David Owens, Extension Entomologist, owensd@udel.edu
Sweet Corn
Corn earworm counts have come down slightly over last week, but still in the high category, indicating a 3-day spray schedule for most areas where our traps are at. Temperatures are forecast to climb Sunday. During the first 10 days of silking under high pressure and high temperatures, I recommend a 2-day spray interval following a pyrethroid and a 3-day interval following Besiege or Elevest.
Trap counts and spray intervals can be found on our website: https://www.udel.edu/academics/colleges/canr/cooperative-extension/sustainable-production/pest-management/insect-trapping/.
Thursday trap counts are as follows:
| Trap Location |
BLT CEW |
Pheromone CEW |
| 3 nights total catch | ||
| Dover | 11 | 110 |
| Harrington | 10 | 61 |
| Milford/Canterbury | 14 | 147 |
| Rising Sun | 18 | 50 |
| Wyoming | 23 | 91 |
| Bridgeville/Redden | 5 | 18 |
| Concord | 10 | 95 |
| Georgetown | 5 | 70 |
| Woodenhawk | 10 | 120 |
| Laurel | 11 | 110 |
| Lewes | – | 18 |
Tomatoes
Untreated late tomatoes in Georgetown are getting hit hard by corn earworm. Continue regular worm sprays.
WE ARE LOOKING FOR TOMATO FIELDS. Last year we found a predatory mite, Phytoseiulus persimilis in a late tomato field in October in eastern Sussex County. This mite is a spider mite specialist, the only thing it eats are two spotted spider mites. We visited a tomato field in central Sussex this week with the main objective of putting up an earworm pheromone trap and collect a few mites for a student. We ran into P. persimilis in that field as well. We want to know where else the mite can be found. Please help us gain a better understanding of this important beneficial mite by giving us permission to look at your late tomato field and sending us the location. My email is owensd@udel.edu and cell 302 698-7125. Thanks!
Spinach
Beet webworm is very active right now. If you are growing spinach, be on the lookout for beet webworm folding leaves and causing window-paning. Beet webworm loves pigweeds and spinach is a close relative.
Cole crops
It is no surprise that all our Cole crop pests are active. Two to be especially wary of are corn earworm and beet armyworm. Beet armyworms are attracted to fields with pigweeds and are pyrethroid resistant. Corn earworm can be devastating to a cabbage plant and is much less susceptible to pyrethroids. Unlike a lot of our other cabbage worms, corn earworm goes for the growing point and gets a bit larger than the other species. Aphids are beginning to increase, and harlequin bugs, left unchecked, can quickly cause significant damage to Cole crops.