David Owens, Extension Entomologist, owensd@udel.edu
Early Season Moth Activity
Early season moth activity continues to be low. I do not anticipate any issues with armyworm. A report of black cutworm activity in soybean came in this week. Next week will be the last week of maintaining these traps. Many thanks to Joanne Whalen, Haley Sater, Ben Sammarco and Victoria Smith for checking traps this season.
| Location | # nights | True Armyworm | Black Cutworm |
| Salisbury, MD | 7 | 4 | 8 |
| Laurel, DE | 7 | 4 | 9 |
| Seaford, DE | 7 | 5 | 11 |
| Harrington, DE | 7 | 3 | 7 |
| Suddlersville, MD | 7 | 3 | 8 |
| Smyrna, DE | 7 | 24 | 32 |
| Middletown, DE | 7 | 0 | 0 |
Soybean
Check establishing stands for signs of insect or slug injury to stands. Reports have come in of sporadic damage caused by seedcorn maggot and cutworm over the last two weeks. Remember, soybeans can compensate impressively well for stand loss. If the stand is fairly uniform, irrigated soybeans in the 60-80,000 range can yield just as well as a more conventional target stand. A neat picture came in of what appeared to be tarnished plant bug or garden fleahopper feeding on unifoliate leaves. There are not established thresholds for these, as long as the beans appear to be growing then this type of feeding should be cosmetic only.
Corn
Check fields planted in late terminated cover crop for signs of cutworm and stink bug feeding. Stink bugs will eave a row of symmetric, ragged holes in the leaves and if severe enough may cause plants to tiller excessively. Look at the base of plants on the stalk below the lowest green leaf for stink bug. NCSU recommends treating if there are more than 13 stink bugs per 100 plants. Cutworm thresholds are 3% cut plants at V1-V2 and 5% cut plants at V2-V4.
Alfalfa
After the first cutting, begin scouting for potato leaf hopper. Typically, this pest arrives at the end of May/early June. It secretes a phytotoxic saliva when it sucks sap from the plants resulting in hopperburn and less plant vigor. By the time hopper burn can be seen, yield loss has already occurred. There is a dynamic threshold table listed on our website at https://www.udel.edu/content/dam/udelImages/canr/pdfs/extension/sustainable-agriculture/pest-management/Insect_Control_in_Alfalfa_-2023.pdf