MDA warns emerald ash borer found near Brainerd; outlines quarantines, detection and treatment options

Jonathan Ossus, emerald ash borer technical assistance coordinator with the Minnesota Department of Agriculture's Plant Protection Division, said the department identified emerald ash borer (EAB) in the Brainerd area and urged residents and communities to begin planning management now. "We have nearly a billion ash trees in the state," Ossus said, noting the insect was first identified in Minnesota in 2009 and that 48 counties now have known infestations.

The finding near Brainerd in Crow Wing County prompted a review of biology, signs and responses. Ossus described EAB's life cycle, saying adult beetles are active from May through September, females lay on average 60 to 90 eggs in a lifetime (sometimes more), and larvae tunnel in the cambium, creating S-shaped galleries that girdle trees. He said the insect typically takes about five years from initial infestation to tree death and that earlier detection improves management outcomes.

Danielle DeVito, plant pest regulatory coordinator at MDA, explained the department's quarantine system aimed at slowing spread. "Red is stop: you cannot leave those areas without an agreement," DeVito said, describing internal (state) and external quarantine layers, the definition of regulated articles (all parts of ash trees, the insect itself, mulch and hardwood firewood under four feet) and the compliance agreements that allow businesses and municipalities to move material under specified treatments and handling standards.

MDA staff emphasized practical detection tips and community actions. The most reliable early indicator is woodpecker feeding in the canopy that produces blonded patches and small shallow holes; Ossus said other signs include bark splits, D-shaped exit holes and finding larvae with two small tail spines (urogomphi). He advised that trees with roughly 30 percent or less canopy decline may still be treatable and recommended property owners consider preventive insecticide treatment if they are within about 10 to 15 miles of a known infestation.

On treatments, Ossus said professional trunk injections of emamectin benzoate (a restricted-use product) are commonly used for large trees and typically provide about two years of protection; he recommended professional application for trees above roughly 15 inches in diameter and offered a ballpark of about $10 per diameter inch as a market estimate for professional treatments. For communities, he recommended combining selective removals (especially poor-quality trees), sanitation removals of symptomatic trees in winter and targeted treatment of high-value specimens to stagger canopy loss.

The department asked the public to report suspected infestations with clear photos and precise location information. "If you find an insect, please capture it and, you know, stick it in a plastic bag and put it in the freezer," Ossus said, and directed reporters to EDMAPS, MDA's 'report a pest' online form, email or voicemail for submissions. DeVito said MDA posts an updated EAB status map and provides a "safe to move" certified seal for kiln-heat-treated firewood.

Ossus closed by announcing free one-hour field workshops in March to view infested trees in person (Brainerd: March 19'20 at JC's Park; Dilworth/Moorhead area: March 26'27) and said the recorded briefing and resources will be posted on the MDA EAB dashboard and YouTube. He encouraged municipalities, tree-care companies and residents to contact MDA for compliance agreements and guidance.

The department did not announce new regulatory changes beyond quarantine enforcement; no votes or formal actions were recorded during the briefing.