David Owens, Extension Entomologist, owensd@udel.edu
Sweet Corn
The 2022 Corn Earworm flight has begun. Some of our traps have recorded massive increases in the last four days. At least at one of our locations, we have a trapping study in a block of silking sweet corn. Those traps are capturing far more CEW than our ‘location trap’. Tightening spray schedules for fresh market sweet corn is advised to go to a 2-day spray interval following a pyrethroid and a 3-day spray interval following a Besiege or Elevest application. Also, fall armyworm are active in fairly low numbers. Pheromone trap counts are fairly low; at Georgetown we caught 14 last week. Spotty whorl infestations are present. New Jersey has reported heavy infestations in the Cape May region in the past few days. Remember, armyworm kick their feeding into high gear in the last three days of larval development. This means that often by the time damage is easily noticeable, the worms may have already completed their development. Look for windowpaning and signs of fresh feeding in the whorl. Also please note that spotted cucumber beetle feeding can superficially look like early instar armyworm windowpaning. If a tassel or whorl stage sweet corn application is desired, it would be better to save the chlorantraniliprole active ingredient in Besiege and Elevest for silk sprays. I rank the pyrethroid active ingredients as follows: Hero (high rate)>Baythroid>=Brigade>=Warrior>Permethrin. Trap counts are as follows:
| Trap Location | BLT – CEW | Pheromone CEW |
| 3 nights total catch | ||
| Dover | 2 | 51 |
| Harrington | 1 | 77 |
| Milford | 3 | 81 |
| Rising Sun | 3 | 30 |
| Wyoming | 1 | 63 |
| Bridgeville | 1 | 38 |
| Concord | 2 | 36 |
| Georgetown | 1 | 68 |
| Greenwood | 2 | 32 |
| Laurel | 2 | 32 |
| Seaford | 1 | — |
| Lewes | — | 296 |
Tomato
As noted, corn earworm are very active now and will continue to be so. It takes 2-3 days for eggs to hatch, and a few more days for larvae to grow large enough to cause damage. Thus, if worm sprays have not already been a regular part of a maintenance schedule, they are advisable either towards the end of the coming week or beginning of the week after. Spider mites are also active. Remember thresholds are 2-4 mites per upper canopy leaflet.
Watermelon
Beet armyworm and corn earworm are active, along with a host of miscellaneous rind feeding worms. It is notoriously difficult to scout for active worm infestations. Rind injury unfortunately does not disappear. Record keeping is very important to document whether or not rind feeding appears to be increasing or static. Armyworm and earworm are not as susceptible to pyrethroids as other rindworms, consider a ‘worm’ material if rind feeding is a concern.
Pepper
Scout for beet armyworm infestation. Beet armyworm early instars feed together and spin silk in the upper canopy. They are resistant to pyrethroid insecticides.