Should I treat or remove my ash tree?
A healthy, valuable ash may be a candidate for long-term protection. A badly declining or structurally damaged ash may not recover. Confirm the species and condition before deciding. This is education, not a treatment offer. [1030]
Updated 2026-10-25
What a year of care looks like.
Most of the work happens below ground, in the soil the roots live in. Here it is, one step at a time.
A year of care, step by step.
Most of the work happens below ground, in the soil the roots live in. Press play, or pick a step.
Start at the soil line.
Two things we look for first: mulch piled against the trunk, and soil packed hard by mowers, cars and feet.
Uncover the root flare.
Compressed air blows the soil away without cutting roots. A root wrapping the trunk can be cut free, if that is safe for the tree.
Loosen packed soil.
We open channels in the packed soil with air and work in compost, so new roots have somewhere to grow.
Test before adding anything.
A soil test shows the pH and nutrients, and it decides what, if anything, the tree needs.
Add only what is short.
Many trees need no fertilizer at all. If the test shows a shortfall, we add only what is missing.
Mulch wide, water deep.
Two to four inches of mulch, as wide as you will allow, kept off the trunk. In dry spells, a slow, deep soak.
Come back every year.
We check the tree top to bottom once a year and leave a written report, so small changes get caught early.
Keep a sound tree when the evidence supports it. Do not promise to rescue a tree that is too far gone.
Confirm that it is an ash
Missouri's homeowner guide describes opposite buds and compound leaves with five to eleven leaflets. Identification comes before an emerald ash borer decision. A declining tree is not automatically an ash, and an ash is not diagnosed from leaf color alone. [1030]
Look at the whole tree
The state guide lists upper-crown thinning, new sprouts, increased woodpecker activity and D-shaped exit holes among possible signs. Ask for an assessment of the crown, trunk and growing site. Do not peel bark or approach unstable limbs just to gather a photograph. [1030]
Protection is a continuing commitment
Missouri's guide explains that insecticide protection requires repeated treatments over many years. It considers vigor, crown loss, significance and site suitability when comparing options. An otherwise healthy shade tree has a different outlook from a severely injured tree in a poor location. We are describing the state's decision framework, not offering applications. [1030]
When removal becomes the stronger option
The state guide says trees with more than half their crown in dieback, severe injuries or many borer attacks are unlikely to recover. That screening guidance is not a guarantee that every tree below that threshold can be retained safely. Have the structure assessed before deciding. If removal is appropriate, plan the work before the tree deteriorates further. [1030]
Check public ownership and keep wood local
For an ash near a street, confirm ownership and city plans before arranging treatment or removal. Missouri's guide specifically advises checking with the city for street-adjacent trees. It also recommends local disposal to reduce accidental pest spread. [1030] Private work on a St. Louis City Tree requires Forestry's permit process. [1002]
What this page does not offer
This page does not advertise pesticide application or promise treatment results. Ask a properly authorized provider about treatment suitability and current requirements. Our request flow can start with a tree check. It does not book an emerald ash borer application.
Questions about this work
Is treatment always better than removal?
No. Tree condition, structural damage, site and the commitment to ongoing protection all matter. The state guide recommends removal and replacement for some low-value or severely declining trees. [1030]