David Owens, Extension Entomologist; owensd@udel.edu
Beans
Thrips, leafhoppers, and defoliators are all active or becoming active. Action thresholds for snap bean pests can be found at http://extension.udel.edu/blog/ipm-processing-snap-beans-scouting-guidelines-2003/.
Sweet Corn
Sweet corn pheromone and blacklight traps are checked twice weekly on Mondays and Thursdays. By Tuesday and Friday morning, 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: http://extension.udel.edu/ag/insect-management/insect-trapping-program/action-thresholds-for-silk-stage-sweet-corn/. Moth counts are steadily decreasing, but we are still getting ‘fresh’ looking moths. Thursday’s trap capture is as follows:
| Trap Location | BLT – CEW | Pheromone CEW |
| 3 nights total catch | ||
| Dover | 1 | 2 |
| Harrington | 0 | 26 |
| Milford | 1 | 8 |
| Rising Sun | 0 | 18 |
| Wyoming | 1 | 10 |
| Bridgeville | 1 | 20 |
| Concord | 1 | 15 |
| Georgetown | 1 | 25 |
| Greenwood | 0 | 0 |
| Laurel | 0 | 7 |
| Seaford | 0 | 4 |
| Harbeson | — | — |
| Trap Pond | 2 | 19 |
| Lewes | — | 17 |
Watermelon
Spider mites are beginning to move into fields from woodlines and ditch edges. While these are the first places mites typically show up, hotspots can develop in field interiors, either from mites that came in with transplants or were blown into fields. With warm weather in the forecast, keep an eye out for mites moving from the edge to the interior of fields.
Squash
According to degree day models, squash vine borer should’ve started flying last week statewide. Start scouting the bases and vines of winter squash for the presence of eggs or larval tunneling signs. Once larvae enter the vine, they are protected from foliar insecticide applications. In small plantings, larvae can be dissected out of the vines carefully. Soil should be mounded up over the vine to encourage adventitious roots at the cut site. I have also heard some folks have success with injecting Bt using a syringe at the site of a larval tunnel. Sprays directed to the vine may help reduce larval desnity, but sprays would have to be frequently reapplied because adult squash vine borers are active over an extended period of time.