Invasive Species Treatment & Certified Arborist

Carroll County's forests are changing. Two invasive insects, emerald ash borer and hemlock woolly adelgid, are established in our region and actively killing ash and hemlock trees. Winter moth and browntail moth affect oaks, maples, and other hardwoods. Spotted lanternfly is advancing through the Northeast.

None of these threats are hypothetical. If you have ash trees, hemlocks, oaks, or maples on your property, some of these pests are almost certainly present in your town, if not already in your trees.

What separates trees that survive from trees that don't is usually timing. Treatment works. But only if it's applied while the tree still has the vascular capacity to circulate it.

🪲 Emerald Ash Borer (EAB)

Emerald ash borer arrived in New Hampshire gradually over the past decade and is now confirmed throughout Carroll County and into York County, Maine. Every species of ash tree is susceptible. The beetle has already killed hundreds of millions of ash trees across North America, and the pattern here will be no different without intervention.

How EAB Kills Ash Trees

Adult EAB beetles lay eggs in the bark of ash trees. The larvae hatch and bore into the inner bark, where they feed on the phloem and cambium layer, the tissue that carries water and nutrients up and down the tree. As larval galleries expand, they girdle the tree, cutting off the flow of resources. The tree starves from the top down, with crown dieback progressing over two to five years until the tree is dead.

Signs of EAB Infestation

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  Crown DiebackTop branches losing leaves while lower branches remain green. This starts at the top of the crown and works downward season by season. By the time you see significant dieback, the infestation is already several years old.
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  D-Shaped Exit HolesSmall, D-shaped exit holes about 1/8 inch across in the bark, where adult beetles have emerged. These are a reliable diagnostic sign and indicate active infestation in the previous season.
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  Woodpecker ActivityIncreased woodpecker feeding on your ash is often the first visible sign. Woodpeckers are excavating EAB larvae from under the bark. Flecking of outer bark in large patches is characteristic of woodpecker response to heavy EAB infestations.
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  Epicormic SproutingSmall clusters of shoots emerging directly from the trunk or major branches, below areas of crown dieback. This is a stress response as the tree attempts to regenerate.
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  S-Shaped Galleries Under BarkIf you peel back a section of loose bark, sinuous S-shaped feeding galleries packed with sawdust-like frass are visible beneath. This confirms active EAB larvae.

The Treatment Window

Trunk injection for EAB is highly effective when applied at the right time. Timing is everything here, and this is a point we are direct about with every customer: once a tree's crown is more than 30 to 40 percent in dieback, the tree's water-conducting system is too compromised for the treatment to circulate effectively. At that stage, treatment is no longer a reliable option.

If your tree is less than a third in decline, treatment is still a good candidate. If the tree has shown no visible symptoms, proactive treatment is the most cost-effective approach. A treated tree avoids the expense, hazard, and landscape impact of removal entirely.

Should You Treat Your Ash Trees?

The honest answer depends on the tree. A large, healthy, prominent ash in good condition is almost always worth treating. The cost of two-year protection is a fraction of removal cost, and the tree has value to your property, your landscape, and the local wildlife that depends on it.

A smaller ash in the back corner of the lot, already showing significant decline, is a different calculation. We don't push treatment on trees that aren't good candidates. We'll give you a straight assessment and let you decide.

🌲 Hemlock Woolly Adelgid (HWA)

Hemlock woolly adelgid is a small, sap-sucking insect native to East Asia. It arrived in the eastern United States decades ago and has been advancing northward as winters warm. HWA is now confirmed in parts of Carroll County and is spreading. Eastern hemlock, one of New Hampshire's most important native conifers, has no evolved resistance to this pest.

Why Hemlocks Matter Here

Eastern hemlock is not just a landscape tree. In our region, hemlock stands provide the dense canopy that keeps stream temperatures cold enough for brook trout and other cold-water fish. They provide critical thermal cover for white-tailed deer in winter. They are major components of the forest along the river corridors that feed into Ossipee Lake, the Merrymeeting River, and other waterways in Carroll County.

When a hemlock stand is lost, the stream warms, the fish leave, and the understory is replaced by invasive shrubs. The loss is ecological, not just aesthetic. This is why treating high-value hemlocks matters beyond your own property line.

Identifying HWA

Look at the underside of hemlock twigs, near where the needles attach to the twig. HWA produces small, white, woolly egg masses at the base of each needle. They look like tiny cotton balls or tufts of white fluff attached to the twig. The masses are present year-round but most visible in late winter and spring.

Infested hemlocks develop grayish-green needles (healthy hemlock needles are dark green on top and pale with two white lines below) and eventually drop needles beginning with the oldest growth. Heavily infested trees can die within four to ten years.

Treatment Options

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  Trunk InjectionSystemic treatment injected directly into the vascular system, as with EAB. Highly effective. Treatment is timed for fall and early spring when adelgids are actively feeding and most vulnerable. A single treatment provides protection for multiple seasons.
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  Soil InjectionSystemic treatment applied to the root zone, taken up by the tree through normal water uptake. Effective for smaller trees or trees in locations where trunk injection isn't practical. Takes longer to reach the canopy than trunk injection but provides season-long protection.
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  Foliar TreatmentApplied directly to foliage, effective for smaller accessible trees. Timing to the crawler stage in late spring gives the best results. Less practical for large trees with significant canopy height.

Unlike EAB, HWA treatment is effective even after infestation has begun, as long as the tree still has reasonable crown health. An infested hemlock showing 25 to 50 percent needle loss can often be treated successfully and recover substantially over the following two to three growing seasons.

Other Invasive Pests Active in Our Region

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  Spongy Moth (formerly Gypsy Moth)One of the most destructive defoliators in the northeastern United States. Spongy moth caterpillars feed on the foliage of oaks, birches, aspens, and many other hardwoods in late spring and early summer. A single severe defoliation weakens trees significantly; two or three consecutive years can kill them, particularly combined with other stresses like drought. Populations cycle and can remain low for years before resurging. We treat during the caterpillar stage in late spring when the window is open.
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  Winter MothAn invasive European moth whose caterpillars emerge in early spring and feed voraciously on the expanding buds of oaks, maples, cherries, apples, and blueberries. Repeated defoliation over several years progressively weakens trees and increases their vulnerability to other stresses and pathogens. Treatment timing is critical; applications must be made in the tight window when caterpillars are small and actively feeding. We monitor phenology to get this timing right.
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  Browntail MothA concern in coastal New Hampshire and Maine, with inland populations expanding. Browntail moth caterpillars defoliate hardwood trees and produce barbed, toxic hairs that cause a severe skin rash on contact, similar to poison ivy but sometimes more persistent. The hairs remain toxic for two to three years in the environment. Management involves treating overwintering webs in winter and spring caterpillars before they disperse. We coordinate treatment to life cycle.
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  Elongate Hemlock ScaleA different hemlock threat from HWA. Elongate hemlock scale is an armored scale insect that feeds on the undersides of hemlock needles, drawing out cell contents and causing needles to yellow and drop. Heavy infestations give hemlocks a sparse, faded appearance and progressively weaken the tree over multiple seasons. Unlike HWA, the scale is easy to miss because its flattened, elongated covers blend with needle color. Look for small, oyster-shell-shaped covers on needle undersides. Systemic treatments and targeted horticultural oil applications, timed to the crawler stage, are the most effective management approach. Hemlocks already dealing with HWA pressure are particularly vulnerable to secondary elongate hemlock scale infestations.
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  Spotted LanternflyNot yet established in our service area as of 2025, but confirmed in Massachusetts and advancing into southern New England. A significant threat to fruit trees, hardwoods, and ornamentals, especially grapes and hops. We're monitoring its spread and are prepared to respond. If you think you've seen one, report it to NH DNCR and contact us.
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  Asian Longhorned BeetleA serious threat to maples, birches, elms, and willows, confirmed in isolated areas of New England. Kills trees by boring into the heartwood. If you see large, round exit holes (3/8 to 1/2 inch diameter) in your hardwood trees, contact us and the NH DNCR. Early detection is critical for containing spread.

🚨 New Arrivals: Beech Leaf Disease and Red Pine Scale

Two threats arrived in Carroll County faster than anyone anticipated. Beech leaf disease and red pine scale have both established in the region within the past two years. This is worth paying attention to even if your trees look fine right now.

Beech Leaf Disease

Beech leaf disease is caused by a nematode, Litylenchus crenatae, that infests the leaf buds of American beech. The disease was first identified in Ohio in 2012 and has spread rapidly through New England. It reached New Hampshire within the past two years and is now confirmed in Carroll County.

The symptoms are distinctive once you know what to look for. Affected leaves develop dark, striped banding between the leaf veins, visible when held up to the light. As the disease progresses, leaves become leathery, distorted, and reduced in size. Heavily infected trees produce sparse, malformed foliage and can die within several years of initial infection.

What makes beech leaf disease particularly concerning is how quickly it spreads and the fact that American beech is already under stress from beech bark disease (see below). Trees weakened by one condition are more vulnerable to the other. Beech with both diseases present decline faster than trees with either alone.

Emerging treatments include trunk injection and soil injection of phosphonate compounds and nematicide-class materials. Research is ongoing and results vary by tree size, disease stage, and site. We evaluate each candidate tree individually and discuss the current state of the evidence before recommending treatment.

Red Pine Scale

Red pine scale (Matsucoccus resinosae) is a small sap-sucking insect that attacks red pine, one of the most common planted conifers in New Hampshire's managed forests and residential landscapes. The scale feeds in the bark and cambium layer, causing branch dieback, crown decline, and eventual tree death. Heavy infestations kill trees within two to four years.

The insect is difficult to detect in its early stages. Look for resin soaking or crystallized pitch on the bark of branches and the main trunk, yellowing and reddening of foliage that does not look like typical fall color, and unusual branch dieback that progresses from the inside of the crown outward. By the time dieback is dramatic, the infestation has usually been established for more than a year.

Red pine scale arrived in Carroll County recently and spread faster than anticipated. Planted red pine stands, windbreaks, and ornamental red pines on residential lots are all at risk. Treatment options are limited compared to some other pests, and the most important decision is whether to treat or remove before a declining tree becomes a hazard. We assess each situation honestly and tell you what your options actually are.

Long-Established Tree Diseases in NH

Not every threat is new. Some diseases have been part of New Hampshire's landscape for decades, reshaping which trees dominate and which have declined. Understanding these gives context for why proactive care matters, because we've seen what happens when threats go unmanaged at a regional scale.

Beech Bark Disease

Beech bark disease is a two-stage complex that has been moving through New Hampshire's forests for decades. It starts with the beech scale insect (Cryptococcus fagisuga), an exotic pest introduced to Nova Scotia in the late 1800s. The scale feeds on beech bark and creates wounds that allow two species of Neonectria fungi to enter and cause cankers in the bark and wood.

Infected beeches develop rough, scaly bark covered with white waxy deposits from the scale insects, followed by sunken cankers, cracks, and eventually structural failure. Heavily infected forests lose most of their mature beech within a few decades. The disease is well established throughout Carroll County and has already changed the composition of many local forest stands.

There is no cure for beech bark disease in forest trees, but individual high-value landscape beeches can be managed with scale treatments to reduce the insect component of the complex. This doesn't eliminate the disease but can slow its progression in trees that are still worth protecting. Combined with beech leaf disease now present in the same trees, the prognosis for stressed beech has become more serious over the past two years.

Dutch Elm Disease

Dutch elm disease, caused by the fungus Ophiostoma ulmi and its more aggressive relative Ophiostoma novo-ulmi, arrived in the United States in the 1930s and effectively eliminated American elm as a dominant street and landscape tree across the country within decades. It is transmitted by elm bark beetles that carry fungal spores from diseased wood to healthy trees.

The disease causes wilting and yellowing of leaves on individual branches (called flagging), which progresses through the crown until the tree dies. A cross-section of infected branches reveals brown staining in the outer rings of the wood. Once systemic infection is established, the tree cannot be saved.

Dutch elm disease is not spreading in the way it once did because most susceptible mature elms are already gone. However, younger elms that have grown back in since the initial epidemic are reaching the size and age when they become attractive to the bark beetles that spread the disease. Proactive trunk injection with systemic fungicides is available and effective for protecting high-value elms that warrant the investment. If you have a mature elm in good condition, it is worth a conversation.

Plant Health Care Services

Invasive species aside, trees and shrubs under stress from nutrient deficiency, soil compaction, or chronic disease are less able to defend themselves from any pest or pathogen. A healthy tree is a more resilient tree. Our plant health care services address the underlying conditions that make trees vulnerable.

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  Deep Root FertilizationMacro and micro-nutrients delivered directly into the root zone through pressure injection, bypassing the turf layer and reaching tree roots where broadcast surface applications cannot. Particularly valuable for trees in compacted urban soils, trees showing declining vigor, and trees recovering from stress or treatment. We calibrate formulations based on symptoms and site conditions.
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  Plant Growth Regulators (PGRs)Applied as a soil drench, PGRs reduce shoot extension and redirect the tree's energy toward root development and stress resistance. Treated trees develop deeper, more extensive root systems, improve drought tolerance, and produce higher concentrations of natural defensive compounds. PGRs are particularly useful for maintaining trees in challenging conditions: compacted soil, restricted root zones, areas under pavement or construction impact.
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  Biostimulant ApplicationsMycorrhizal inoculants, humic acids, and biological inputs that support the soil food web around tree root zones. Mycorrhizal fungi extend the effective root zone and improve water and nutrient absorption significantly. These are not a substitute for fertilization but a complement to it that improves the long-term health of the soil-root relationship.
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  Disease ManagementProactive and reactive fungicide programs for common ornamental diseases including fire blight, apple scab, cedar-apple rust, anthracnose, powdery mildew, and Diplodia tip blight on pines. Timing applications to the correct growth stage dramatically improves efficacy compared to calendar-based spraying.
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  Plant Health DiagnosticsIf something looks wrong with your trees or shrubs and you're not sure what it is, that's exactly what a diagnostic consultation is for. Our arborist has 35 years of pattern recognition in this region. Misdiagnosis leads to wasted money on the wrong treatment. Getting it right starts with looking at the problem correctly.

Common Questions

Serving Carroll County and York County

We're based in Sanbornville and have worked on trees throughout this region for decades. We know which ash species are most common here (white ash and green ash predominate in the lower elevations, with mountain ash in wetter areas). We know where hemlock stands border the cold-water streams that feed into Ossipee Lake and the Merrymeeting River. We know the soil types across the different glacial landscapes from the drumlin country around Wolfeboro to the sandy outwash soils around New Durham and Great East Lake.

That regional knowledge matters in diagnostics. A declining hemlock near Province Lake in Effingham is in a different soil environment than one on the lakefront in Tuftonboro. Symptoms that look similar can have different underlying causes. Getting the right treatment starts with understanding where the tree is living.

We serve Wakefield, Ossipee, Wolfeboro, Tuftonboro, New Durham, Freedom, Effingham, Rochester, and the surrounding NH towns, as well as Sanford, Acton, Shapleigh, and Waterboro in southern Maine.