Understanding the Threat

The emerald ash borer is a non-native wood-boring beetle introduced from Asia that has devastated ash populations across the Midwest. In Minnesota, where ash trees represent nearly one in five urban trees, the economic and environmental impact has been significant. The beetle’s larvae tunnel through the cambium layer just beneath the bark, disrupting the tree’s ability to transport water and nutrients. Once a tree shows visible symptoms, the infestation has often been active for a year or more.

Burnsville’s location in the Twin Cities metro places it squarely within the established quarantine zone. State regulations now restrict the movement of ash wood across county lines to slow the spread, but the beetle continues to expand its range. Late summer presents the best opportunity for detection because adult beetles are actively feeding on ash foliage, and tree stress becomes most visible when temperatures peak and trees are under natural water strain. Homeowners who inspect their ash trees in August have a much clearer picture of tree health than those who wait until fall or spring.

Recognizing the Signs

Visual symptoms develop gradually, beginning in the upper canopy where initial dieback often goes unnoticed from ground level. Thinning branches at the top of the tree, especially when they appear on one side first, signal stress that may indicate an active infestation. The most diagnostic sign is the presence of small, D-shaped exit holes in the bark. These holes, roughly the size of a grain of rice, appear when adult beetles emerge in late spring and early summer.

Bark splitting is another key indicator. Vertical cracks form as the tree responds to larval feeding, and peeling back loose bark often reveals serpentine galleries carved by larvae as they feed. Woodpeckers recognize infested trees as a food source, so increased woodpecker activity, visible as patches of stripped bark, can signal an underlying problem. Epicormic sprouting, where dense clusters of small shoots emerge from the trunk or base, represents the tree’s stress response. Finally, canopy dieback exceeding thirty percent, particularly if it occurred rapidly over one or two growing seasons, warrants immediate evaluation. Ash trees under stress from other causes may show similar symptoms, which is why a professional inspection provides the clarity needed to make an informed decision.

Making the Right Choice

Deciding whether to treat or remove an ash tree requires balancing the tree’s current health, location, and long-term value against the cost and commitment of ongoing care. Trees showing minimal canopy loss, generally under thirty percent, and no structural damage remain strong candidates for treatment. Trunk injections of systemic insecticides offer protection for two to three years per application, making this a recurring investment rather than a one-time solution. The treatment works best when started before visible symptoms appear, which is why proactive evaluation matters.

Trees that have already lost significant foliage, developed structural weakness from woodpecker damage or bark splitting, or sit near structures where failure poses a safety risk are better candidates for removal. The challenge many homeowners face is waiting too long to act. Dead or dying ash trees lose structural integrity quickly. The wood becomes brittle, branches fail unpredictably, and removal becomes more dangerous and costly. A tree that could have been removed safely in early stages may require specialized rigging, crane access, or piece-by-piece dismantling once it has declined significantly. Location also plays a role in the decision. A tree providing shade over a deck or driveway, blocking a sight line, or anchoring a landscape design may justify the cost of treatment, while a tree in a less prominent location may not.

The Evaluation and Service Process

A professional evaluation begins with a visual inspection of the canopy, trunk, and surrounding landscape. Certified arborists look for the symptoms described earlier, assess the tree’s overall structural health, and consider site-specific factors such as proximity to buildings, utility lines, and other trees. If treatment is appropriate, the process involves injecting insecticide directly into the trunk using specialized equipment. The procedure typically takes less than an hour per tree and causes minimal disruption to the property. No trenching, heavy equipment, or landscape disturbance is required.

If removal is necessary, the scope of work depends on the tree’s size, location, and condition. Removal typically involves sectioning the tree from the top down to control the fall of each piece, then grinding the stump below grade so the area can be replanted or restored. In Minnesota, ash wood from quarantined areas must be disposed of according to state guidelines, which often means chipping on site or transporting to approved facilities. Reputable providers handle permitting, disposal, and site cleanup as part of the service. Homeowners should expect clear communication about timing, access needs, and any temporary disruption to driveways, lawns, or landscaping. Most residential removals are completed in one day, leaving the property clean and ready for replanting.

The Urgency of Late Summer

August offers the clearest window for accurate assessment because trees are fully leafed out, stress is visible, and adult beetle activity is still detectable. By the time leaves drop in fall, symptoms become harder to interpret, and by winter, visual inspection alone may miss early-stage infestations. Homeowners who schedule an evaluation now gain the time needed to make an informed decision, budget for treatment or removal, and complete the work before the ground freezes or spring demand spikes.

The cost of waiting extends beyond the tree itself. A declining ash tree drops branches unpredictably, threatens nearby structures, and can affect property values if visible decline becomes severe. Once a tree is dead, removal costs increase due to the added complexity and risk. Scheduling an inspection in late summer positions homeowners to act from a place of clarity rather than crisis. Whether the outcome is a treatment plan that preserves a valued tree or a removal that eliminates a growing liability, the decision becomes easier when made with accurate information and adequate time. For Burnsville-area properties with ash trees, this month represents the best opportunity to take control of the situation before winter arrives and options narrow.