David Owens, Extension Entomologist; owensd@udel.edu
Sweet Corn
Moth Vial Testing
We have resumed corn earworm vial testing for pyrethroid resistance. Moth survivorship currently runs at 34% (44 moths treated). This means that additional modes of action should be featured in a spray program. Incorporation of a diamide (Coragen or Harvanta) or a pre-mix product (Besiege) will be necessary. Other products that can be included in a spray rotation include Radiant or Blackhawk and Lannate. If you are experiencing heavy moth pressure and are relying on pyrethroids alone, spray schedules should be tightened. If other modes of action are in your spray rotation, your spray schedule should be fine. If you are fortunate to receive a heavy rain event, consider re-treatment a little sooner, especially if the previous application did not have a diamide.
Trap Counts:
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. Moth counts from Monday are as follows:
| Trap Location | BLT – CEW | Pheromone CEW |
| 4 nights total catch | ||
| Dover | 3 | 75 |
| Harrington | 1 | 41 |
| Milford | 0 | 55 |
| Rising Sun | 0 | 43 |
| Wyoming | 4 | 147 |
| Bridgeville | 1 | 51 |
| Concord | 1 | 35 |
| Georgetown | 1 | 14 |
| Greenwood | 0 | |
| Laurel | 2 | 63 |
| Seaford | 1 | 36 |
| Trap Pond | 5 | 9 |
| Lewes | 0 | 33 |
| Dover | 3 | 75 |
| Harrington | 1 | 41 |
Cucurbits
Continue scouting for spider mites. Mite populations in weather like we are having can increase 10x in a week. The first watermelons are being harvested now. This is a good time to assess fruit for rind feeding injury caused by worms and cucumber beetles. Your insights on who causes what type of scar and how much is acceptable and how much is unacceptable is greatly appreciated.