David Owens, Extension Entomologist, owensd@udel.edu
Sweet Corn
Moth trap captures have declined due to a combination of cool nights and decreasing attractive resources near our pheromone traps. This is a general reminder that the most effective trap is going to be right next to silking sweet corn; our traps are by and large placed in a static location. Case in point is Concord and Milton traps which are right next to silking sweet corn right now. Also please note that the blacklight traps are still by and large indicating a 3 day spray schedule, although we may be on the cusp of a 4 day spray schedule. With warmer nights, day activity could increase quickly. Thursday trap counts are as follows:
| Location | Blacklight Trap | Pheromone Trap |
| Dover | 2 | 25 |
| Harrington | 2 | 12 |
| Milford | 6 | 25 |
| Rising Sun | 2 | 26 |
| Wyoming | — | 31 |
| Bridgeville | 2 | 7 |
| Concord | 7 | 83 |
| Georgetown | — | — |
| Greenwood | 4 | 22 |
| Laurel | 10 | 41 |
| Milton | — | 29 (2 nights) |
Lima Beans
A question came this week: when are lima beans safe from tarnished plant bug? There is very little research to draw on for this pest system. Dr. Galen Dively, Entomology Professor Emeritus, at University of Maryland had a student a while back ask this question and they found tarnished plant bugs strongly preferred blossoms and pin pods. Esquivel published a paper in 2015 in the Journal of Economic Entomology after measuring the penetration length of tarnished plant bug mouthparts. They can penetrate a mean of 584 ± 5.1 micrometers (range from 317 to 912 micrometers). We measured pod thickness for various stages of pods. See image below.
Essentially, we confirmed that pin pods are the largest size pod that tarnished plant bug can penetrate and damage the developing seed. There’s a chance they can get slightly larger, 1-inch pods, but I suspect they would ignore those and focus their attention on the smaller pods and the blossoms.
Cole Crops
If your cole crops are developing heads, this may be an excellent time to put in a long lasting or translaminar product for worm protection. Heads can be difficult to protect with contact only materials or even contact materials that need to be ingested. If using BT, please note BT and Copper are not compatible!
Be sure to identify your worm complex! Cabbage loopers are less susceptible to Torac. Diamondback moth, beet armyworm, corn earworm, and fall armyworm are less or hardly susceptible to pyrethroids. Corn earworms and the armyworms tend to ‘sit’ on the growing point and completely consume it.