Sweet Corn IPM Newsletter No. 12 — September 11, 2026
Last Issue for 2026 — Pest Pressure Lower In Late Season Corn
Corn Earworm and Fall Armyworm Numbers Fall as Dry Conditions Continue
This will be the final issue of the Sweet Corn IPM Newsletter for the 2026 season. I would like to thank all of the growers who participated in the program this year, and our IPM scouts, including Marianne Renaud, Christina Howard and Sean McAuley. Special thanks to Stephanie Wright for editing and mailing the newsletter and updating our webpage. We will be sending you an evaluation form for our newsletter and the Corn IPM Program this fall. Please fill it out and let us know how you use the information we provide and how it impacts your pest management decisions. This information will help guide the future direction of this program.
Situation
As the sweet corn season winds down there has been little relief from severe drought conditions affecting much of the state. Pest pressure has moderated some this week, as the weather pattern has not favored increased insect activity. The forecasts are not calling for any significant change in the situation in the near future.
European corn borer: No moths were captured this week.
Corn earworm: Moth counts were generally lower this week, and many farms were able to relax their spray schedule a bit. However, all sites remain on a regular spray interval for corn earworm on all fresh (green) silking corn. Most farms now have only corn with dried silks remaining, which should not be susceptible to earworm unless pressure is very high. A 6-day spray interval for silking corn was recommended for one site in Wells. A 5-day spray interval was recommended for Bowdoinham, Corinth, Dayton, Monmouth, Oxford and one Wells site. A 4-day spray interval was recommended for Biddeford and Cape Elizabeth.
Fall armyworm: Moth numbers declined at most sites this week but still exceeded the threshold of three moths per week in silking corn at Biddeford, Bowdoinham, Cape Elizabeth, Corinth and Monmouth. All sites are presently on a spray interval for corn earworm for fresh silking corn. However, an additional spray may be warranted for fall armyworm on corn with dry silks, because the larvae may tunnel into the sides of the ears.
Western Bean Cutworm: No moths were caught in our traps this week.
Annual end of corn season checklist:
- Plow down corn stalks and stubble to destroy overwintering larvae of European corn borer.
- Plant a cover crop, such as winter rye, to prevent soil erosion and to add organic matter to the soil.
- Take a soil test to determine if lime or other nutrients should be applied.
- Rotate your crops next season to prevent pests from building up in any one location.
- Evaluate your weed management results; What worked well and what didn’t? Which weeds were the biggest problems? How can you improve control?
- Clean and winterize spray equipment, put away and properly store any unused pesticides.
Vegetable and Berry Growers Twilight Meeting
The twilight meeting will be held on Thursday, September 17 at 5:30 p.m. at Goss Berry Farm in Mechanic Falls, Maine.
New England Vegetable and Fruit Conference
The New England Vegetable & Fruit Conference will be held in Manchester, New Hampshire on December 15, 16, 17, 2026. Registration is open now and program information will be coming soon.
Sincerely,
David T. Handley
UMaine Extension Vegetable & Small Fruit Specialist
Highmoor Farm
P.O. Box 179
52 U.S. Route 202
Monmouth, ME 04259
207.933.2100
UMaine Extension Diagnostic Research Lab
Pest Management Unit
17 Godfrey Drive
Orono, ME 04473
1.800.287.0279
| Location | CEW Moths | ECB Moths | FAW Moths | WBCW Moths | % Feeding Damage | Recommendations / Comments |
|---|---|---|---|---|---|---|
| Biddeford | 8 | 0 | 12 | 0 | – | 4-day spray interval recommended for silking corn |
| Bowdoinham | 5 | 0 | 9 | 0 | – | 5-day spray interval recommended for silking corn |
| Cape Elizabeth | 88 | 0 | 14 | 0 | – | 4-day spray interval recommended for silking corn |
| Corinth | 4 | 0 | 5 | – | – | 5-day spray interval recommended for silking corn |
| Dayton | 4 | 0 | 2 | 0 | – | 5-day spray interval recommended for silking corn |
| Monmouth | 6 | 0 | 26 | 0 | – | 5-day spray interval recommended for silking corn |
| Oxford | 5 | 0 | 0 | 0 | – | 5-day spray interval recommended for silking corn |
| Wells | 3 | 0 | 0 | 0 | – | 6-day spray interval recommended for silking corn |
| Wells II | 4 | 0 | 2 | 0 | – | 5-day spray interval recommended for silking corn |
CEW: Corn earworm (Only fresh silking corn should be sprayed for this insect.)
ECB: European corn borer
FAW: Fall armyworm
| Moths caught per week | Moths caught per night | Spray Interval |
|---|---|---|
| 0.0 to 1.4 | 0.0 to 0.2 | No spray |
| 1.5 to 3.5 | 0.3 to 0.5 | Spray every 6 days |
| 3.6 to 7.0 | 0.6 to 1.0 | Spray every 5 days |
| 7.1 to 91 | 1.1 to 13.0 | Spray every 4 days |
| More than 91 | More than 13 | Spray every 3 days |
Thresholds apply only to corn with exposed fresh silk. Lengthen spray intervals by one day if maximum daily temperature is less than 80°F.
European Corn Borer Thresholds
Whorl stage: 30% or more of plants scouted show injury.
Pre-tassel-silk: 15% or more of plants scouted show injury.
Silk: 5 or more moths caught in pheromone traps in one week.
IPM Web Pages:
Explore Integrated Pest Management in Maine — UMaine
Integrated Pest Management — UMass Amherst
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