David Owens, Extension Entomologist, owensd@udel.edu
Sweet Corn
Moth counts remain elevated in most of the state, except for a curious hole around Georgetown. As such, we have not been able to test very many moths this week. Out of 26 tested moths, survivorship this week is only 23%.
Thursday corn earworm moth capture is as follows:
| Trap Location | BLT – CEW | Pheromone CEW |
| 3 nights total catch | ||
| Dover | 2 | 131 |
| Harrington | 1 | 16 |
| Milford | 0 | 127 |
| Rising Sun | — | 82 |
| Wyoming | 0 | 47 |
| Bridgeville | 4 | 61 |
| Concord | 2 | 15 |
| Georgetown | 1 | 19 |
| Greenwood | 6 | — |
| Laurel | 3 | 65 |
| Seaford | 2 | 28 |
| Lewes | 2 | 107 |
| Dover | 2 | 131 |
Cole Crops
Be sure to scout transplants carefully, worms can quickly do heavy damage on small plants. Last year, about 10% of my transplants turned into spears almost overnight because a yellow striped armyworm found the plants as soon as I put them out to harden off. This year, cabbage looper and imported cabbageworm tried to do the same. Cabbage looper is very active. Thresholds for early stage plants are 20% infested plants. Remember to rotate modes of action from one spray to another and to rotate modes of action out every 30 days. Good coverage is essential, and in many cases, use of an adjuvant will help improve control on the waxy leaves. Do not use binder or sticker adjuvants when using diamides or Radiant, these products try to get across the leaf membrane into the tissue, while stickers try to keep the product on the surface.
Watermelon
Lepidopteran rind worms are still active, including cabbage looper and beet armyworm. Beet armyworm is attracted to pigweed and can be found in pigweeds in and around fields, feeding on the top leaves. If looking at pigweed, make sure that you find the worm, there are other caterpillars that feed on pigweed leaves that do not get into watermelon. Beet armyworm is resistant to pyrethroids, you will need a worm product. Of the worm products, Exirel and Harvanta have some beetle activity and will stop adults from feeding. Cucumber beetle larvae will also etch rinds on the ground spot but unlike the caterpillars, there are no remedial options. Larvae that are present now came from F1 beetles that were active at the beginning of July.
Cucurbits
Aphids continue to colonize cucurbit fields, and in some areas, pressure can be heavy. You can quickly find large colonies by looking for shiny honeydew on plastic, lower leaves, and fruit. Large infestations may also result in thickened and cupping new leaves. The good news is that we have numerous options for controlling aphids, and the most consistent results have been achieved with foliar applications.