David Owens, Extension Entomologist, owensd@udel.edu
Cucurbits
Continue scouting for aphids and for squash bug in pumpkins. Aphid populations typically peak this time of year and heavy populations can spread viruses and cause sooty mold to develop on fruits. Squash bug populations are also typically high. Unfortunately, the best materials to treat squash bug contribute to aphid population increases. Scout for second generation cucumber beetle. Assail is the best material for cucumber beetle control (threshold around 2 per plant), followed by Harvanta (an excellent worm product), carbaryl, Lannate, and lastly pyrethroids. Note that carbaryl, Lannate, and pyrethroids are all highly toxic to pollinators.
Cole Crops
All worm species are active, especially cabbage looper, diamondback moth, and cross striped worms. Aphids and whitefly have been colonizing recently transplanted cabbage at an unusually high rate in Georgetown. Harlequin bugs are also a threat. These three groups can be treated with neonicotinoid insecticides, while you will need a good worm material for the others if cole crops reach or exceed thresholds (10% for new plants, 30% for established plants, 5% for heading plants).
Spinach
Continue scouting for Beet armyworm and Hawaiian beet webworm; note that pyrethroid efficacy has been questionable in New Jersey for Hawaiian beet webworm and do not work against beet armyworm.
Sweet Corn
Next week, temperatures are forecast to be near or below 82, thus, no temperature adjustment is necessary to spray programs. Blacklight trap counts are still elevated across the region although pheromone trap counts are trending lower, thus, unless a trap near or adjacent to your sweet corn indicates a low population, most places are justified to be on a 3-day spray schedule.
Thursday trap counts are as follows:
| Location | Blacklight Trap | Pheromone Trap |
| Dover | 10 | 44 |
| Harrington | 24 | 77 |
| Milford | 28 | 87 |
| Rising Sun | 31 | 179 |
| Wyoming | — | 106 |
| Bridgeville | 3 | 96 |
| Concord | 14 | 136 |
| Georgetown | — | — |
| Greenwood | 8 | 66 |
| Laurel | 22 | 104 |
| Milton | — | 238 (F-M) |
| Lewes | — | 106 (F-T) |
Tomatoes
Continue scouting for and taking precautions against worm damage to late tomatoes. There are numerous materials recommended in the commercial vegetable guide for worm control. Please note that the insect growth regulators novaluron and methoxyfenozide are most effective on SMALL worms, not medium or larger worms. Also note whether stink bugs are active and include a stink bug material as appropriate.