

David Owens, Extension Entomologist, owensd@udel.edu

Cucurbits
Continue scouting for spider mites in melons. We have seen an unusually active mite year. I suspect these are mites that started in transplant houses and were planted into fields. I am just now finding mites beginning to feed on lower leaves of pokeweed along wooded edges. Now that fruit is beginning to grow on the early planted watermelons, pay attention to rind worms. There are numerous species of Leps that will lay eggs and feed on leaves, some of which could cause injury to the developing fruit. We have a wide variety of good Lep products available. A couple of notes: Bt should not be mixed with Bravo. Neither should Agri-mek or Zeal be mixed with ‘sticky’ fungicides such as Bravo. While I have seen these tank mixtures do well recently, the combination can result in reduced efficacy.

In other cucurbits, squash bugs are very active. This week begin scouting for squash vine borer activity.

Sweet Corn
Vial Testing: We tested another 40 moths this week in treated vials. Survivorship is averaging 30% for this week. Do not rely on a pyrethroid by itself in a spray rotation.

Trapping: Moth pressure has dropped a little bit in pheromone but not in the blacklight. This is why we run both and use the most conservative of the two, in some sites this is the black light, while in others it is the pheromone. Curiously, the black light trap in Lewes has been catching extremely large numbers of moths this week. 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/. I apologize for an earlier post that had our previous web address, this is the correct link. Thursday’s trap capture is as follows:

Trap Location BLT – CEW Pheromone CEW
3 nights total catch
Dover 4 16
Harrington 2 112
Milford 5 40
Rising Sun 0 85
Wyoming 1 6
Bridgeville 2 35
Concord 2 62
Georgetown 2 22
Greenwood 2
Laurel 5 26
Seaford 4 23
Lewes 24 74
Harbeson 3

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