David Owens, Extension Entomologist, owensd@udel.edu
Corn
Outside of very sporadic cutworm activity, corn insect pests are quiet right now. Continue scouting for cutworm and stink bug on young plants prior to V5-V6. Stink bug are usually only associated with late terminated small grain cover crop. NCSU uses a threshold of 13 bugs per 100 plants.
Soybean
Injury and damage from seedcorn maggot is apparent in some fields. Continue scouting emerging beans, particularly in New Castle County and nearby areas of Maryland for slug feeding. Typically slug impact wanes after Memorial Day.
Defoliator pests of note that are active right now include bean leaf beetle, green cloverworm, and grasshopper. Grasshopper eggs have begun hatching. While we do not have a threshold for grasshopper in the mid-Atlantic, keep note of areas with high nymph activity. If defoliation begins to reach 30%, a treatment may be advisable.
Sorghum
Scout for grasshopper and cutworm injury in young sorghum and for stand injury from slugs in no-till fields. Sorghum can tolerate as much as 15% stand loss without significant yield loss. Grasshopper thresholds vary but in general are between 5 and 8 nymphs per square yard. Their populations tend to be greatest around field borders and especially near drainage ditches.
Sunflower
For the second time in consecutive years, slugs have destroyed emerging sunflower in my garden. We observed severe slug feeding on sunflower a couple of years ago in eastern Sussex County. Check sunflower plots to make sure that an adequate stand has indeed emerged, particularly in no-till fields.
Alfalfa
Scout alfalfa for potato leafhopper. Our insect management guide has a dynamic threshold table incorporated, accounting for plant size and value of hay, and control cost. Check it out: https://www.udel.edu/content/dam/udelImages/canr/pdfs/extension/sustainable-agriculture/pest-management/Insect_Control_in_Alfalfa_-2023.pdf
Early Season Moth Activity
This is the last report for cutworm and armyworm moth activity. Many thanks to Joanne Whalen and Dvid Armentrout for providing assistance. Trap counts are as follows:
| Location | # of Nights | Total Catch | |
| TAW | BCW | ||
| Salisbury, MD | 7 | ||
| Seaford, DE | 7 | 0 | — |
| Sudlersville, MD | 7 | 0 | 7 |
| Harrington, DE | 7 | 3 | 21 |
| Smyrna, DE | 7 | 4 | 0 |
| Middletown, DE | 7 | 1 | 29 |