David Owens, Extension Entomologist, owensd@udel.edu
Cucurbits
Begin scouting for two spotted spider mites. We recently posted a spider mite fact sheet that covers mite biology, natural enemies, thresholds in various crops, miticides in various crops, and miticide impacts to beneficials: https://www.udel.edu/academics/colleges/canr/cooperative-extension/fact-sheets/two-spotted-spider-mite/. Cucumber beetles are still moving through to fields.
Snap Bean
Scout now for leafhopper; thresholds are 100 adults and nymphs per 20 sweeps. If a spray is warranted, there are a variety of active ingredients to choose from, including pyrethroid, carbamate, OP, neonic 4A and 4D materials. Bean leaf beetle are also active, treat when defoliation reaches 20%. BLB feeding injury can look like someone took a hole punch to the leaves.
Sweet Corn
Several universities in the mid-Atlantic, including University of Delaware, are planning to pursue research funds for improving our understanding of corn earworm biology and economics in sweet corn under current conditions, and we need your help. Your feedback in a survey developed by Dr. Kelly Hamby at UMD is extremely valuable as we identify objectives and demonstrate research need to potential federal programs. Please take a few minutes to provide feedback! Survey link: https://ume.qualtrics.com/jfe/form/SV_9vRh1xHnDp4KEaa
Corn Earworm Moth Counts
We installed our blacklight and pheromone trap network at the beginning of May. Now that the first sweet corn plantings are tasseling, we will be reporting on most recent trap captures. You can find trap counts from earlier in the week, as well as historical data and spray timing recommendations here: https://www.udel.edu/academics/colleges/canr/cooperative-extension/sustainable-production/pest-management/insect-trapping/.
| Trap Location | BLT – CEW | Pheromone CEW |
| 3 nights total catch | ||
| Dover | 2 | 32 |
| Harrington | 0 | 12 |
| Milford | 2 | 42 |
| Rising Sun | 0 | 0 |
| Wyoming | 3 | 26 |
| Bridgeville | 0 | 14 |
| Concord | 4 | 9 |
| Georgetown | 0 | 14 |
| Greenwood | 0 | 24 |
| Laurel | 3 | 7 |
| Seaford | 2 | — |
The biggest adjustment that probably should be made to the spray schedule recommendation is to tighten spray schedule intervals by 1 day when the temperature is above 80 degrees, particularly during the first 10 days. Begin treating when 10-20% of silks are out and if emerging tassels were not already infested.
Moth counts are going to steadily increase to our typical mid- to late-June peak. We are also trapping for European corn borer this year at 5 locations (Laurel, Concord, Greenwood, Milford, and Rising Sun), but have not yet captured an ECB in pheromone traps.