Can You Treat Ash Trees Yourself?

Start by understanding that treating ash trees yourself is possible for some problems, but the deadly emerald ash borer (EAB) often requires professional help. Smaller trees under 15 inches in diameter can be treated with homeowner products, but large, infested trees need certified arborists. This guide covers what you can handle on your own and when it's smarter to call an expert.

What Are the Common Problems With Ash Trees?

Ash trees face several pests and diseases. You should learn the most common ones before deciding on treatment.

• Emerald ash borer (EAB) – A metallic green beetle that kills trees within a few years. The larvae tunnel under the bark, cutting off water and nutrients.
• Ash yellows – A disease caused by a phytoplasma that stunts growth and yellows leaves. There is no cure.
• Ash anthracnose – A fungal disease that causes brown leaf spots and early leaf drop. Usually not fatal.
• Ash leaf rust – Orange or yellow spots on leaves. Most trees survive without treatment.
• Verticillium wilt – A soil fungus that causes wilting and branch death. No chemical cure exists.

Most homeowners worry about EAB, and that's the focus of this article. Other problems like anthracnose or leaf rust are rarely worth treating yourself unless the tree is small and valuable.

How Do You Know If Your Ash Tree Has Emerald Ash Borer?

You cannot treat what you have not identified. Look for these signs of EAB infestation:

• D-shaped exit holes about 1/8 inch wide in the bark. These are adult beetles leaving the tree.
• S-shaped tunnels under the bark (called galleries). Peel back a small piece of outer bark to see them.
• Thinning canopy starting at the top of the tree. Branches die back gradually.
• Woodpecker damage. Woodpeckers eat EAB larvae and leave patches of missing bark.
• Epicormic shoots (also called water sprouts) growing from the trunk or main branches.

If you see any of these symptoms, you need to act fast. Treating your ash tree yourself is only possible before the infestation is severe. Once more than 30% of the canopy is dead, professional treatment or removal is usually necessary.

Can You Treat Ash Borer Yourself?

The answer depends on your tree's size and the stage of infestation. For small ash trees (under 15 inches trunk diameter) that are still healthy, you can treat them yourself using soil drench or trunk spray products. The most common DIY treatment uses a systemic insecticide containing imidacloprid. You mix it with water and pour it around the base of the tree. The tree absorbs the chemical into its sap, killing EAB larvae when they feed. To do it right:

• Measure your tree's trunk diameter at chest height.
• Apply the correct dose according to the product label. Underdosing wastes money and can lead to resistance.
• Apply in spring or early fall (April to May or September to October) when soil is moist.
• Water the area well after application to move the chemical into the root zone.

For larger trees, you need more powerful products like emamectin benzoate, which is usually injected into the trunk. Trunk injections are best left to professionals because they require precise drilling and dosing. Mistakes can damage the tree. If you decide to try a soil drench, consider a ready-to-use imidacloprid product designed for ash trees. Follow all safety precautions – wear gloves and keep pets away from the treated area.

What Treatments Work for Other Ash Tree Diseases?

For diseases like ash anthracnose or leaf rust, treatment is rarely needed. Healthy trees recover on their own. You can help by:

• Raking and disposing of fallen leaves to reduce fungal spores.
• Watering during dry spells to reduce stress.
• Avoiding overhead irrigation that wets leaves.

For ash yellows or Verticillium wilt, there is no cure. Remove severely infected trees to prevent spread. Do not compost the wood. If your tree has mechanical damage from storms or lawn equipment, you can treat small wounds yourself. Use a clean pruning saw to remove torn bark. Do not apply tree wound dressing – it actually traps moisture and promotes decay. Let the wound heal naturally. For pruning, use sharp tools. A good quality pruning saw makes clean cuts that heal faster.

What Tools and Products Do You Need for DIY Ash Tree Care?

If you plan to treat your ash tree yourself, gather these items: For safety, always read product labels. Wear chemical-resistant gloves when handling insecticides. Keep children and pets away until the treated area is dry.

When Should You Call a Professional Instead?

DIY treatment works best for prevention. If your tree already shows clear signs of infestation, a professional may be your only chance. Call an arborist if:

• Your tree's trunk diameter is over 15 inches.
• More than 30% of the canopy is dead.
• You see multiple D-shaped exit holes on the trunk.
• The tree is near your house, driveway, or power lines (a falling tree is dangerous).
• You are unsure about the correct chemical or dosage.

Professionals use emamectin benzoate injections that protect for up to two years. One injection costs $10–$20 per inch of trunk diameter. For a 20-inch tree, that's $200–$400. Compare that to a few years of soil drenching at $30–$50 per year for smaller trees. Also, some areas have quarantines for ash wood. Check with your local extension office before moving firewood or pruning debris.

A Simple DIY Ash Tree Treatment Checklist

Use this quick list to decide if you can treat your ash tree yourself:

• Tree trunk diameter under 15 inches? Yes → Continue. No → Call an arborist.
• Less than 30% canopy dieback? Yes → Continue. No → Call an arborist.
• You have the right insecticide and protective gear? Yes → Continue. No → Buy supplies first.
• You know the correct dosage from the product label? Yes → Continue. No → Read label carefully.
• You can apply during spring or early fall when soil is moist? Yes → Go ahead. No → Wait for the right season.

If you answer "yes" to all, you can safely treat your ash tree yourself. If any answer is "no," hire a professional.

How Often Should You Treat Your Ash Tree?

For EAB prevention with a soil drench of imidacloprid, you need to treat every 1 to 2 years depending on product strength and infestation pressure. Read your product label for specific intervals. For trunk injections by a professional, treatments last 2 to 3 years with emamectin benzoate. Re-treat before the protection runs out. Do not skip years because the tree can become reinfested quickly. If you live in an area with active EAB (most of the eastern and central U.S.), start treatment as soon as borers are confirmed within 10 to 15 miles of your yard. Prevention is cheaper and easier than saving a heavily infested tree.

What Happens If You Don't Treat an Ash Tree With EAB?

Without treatment, an ash tree infested with emerald ash borer will die within 2 to 4 years. The beetles spread quickly from tree to tree. A dead ash tree becomes brittle and can fall suddenly, damaging property or hurting people. If you decide not to treat, consider having the tree removed while it is still alive (green wood is easier and safer to remove). Dead ash trees often require more expensive crane or bucket truck work. Removing a small ash tree yourself is possible with a chainsaw and proper safety gear. But for trees over 20 feet tall, hire a professional removal company. Falling limbs and trunks can kill.

Can You Save an Ash Tree That Has Started Dying?

Yes, but only if the damage is caught early. If less than half the canopy is dead, a professional can sometimes save the tree with intense treatment. For DIY, it is not realistic. Once EAB larvae have girdled the trunk, water flow is cut off and the tree cannot recover. If you want to try, the only option is trunk injection by an arborist. Soil drenches work too slowly for a dying tree. Annual retreatment will likely be needed. For trees that are more than 50% dead, removal is the only safe choice. Plant a different species nearby (like oak, maple, or linden) so you don't lose shade in your yard.

Is It Worth Treating Ash Trees Yourself?

For small, healthy trees in areas with low to moderate EAB pressure, yes – DIY treatment is cost-effective and practical. You save the cost of professional visits. You can apply the treatment in one afternoon. But you must be consistent. Missing a year of treatment can allow beetles to get established. Once they are inside the tree, them you. DIY treatment works best as prevention, not rescue. If you have a large, mature ash tree that provides important shade, hiring a professional is money well spent. The cost of removal later is much higher than the cost of treatment. Finally, check with your local Cooperative Extension Service. Many offer free advice on ash tree care and may have bulk treatment programs for your neighborhood.

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