If you have an ash tree that's dying or was just taken down because of emerald ash borer, the wood inside is often still good lumber, but it doesn't stay that way. Dead ash dries out, cracks and turns brittle as it stands, and the longer it waits, the less usable wood is left. Get the tree down safely by a tree service, keep the trunk in long sections, and get it to a mill soon.
Ash is a good hardwood. It's strong, light-colored, straight-grained and easy to work. White ash is the traditional wood for tool handles and baseball bats. A borer-killed tree doesn't have to become firewood.
What emerald ash borer does
Emerald ash borer is a small, metallic green beetle from Asia. The Missouri Department of Conservation says it attacks all species of ash and kills more than 99 percent of the trees it attacks (MDC). MDC reported it in 89 counties and the City of St. Louis as of 2021.
The larvae feed just under the bark, in the thin living layer that carries water and nutrients up and down the tree. When enough of that layer is destroyed, the tree starves. According to MDC, ash trees typically show declining health for 2 to 4 years before the borer kills them.
Signs MDC lists include woodpecker damage, sprouts growing from the main trunk and major branch loss. Woodpeckers peeling away bark to reach the larvae leave light-colored patches on the trunk, often the first thing people notice in winter.
Why the wood inside is often still good
Because the larvae feed in that layer just under the bark, a tree that has recently died or is still declining often has sound wood inside. The galleries show on the outer surface of the log and get removed with the bark and the first slabs.
What hurts the lumber is time after death:
- Drying and checking. A dead tree stops moving water. The trunk dries out while it's standing, and the wood shrinks and cracks. Those checks run into the boards.
- Brittleness. MDC warns that dying or dead ash become very brittle (MDC). Brittle wood breaks when the tree comes down, which shortens or splinters the logs.
- Stain and decay. Fungi move into dead sapwood, and ash has a wide band of pale sapwood. Gray and blue stain spreads first; rot follows.
- Other insects. Wood borers and beetles move into dead and dying trees.
So the answer to "can I mill my dead ash?" depends on how long it's been dead and how it's been sitting. A tree removed while still partly alive, or shortly after it died, usually mills well. A tree that has stood dead for years, or a trunk that's been lying on the ground, often has more checks, stain and rot than good wood. Send us photos of the cut ends and we'll tell you which you have.
Safety first: dead ash is dangerous
Brittle dead ash can drop limbs or snap without warning. MDC advises that dying or dead ash should be removed promptly if they pose a threat to people or property. This is work for a professional tree service, not a homeowner with a chainsaw.
We don't cut trees down. Have a tree service remove the tree, and tell them before they start that you want to keep the trunk. Dead ash can't always come down in long sections safely, and the crew decides that. Our guide on what to tell the tree crew covers what to ask for.
How to handle an ash log
Keep it long and straight. Eight, 10 and 12 feet are the useful board lengths. Ash often grows tall and straight, so a good trunk can give several logs.
Get it off the ground and seal the ends. Ash sapwood stains quickly once the log is cut, especially in warm weather. Get logs up on cross pieces and coat the end grain with a wax-based log sealer. See how to cut and store a log.
Keep it local. MDC says the borer can emerge from ash firewood and logs for up to two years after harvest, and asks that felled ash be disposed of locally (MDC). Don't haul ash logs or firewood long distances. A log going from a Columbia-area yard to a Columbia-area mill is a short, local trip. If you're bringing ash from farther away, ask us first.
Getting the log to us
What ash lumber is good for
Ash saws cleanly and dries fairly easily compared with oak. It's a ring-porous wood with grain similar to oak, light cream to tan in color, and it takes stain well. Common uses:
- Furniture, tables and chairs
- Cabinets, shelving and trim
- Tool handles and other parts that need strength and shock resistance
- Flooring
- Bench tops and workbenches
Ash is not rot-resistant. Keep it indoors or well protected from weather. It's a poor choice for trailer decks, fence boards or anything in ground contact.
Drying your ash boards
Ash boards need to be stickered and stacked the day they're sawn. Sapwood stain moves fast in wet ash, and boards piled flat without spacers can turn gray in warm weather. Follow MU Extension's air-drying setup, summarized in the stickering section of our rough-sawn lumber guide.
A common rule of thumb is roughly a year of air drying per inch of thickness, though season and weather change that a lot. Air-dried lumber in Missouri typically levels off around 12 to 14 percent moisture content, while wood used indoors in Missouri runs about 6 to 10 percent (MU Extension G5507). Air-dried ash is ready for outbuildings and shop projects. For indoor furniture, it needs further drying to match the inside of a house, or it will keep shrinking after you build with it.
A word on ash species
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Ash tree down or coming down? Send us photos of the cut ends, the trunk, and the diameter and length, and tell us roughly when it died. We'll tell you how much good wood is likely left and what milling it will cost.