Minnesota Agriculture Dept. proposes aerial pheromone treatment across 34,000 acres in Winona County to slow spongy moth spread

The Minnesota Department of Agriculture told the Winona County Board it is proposing a targeted aerial mating-disruption program for the spongy moth over five blocks that together total about 34,000 acres across Winona, Goodview, Alba, Stockton and Minnewaska. "Our goal today is to come and share a little bit about our program," said Kimberly Tilling Kramers of the Department of Agriculture, who presented the department's plan and biology of the pest.

The department said the project uses a pheromone-based product marketed as Splat Gypsy Moth Organic to disrupt male moths' ability to locate females. Kramers described Splat as "EPA-certified organic, nontoxic, biodegradable and species specific," and said the technique is intended to prevent mating rather than kill large numbers of caterpillars. The department plans a single application timed to precede the male moth flight in the late-June to early-July biological window; the application would be made by low-flying aircraft and is expected to take several days across a larger Southeast Minnesota operation.

Why it matters: Spongy moth feeds on hundreds of tree species and in outbreak years can cause widespread defoliation that harms oak and other canopy trees. State officials said the program's purpose is to slow westward spread along the leading edge and to limit the chance the pest becomes established across new counties.

Funding and process: Kramers emphasized that the operation depends on federal funds the department usually receives; the project would be canceled or delayed if those funds do not arrive in time for the biological window. The department also said it performs environmental assessments for threatened and endangered species and other local impacts before operations begin. "We do legal notices, press releases and we'll push out email and text notifications so citizens know when aircraft will be in the air," Kramers said, adding that counties and cities will be notified ahead of general public notice.

Public outreach and safety: The department described a statewide monitoring network of more than 20,000 early-detection pheromone traps and said officials will hold virtual and local public meetings before treatment. Kramers acknowledged residents will see low-flying aircraft and suggested advance county and media notice to reduce alarm. The department urged residents to report suspect egg masses or caterpillars rather than simply destroy them, to help with surveillance.

Next steps: The department will coordinate public meetings and county notifications, refine a schedule about a week to 10 days before operations, and proceed only if necessary federal funding and environmental clearances are confirmed. County commissioners said they expect public questions about aircraft over residential areas and asked staff to post explanatory material to the county website in advance.