David Owens, Extension Entomologist, owensd@udel.edu
Sweet Corn
Continue scouting whorl stage corn for fall armyworm. New Jersey is not reporting new infestations, however this is typically the time we start seeing them here.
For corn earworm, with the high heat this week, it is advisable to tighten treatment intervals by a day, especially when following a pyrethroid or pyrethroid/Lannate application. Moth counts are gradually increasing, in some areas it may be best to tighten to a 2 to 3-day spray schedule while others could still be around a 3 to 4-day spray schedule. Many thanks to Dick Monaco and Morgan Marzec for checking traps. Thursday moth captures are as follows:
| Trap Location | BLT – CEW | Pheromone CEW |
| 3 nights total catch | ||
| Dover | 1 | 21 |
| Harrington | 1 | 64 |
| Milford | 2 | 36 |
| Rising Sun | 1 | 74 |
| Wyoming | 1 | 26 |
| Bridgeville | 1 | 15 |
| Concord | 2 | 19 |
| Georgetown | 0 | 33 |
| Greenwood | 1 | 18 |
| Laurel | 2 | 8 |
| Seaford | 1 | 0 |
| Lewes | — | 5 (2 nights) |
Cucurbits
Striped cucumber beetles continue to emerge from the soil. New adults have a white and black stripe appearance. In trials, we have had good efficacy from Assail, Harvanta, and Carbaryl. Carbaryl can flare mites. Cyantraniliprole, the active ingredient in Exirel and Minecto Pro, also has cucumber beetle activity, and Exirel is labeled for beetles. Pyrethroid efficacy in trails at Salisbury last year was quite disappointing.
When scouting for striped cucumber beetle at this time, check melon rinds for signs of beetle or worm damage, and look for feeding injury on blossoms.
Scout for mites and treat accordingly. Mite populations in hot dry weather can increase 10x per week, and if melons are under stress from harvesting and from carrying a full fruit load, they become much more susceptible to mites.
Squash bugs are increasing. If nymphs are not yet present, wait for egg masses to begin hatching before treating. Pyrethroids, Assail, and Sivanto should provide good control. Use higher water rates and try to get good coverage into the canopy. Squash bugs hide during the day near plant bases and underneath residue. One note, Besiege at its highest label rate is equivalent to a Warrior application. It might be useful if squash vine borer is still active in the planting, otherwise, the chlorantraniliprole component is not effective on squash bugs.
Tomato
Reports have come in this week of stink bug damage to tomato. Stink bugs are very difficult to scout for in the crop, and stink bugs are like little tanks. Pyrethroids, Lannate, and foliar neonics imidacloprid, thiamethoxam and dinotefuran are labeled. Please note that the neonics are all highly bee toxic. I also did not include acetamiprid, as it is not as effective on stink bugs. Use high water rates, 50-100 gallons, and high pressure. Dr. Jerry Brust wrote an excellent article on stink bugs in tomatoes in last year’s edition of the WCU (ironically at the exact same time of the year: https://sites.udel.edu/weeklycropupdate/?p=18972. Please note that even once controlled, stink bug damage will appear for a while as fruit with feeding injury matures.
Cole Crops
Harlequin bug populations are increasing rapidly. With hot drier weather, diamondback moths may become more abundant.