Sweet Corn IPM Newsletter No. 14 — September 13, 2024

COOL NIGHTS KEEP PEST PRESSURE LOW

Fall Armyworm and Corn Earworm Threat Lower in Most Locations

This will be the final issue of the Sweet Corn IPM Newsletter for the 2024 season. I would like to thank all of the growers who participated in the program this year, and our IPM scouts, including Leo Anderson and Sean McAuley. Special thanks to Stephanie Wright for editing and mailing the newsletter and updating our webpage and blog. We will be sending you an evaluation form for our newsletter and the Corn IPM Program this fall. Please take the time to 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

Not many fields are left with corn in the silking stage or younger. Many later planted fields matured earlier than expected due to the warm growing conditions in July and early August. Corn earworm and fall armyworm numbers were lower this week, likely due to cooler night temperatures and no southern storms coming through. The prediction for the coming week is for warmer than normal weather, so there may be an increase in pest activity, and any silking corn remaining should continue to be protected.

Corn earworm: Moth activity was generally low this week as cool night temperatures and fair weather continue to moderate insect activity. For sites that no longer have corn in the fresh silk stage, earworm is not a threat. A 6-day spray interval for silking corn was recommended in Bowdoinham, Dayton and Oxford; a 5-day spray interval was recommended in Gray and Wayne; a 4-day spray interval was recommended for Cape Elizabeth. No earworm moths were caught at our sites in Biddeford, Monmouth, and Wells.

Fall armyworm: Moth counts in pheromone traps were generally lower than last week, but still high enough to recommend continued protection of silking corn. Biddeford, Bowdoinham, Cape Elizabeth, Dayton, Gray, Monmouth, Wayne and one site in Wells were over the three-moth threshold for silking corn in pheromone traps. Biddeford, Monmouth and the Wells location were not presently under a spray interval for corn earworm, so protective sprays were recommended.

Annual end of corn season checklist:

1. Plow down corn stalks and stubble to destroy overwintering larvae of European corn borer.
2. Plant a cover crop, such as winter rye, to prevent soil erosion and to add organic matter to the soil.
3. Take a soil test to determine if lime or other nutrients should be applied.
4. Plan to rotate your crops to prevent pests from building up in any one location.
5. Evaluate your weed management results; What worked well and what didn’t? Which weeds were the biggest problems? How can you improve control?

Maine Vegetable and Small Fruit Growers Twilight Meeting

Maine Vegetable & Small Fruit Growers Twilight Meeting: Join the MVSFGA for a twilight meeting at Blackies Farm Fresh Produce, 966 Minot Ave in Auburn on Tuesday October 1. We will see the new packing, washing and storage facilities and get an update on new pesticide products and how best to manage applications under new regulations. Meet and greet starts at 5:30 p.m. and the program will start at 6 p.m.

The New England Vegetable & Fruit Conference will be held in Manchester, NH December 17, 18, 19, 2024. Program and registration information will be coming soon. Visit the website: http://www.newenglandvfc.org/

 

Sincerely,

David T. Handley
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

CEW: Corn earworm (Only fresh silking corn should be sprayed for this insect.)
ECB: European corn borer
FAW: Fall armyworm
CBW: Western bean cutworm

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

Where brand names or company names are used, it is for the reader’s information. No endorsement is implied nor is any discrimination intended against other products with similar ingredients. Always consult product labels for rates, application instructions and safety precautions. Users of these products assume all associated risks.

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