Prevention is Key: Protecting Your Northern Virginia Trees from Disease Outbreaks

Trees in Northern Virginia face constant assault from a formidable array of diseases. Fungi, bacteria, viruses, and other pathogens are ready to exploit any opportunity to infect your valuable landscape trees and shrubs. From deadly oak wilt to disfiguring powdery mildew, tree diseases can quickly turn your lush property into an unsightly, unhealthy mess if left unchecked. But there are some simple steps you can take to prevent tree diseases from taking hold.

This comprehensive guide covers an Integrated Pest Management (IPM) approach to stopping common Northern Virginia tree diseases before they start. You’ll learn:

  • Key signs that disease may be infiltrating your trees
  • Planting and maintenance tips to boost tree resistance to disease
  • How beneficial insects are front-line disease fighters
  • Why pruning properly is crucial for tree health and disease prevention
  • When chemical treatments for tree diseases are – and are not – warranted

Don’t let invisible pathogens silently wreak havoc on your landscape. Implementing an IPM plan allows you to get ahead of diseases and keep your property looking its best year-round. Keep reading to start safeguarding your trees today.

Key Takeaways About Preventing Tree Diseases

  • Implement an Integrated Pest Management (IPM) plan that focuses on cultural, biological, mechanical, and chemical practices to prevent and manage tree diseases.
  • Watch for early signs of disease, like dead branches, thinning foliage, spots on leaves, and fungal growth, to catch infections early.
  • Plant disease-resistant tree cultivars, native species, and a variety of trees to limit the spread of diseases.
  • Maintain tree health through proper planting, watering, pruning with sterilized tools, and mulching to boost resistance.
  • Use biological controls like beneficial insects and mechanical controls like traps before considering chemical treatments as a last resort.
  • Consult certified arborists for creating an IPM plan, identifying diseases, and safely applying any needed chemical treatments.

Preventing Common Northern Virginia Tree Diseases

Preventing tree diseases often boils down to following an Integrated Pest Management (IPM) approach. These plans provide a holistic approach to caring for your trees and shrubs. IPM also considers the environment and how best to protect plants and organisms that aren’t pests.

The four main pillars of an IPM plan are:

Implementing an IPM program will often end up being more economical in the long run and leave you with healthier and better-looking trees. Instead of applying chemicals indiscriminately, IPM guidelines seek to first prevent disease and use the environment to your advantage.

Our team at Riverbend Tree Service follows these principles and can provide a comprehensive plan for protecting your trees from destructive diseases and insect pests.

Common Northern Virginia Tree Diseases to Watch Out For

Some of the common northern Virginia tree diseases to watch out for include:

  • Thousand cankers disease
  • Powdery mildew
  • Anthracnose
  • Oak wilt
  • Beech leaf disease
  • Laurel wilt
  • Fire blight

These diseases range in severity from minor problems causing aesthetic damage to fatal illnesses that could wipe out multiple trees on your property.

Many tree diseases only target specific species or cultivars. Take stock of the trees and shrubs on your property so you’ll know what to look for and what diseases might affect your trees in the future.

Cultural Practices to Limit the Spread of Tree Diseases

Cultural practices are things you do to limit the introduction of pests and diseases into your yard. The goal is to prevent pest and disease problems from occurring or to keep them at a level that doesn’t require treatment.

Watch for Early Signs of Disease on Your Trees

Keeping an eye out for warning signs of disease in your trees is one of the best ways to prevent the disease from spreading to more plants. Early detection may even save trees in some instances.

Detecting early warning signs is usually a simple matter of giving your trees and shrubs a quick inspection throughout the year. While different diseases have various symptoms, some of the telltale signs of an infection include:

  • Dead branches
  • Increased pest activity
  • Thinning foliage
  • Discolored leaves
  • Spots on leaves
  • Early leaf drop
  • Cracks in the bark
  • Defoliation
  • Fungal spores on the trunk

You can also hire an ISA Certified Arborist to inspect your trees for any signs of disease. While many diseases have obvious signs, others are much harder for a layperson to detect.

PRO TIP: The earlier you detect an infection, the higher the probability of saving a tree and preventing the disease from spreading to healthy trees. For some diseases, once visible symptoms become obvious, it may already be too late to save the tree.

A member of our team at Riverbend planting a tree in McLean, Virginia

Plant the Right Trees & Do It Properly

A healthy, unstressed tree better resists disease than one dealing with problems since its initial planting. Planting a tree properly will lower the risk of disease in the future.

Proper tree planting doesn’t just mean using the proper techniques (though that will keep your tree healthier and more disease-resistant). It’s important to also choose the right tree for the right place.

Different trees will thrive in different environments, from the amount of sunlight they receive to how much water they need and the type of soil they prefer. Also look at the preferred hardiness zone for any trees you consider planting (for most northern Virginia residents, this will either be 7a or 7b).

You can also limit the risk of spreading tree diseases by choosing trees that are native to our region. Of course, these trees are also at risk of diseases, but they may be more able to fight them as they won’t be struggling to survive in an inhospitable environment. Some native trees to consider for your property include:

  • Northern red oak
  • Sassafras
  • White oak
  • Chickasaw plum
  • American beech
  • Flowering dogwood
  • American holly
  • River birch

We also recommend planting a variety of trees and shrubs, rather than many of one species. Most diseases have a narrow range of trees they affect; having a wide variety of plants can limit any disease spread and keep it contained to only a few trees.

Choose Disease-Resistant Cultivars

If you’ve noticed trouble with certain diseases in the past or if there has been a recent outbreak of a tree disease in northern Virginia, consider planting disease-resistant cultivars of your favorite trees.

Breeders create these cultivars to resist pathogens that cause diseases, such as fungi, bacteria, viruses, nematodes, and oomycetes. Ask an arborist about disease-resistant cultivars they recommend to help protect your yard from northern Virginia tree diseases.

Proper Watering Improves Tree Health and Limits Diseases

While you may not often think about watering your trees, it is a way to keep them healthy during drought conditions. Recently planted trees are more susceptible to drought-related stress, so ensure you provide enough water whenever nature doesn’t. Avoid overwatering your trees, as this may damage the roots, leaving the tree stressed and more susceptible to fungal diseases and root rot.

You should also avoid overhead watering (such as with sprinkler systems that wet the foliage on trees and shrubs) as it encourages fungal growth. Water at the edge of the tree canopy with drip irrigation or a hose set to a low flow so water can soak into the ground to reach the tree roots.

WARNING: You may not think about it, but drought conditions can happen in the winter. Make sure your trees are still getting water in winter if we have a dry one.

A team member from Riverbend pruning a tree in Rockville, Maryland.

Prune Trees Properly & Use Clean, Sharp Tools

Pruning your trees regularly is a good way to keep them healthy and looking beautiful. However, improper pruning can have the opposite effect, harming the tree and leaving it more vulnerable to infection from a disease. Hiring a professional tree service to handle your tree pruning will limit the risk of damage to your trees. Our team at Riverbend Tree Service follows the ANSI A300 standards to properly and safely prune a tree.

If you choose to prune your own trees, follow these guidelines:

  • Use the right tool for the job: Using a large chainsaw will likely lead to excess damage to the tree. Instead, opt for hand pruners, loppers, or pruning saws depending on the branch’s size.
  • Keep your tools sharp: Sharp pruning tools make clean cuts. Clean cuts limit the damage to your tree, allowing it to recover more quickly and limit exposure to disease. Sharpen your pruning tools regularly or invest in new tools if yours cannot be sharpened.
  • Sterilize tools: During periods of high disease transmission, or after pruning an infected tree, sterilize your tools before beginning work on another tree. Pruning tools can easily pick up pathogens that cause tree disease; without proper sterilization, the disease will be passed to any other trees you prune with those tools.

WARNING: Avoid pruning during periods of high disease transmission. For many common tree diseases, this typically occurs when the weather gets warmer in the spring and summer. Consult with an arborist to plan the best time for pruning on your property.

Proper Mulching Keeps Your Trees Healthy

Mulching doesn’t just make your yard look nicer, it also keeps your tree healthier. A layer of organic mulch spread under a tree helps the tree by:

  • Retaining moisture in the soil
  • Limiting weed growth
  • Protecting roots
  • Decreasing foot traffic that compacts the soil
  • Reducing the risk of bark damage from landscape equipment

Spread a thin layer of mulch around your trees, around three inches deep, and ensure it doesn’t touch the trunk of your tree.

Biological Control Methods to Lower the Risk of Diseases

While some insects are harmful to your trees, others provide benefits for your landscape. Introducing beneficial insects onto your property, or protecting existing ones, can lower the risk of diseases. This is why we only recommend using chemical treatments as a last resort, as they can harm wildlife that benefits homeowners. Instead, we recommend working with nature to protect your trees.

Some friendly insects you might introduce include ladybugs, lacewings, and praying mantids. These insects are often predators of disease-spreading pests.

Mechanical Controls Can Limit the Chances of Pests Causing Diseases

Mechanical controls attempt to control pests and limit damage to trees without resorting to using insecticides. You can use traps or other methods to capture animals that may damage your trees and leave them more susceptible to infection. Netting and screens can help keep disease-carrying pests away from susceptible trees and shrubs.

Mechanical controls also involve physically removing insect pests from trees. Squash harmful insects wherever you see them (you may want to wear gloves for this). Or pick bugs off leaves and branches and drop them into a bucket or bowl of soapy water (they can’t escape from soapy water and will quickly drown). You can also shake bugs off leaves if you don’t want to touch them, as long as they fall into the water.

Pruning also falls under the umbrella of mechanical controls. Use proper pruning to:

  • increase airflow throughout the tree canopy (this helps prevent fungal diseases),
  • prevent branches from rubbing against each other and opening up wounds that could attract disease-carrying insects, or
  • remove diseased branches (don’t forget to dispose of them safely to avoid spreading the disease).

An arborist from Riverbend applying insecticides in a yard in Ar-lington, Virginia.

Chemical Treatments Should Be a Last Resort

While chemical treatments may be a last resort, they are also an important part of protecting your trees – but only if you properly apply them. That means getting the timing right, as well as the choice of chemical, dosage, and application method. Whenever possible, use organic or low-impact treatments to limit damage to the environment and the rest of your yard.

To ensure a safe application of disease treatments, hire an ISA Certified Arborist who has the experience, knowledge, and specialized equipment needed to properly apply any chemicals used.

Call Riverbend Tree Service to Help Prevent Tree Diseases

Preventing tree diseases is always preferable to trying to treat an infection once it has spread. By using a variety of simple preventive measures, you can keep your trees safe from disease and protect the investment you’ve made in them.

If you haven’t recently given your trees a checkup or are trying to deal with ongoing tree disease, the team at Riverbend Tree Service can help. Call us at 703-402-9366 or request an estimate online to set up an appointment with one of our arborists to diagnose any problems with your trees and get them looking beautiful once again.


Give Us a Call at 703-402-9366

If you'd like help with your trees or landscape, have any questions, or would like to schedule an appointment with one of our Certified Arborists, please give us a call. We'd love to hear from you!

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Peter Hart

Peter’s love of trees and the outdoors started early, becoming involved and teaching at Audubon nature camps at 12 years old. This appreciation for nature continued into adulthood as Peter earned his Arboriculture degree from the University of Massachusetts. From there Peter went onto become a Massachusetts certified arborist as well as earning an ISA Tree Risk Assessment Qualification.