leaves wilting and falling off even though the tree or shrub is getting enough water

black, brown, orange, or yellow spots on leaves

chewed and ragged edges on leaves

leaves with so many holes they look like lace

With our specialized equipment and extensive training, we safely and efficiently remove trees on both residential and commercial properties.

Fungal & Bacterial Diseases

Flowering trees are especially susceptible to diseases that not only make them look unsightly but can also cause decline and eventual death. For example, you've probably seen apple scab and fireblight on crabapples, anthracnose on dogwoods, and cedar-apple rust on apple trees.


  • blotches, or dark or yellow spots on leaves
  • brown, crispy leaf edges
  • rotting or spotted fruit
  • fuzzy white or grey growth on leaves
  • dying needles on conifers
  • browning leaves and premature defoliation
  • dying branch ends
  • cankers or oozing sores on branches and tree trunks

Leaf- & Tree-Damaging Insects

There are many insects that damage (or even kill) trees in the Hudson Valley area of New York. Emerald ash borers have decimated ash trees across the state, caterpillars eat all the leaves off trees, and new invasive pests like the spotted lanternfly keep moving in.


  • holes or ragged/chewed edges on leaves
  • silk webs, threads, or "tents" on branches
  • holes in tree bark (especially on ash trees)
  • a tree that suddenly loses leaves in spring or summer
  • yellowing, curling, or speckled leaves
  • bumps on stems and small branches
  • sticky substance (and maybe black mold) on leaves or under the tree
  • an unusual number of insects flying around the tree

Pest & Disease Prevention & Control

Early identification of problems, quick diagnosis of the cause, and appropriate treatment are key to controlling insect pests and diseases, and preventing irreparable damage to your trees and landscape.

Our tree health programs provide preventive care or treatments for a wide range of tree and shrub pests and diseases. Examples of common pests and diseases we can help you with include:


Apple Scab


Boxwood Blight

Boxwood Leafminer

Japanese Beetles

Spotted Lanternfly

Dutch Elm Disease

Oak Wilt

Emerald Ash Borer


Hemlock Wooly Adelgid

Scale Insects

Spider Mites

Ticks & Mosquitoes

Tent Caterpillars

Gypsy Moth

Powdery Mildew

Bacterial Leaf Scorch

Needlecast & Needle Blight


Early identification of insect infestation, diseases, and soil problems is critical

Don't wait until it's too late to save your tree! Call the ISA Certified Arborists at Hill Treekeepers as soon as you notice anything unusual.

Tree Disease and Insect Treatments


We offer a range of treatments for insect pests, fungal problems and bacterial diseases. Treatments are customized to treat the issues while minimizing effects on beneficial insects and other living creatures.


WHEN? Spring and fall

This lightweight natural oil is sprayed on trees to suppress pests such as scale, adelgids and mites.


WHEN? 3 - 4 treatments in spring to early summer

Applied as a spray to leaves and tree trunks to prevent fungal leaf diseases, such as scab, anthracnose, and rust.


WHEN? As needed during growing season

Used for immediate control of damaging insect pests. The appropriate timing and insecticide is chosen to target the specific pest (rather than using a broad-spectrum insecticide that would harm all insects).


WHEN? Spring

A systemic insecticide injected into the tree's root zone to prevent problems with leaf-chewing and sap-sucking insects, such as leaf miners, scale, and Japanese beetle.


WHEN? Mid-May to mid-June

A special insecticide is injected directly into the soil around the tree or sprayed on the bark. From there, it is distributed throughout the living parts of the tree to kill EAB larvae. Details about EAB


When a soil test shows that the soil on your property is lacking in specific nutrients or is outside the optimum pH level, fertilization can help fix the problem.


WHEN? Spring and/or fall

A custom blend of nutrients is injected into the soil in the tree's root zone where it can more easily take up the nutrients it needs. Soil injection also prevents problems from fertilizer runoff.

For more details, see our FAQs about tree fertilization, including whether or not trees really need to be fertilized.

Why Trust Hill Treekeepers To Keep Your Trees Healthy?

We know you have choices when it comes to selecting a Hudson Valley tree service to care for your trees.

Properly licensed by the state of New York

We encourage you to check the pesticide business license of any tree service company you hire (it's required to apply chemicals used to treat tree and landscape problems).

ISA Certified Arborists

To ensure that all issues are correctly diagnosed and treatments are used appropriately

Free estimate and a detailed proposal

So you'll know exactly what's wrong with your trees and what we plan to do

Locally owned and operated since ....

Founded, owned, and operated by a life-long Hudson Valley resident

All work is done with strict adherence to professional tree care standards (ANSI A300 Standards)

To protect your health, your trees, and the environment

Frequently Asked Questions About Tree Treatments & Fertilization

PHC stands for Plant Health Care, which is a fancy way of saying that we do all of the things necessary to keep plants (including trees!) healthy. That includes fertilization and soil improvement, as well as identification, control and prevention of problems caused by pests and diseases.

Integrated Pest Management (IPM) is a streamlined, ecological approach to pest management that gives you more effective results with less need for harmful chemicals. It's more effective in controlling the “bad bugs” in your yard and is safer for people, pets, and the environment compared to the traditional method of spraying everything with insecticide. Plus, IPM saves you money that would’ve otherwise been spent on unnecessary pesticides.

IPM includes regular monitoring of pest populations, the use of biological and cultural controls, applying physical controls, planting pest-resistant varieties, and using organic pesticides.

The goal of IPM is to manage pest populations for long-term prevention, not necessarily to eradicate them entirely. If pest populations are kept down, they’ll cause fewer problems and little noticeable damage in your yard or garden.

The best time to apply treatments depends on the problem.

Some tree diseases, for instance, are only stopped through preventive treatments that must be applied before the disease has affected your tree. For example, trees and shrubs that are prone to certain fungal leaf diseases (such as anthracnose) are preventively treated three times a year, usually in late spring and early summer. Once the disease is visible, it’s too late to treat it.

Other treatments are applied only when the problem, whether it’s a pest or disease, is present. For example, treatments that work by making contact with the pest or coating leaves that they're feeding on must be applied when the pest is active. 

Early identification of problems, quick diagnosis of the cause, and appropriate treatment are key to controlling insect pests and diseases, as well as preventing irreparable damage to your trees and landscape.

If you think something is wrong, contact us for an inspection. We'll diagnose the problem, determine the health of your tree or shrub, and give you a prognosis and treatment plan.

Treatment is often possible if the problem is caught soon enough. In other cases, your tree or shrub may have already declined to the point that it could be beyond saving (in which case, quick and safe tree removal would be best).

That depends. Many of the most effective insect and disease treatments can only be applied by professionally licensed pesticide applicators. While there are some options available to homeowners to treat small trees, these require careful application to avoid unintended environmental impacts.

For example, products can leach into groundwater and some products are highly toxic to pollinators and aquatic invertebrates.

We've also seen many cases of homeowners misdiagnosing the problem and applying toxic treatments that don't have any positive effect.

Large or tall trees are very difficult to treat effectively without specialized equipment, such as a high-powered spray rig to reach the upper parts of the tree or a tree injection kit for systemic pesticides. In general, we recommend having larger trees treated by a professional with the knowledge and equipment to do the job correctly.

If you have trees, chances are you'll need to fertilize them.

Trees that grow in forests and woodlands get their nutrients from the soil they grow in, but in urban and suburban areas the soil has usually been severely depleted of nutrients and organic matter.

Many homeowners throughout the Hudson Valley notice that some of their trees show signs of nutrient deficiency (such as yellowing leaves and stunted growth). In other cases, a soil test shows that 


DO Fertilize if Your Tree is Damaged or in Decline

Trees that have been damaged by storms, construction, pests or diseases, or over-pruning (including aggressive utility right of way pruning) will often benefit from supplemental fertilization, including in summer.

When a significant number of branches or roots have been broken or removed, trees aren’t able to produce enough energy or absorb enough nutrients to help them stay healthy. Plus, pests and diseases can make it more difficult for trees to thrive. The result is a noticeable decline in the number of leaves and increased yellowing.

Gentle fertilization, such as with deep root injections of compost tea, can help damaged and declining trees recover.

If you think your trees and shrubs need fertilization, it’s important to know what nutrients they need and how much fertilizer to apply. Fertilizer runoff is a serious problem when too much fertilizer is used. And too much nitrogen and phosphorus cause problems for trees, such as decreased fruiting and preventing the uptake of other key micronutrients.

The best way to find out what nutrients your trees and shrubs need is to get a soil test from a qualified testing lab, such as the Cornell Soil Health Laboratory, or through your arborist. You’ll get information about nutrient levels in your soil, and instructions on how much fertilizer is needed to balance your soil’s fertility.

If you think the cost of a professional soil test isn’t worthwhile, we urge you to reconsider. You may find soil test kits in hardware stores and nurseries that are cheaper than a laboratory analysis. But their results are neither precise nor guaranteed, and professionals don’t use them.

That depends… Generally, spring and early fall are the best times of year to fertilize trees in southern New York state. But you can also fertilize in summer IF your tree needs it AND you use a gentle fertilizer like compost tea.

Besides the time of year, there are a number of other times when fertilizer should be used.

Are your trees showing signs of insect infestation, diseases, or soil problems?

Call the ISA Certified Arborists at Hill Treekeepers to diagnose and treat the problem quickly and safely.