How To Identify And Treat Common Tree Diseases And Pests In Maryland 

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After all the time and energy you’ve put into your home’s landscaping, it can be disheartening to see it succumbing to common tree diseases and tree pests.

When left untreated, some of these common tree diseases – which can be identified with signs like wilting leaves, brown spots, and dead bark – can actually end up killing the tree… and infecting other trees in your yard and in your neighborhood.

Those are, of course, worst case scenarios. But how do trees even get sick in the first place? How can you as a homeowner recognize what they’re sick with? And what can you do to keep those illnesses from spreading?

Today we’re sharing more about the root cause of common tree diseases in Maryland, the tell-tale signs of ones prevalent in our area, as well as some of the tree pests you might encounter.

Why Stress Leads To Common Tree Diseases

While life as a tree can seem pretty ideal – lots of time outdoors, plenty of sunshine – trees can get stressed just like we do.

(Well, maybe not just like we do! I haven’t seen too many trees sitting in traffic late for work.)

So, what causes a tree to get stressed? In addition to drought and overcrowding, which can lead to competition for resources, tree stress can come from:

  • Root damage – This interferes with a tree’s ability to collect water from the surrounding area, stressing its internal systems
  • Damage to the tree’s stem – This can become an entry point for diseases, leading to infection

Just like the stress of a long week can lower your defenses, these environmental stressors can compromise the defenses of our trees. This can become a gateway to a number of common tree diseases and tree pests in Maryland.

Common Tree Diseases in Maryland

Below you’ll find some of the more common tree diseases in Maryland, as well as how to identify them and how to treat them.

Oak Wilt

This is a fungal disease that affects oak trees and is spread by beetles. It causes the leaves to wilt and turn brown, and can ultimately kill the tree.

The fungus can also cause black streaks in the sapwood of the tree, which can be visible when the bark is removed.

The most effective treatment is prevention, which involves avoiding wounding oak trees during pruning or other activities. 

If oak wilt is detected, the infected tree should be removed and destroyed immediately, as the fungus can spread to nearby trees through root grafts.

Dutch Elm Disease

A fungal disease that affects elm trees and is spread by bark beetles. It causes the leaves to yellow and wilt, and can lead to the death of the tree.

The disease can cause a distinct “flagging” pattern, where branches on one side of the tree die and turn brown, while the rest of the tree appears healthy.

There is no cure for Dutch Elm Disease, but infected trees can be treated with fungicides if caught early enough. In severe cases, the tree may need to be removed and destroyed to prevent the spread of the disease.


A fungal disease that affects a variety of trees, including sycamore and dogwood, anthracnose causes leaf spots and defoliation. Over time, this can end up weakening the tree.

The disease can also cause cankers, or areas of dead bark, on the trunk and branches of the tree.

Pruning infected branches and improving tree health through proper watering and fertilization can help reduce the severity of anthracnose. 

In severe cases, fungicides may be necessary.

Apple Scab

A fungal disease that affects apple trees, causing black or brown spots on leaves and fruit, apple scab result in defoliation and reduced fruit yield.

The disease can cause the fruit to become distorted and cracked, and can also affect the twigs and leaves of the tree.

Fungicides can be used to treat apple scab, but it is also important to maintain good tree health through proper pruning, watering, and fertilization.

Common Tree Pests in Maryland

In addition to the diseases that can cause problems in your yard, there are a number of tree pests that may be eyeing your landscaping for their next home.

Emerald Ash Borer

A beetle that attacks and kills ash trees by feeding on the inner bark, disrupting the tree’s ability to transport water and nutrients.

Infested ash trees may exhibit thinning canopies and increased woodpecker activity, as the birds feed on the beetle larvae.

Insecticides can be used to protect healthy ash trees from emerald ash borer infestation. At a certain point, it may also be necessary to remove and destroy infected trees to prevent the spread of the pest.

Gypsy Moth

A caterpillar that feeds on the leaves of a variety of trees, including oak and birch, and can defoliate large areas of forest.

Gypsy moth caterpillars leave behind large amounts of frass (droppings), which can be visible on the ground and on the tree’s trunk and branches.

Insecticides can be used to control gypsy moth populations, and physical barriers such as burlap can be used to prevent caterpillars from climbing the tree.

Eastern Tent Caterpillar

A caterpillar that creates webs in the branches of trees and feeds on leaves, causing defoliation. 

The webs created by the caterpillars can be large and unsightly, and can lead to increased damage from other pests and diseases.

Eastern tent caterpillars can be controlled through pruning and removing the webs by hand, or through the use of insecticides.

White Pine Weevil

A beetle that attacks the terminal leader of white pine trees, causing the top of the tree to die back and the tree to become misshapen.

White pine weevil infections may also be noticed from the appearance of resinous droplets on the bark, as well as affected branches becoming crooked or bent downward.

Insecticides can be used to protect healthy white pine trees from weevil infestation, and infected trees can be pruned to remove the affected branches.

Professional Tree Services To Help Keep Your Yard Healthy

Depending on the seriousness of the disease or the level of infection, there are different ways you can address them. At Beautiful Country Tree Services, we’re here to help, whether that’s in pruning back infected branches or removing one tree to protect the rest of the yard.

To learn more about the best course of action for your landscaping, we encourage you to get in touch with our team today.