Yanez Tree Service Experts is calling attention to published guidance from University of Maryland Extension indicating that ash trees killed by emerald ash borer become unsafe to climb within roughly six months of dying, a timeframe that narrows the options for removing them. The company raised the point as storm season continues across Maryland, when standing dead trees are most likely to fail.
Extension advises that ash killed by emerald ash borer becomes brittle, and that tree care companies will not climb an ash that has been dead for more than six months. The same guidance recommends that dead ash trees located in yards, near buildings or along streets be removed promptly rather than left standing.
The distinction matters because it changes how the work is carried out. A tree that can still be climbed can be taken down by a crew working from within the canopy, using rigging attached to the tree itself to control each section as it comes down. Once the wood has become brittle, that approach is no longer considered safe, because the limbs and unions the rigging depends on can no longer be relied on to hold load. Removal then requires equipment reaching the tree from the ground or an aerial lift, which depends on whether there is access to get that equipment close enough.
"The six month figure surprises people, because a dead tree looks the same in year two as it did in month three," said Alejandro Yanez, owner of Yanez Tree Service Experts. "The difference is in the wood. Sound wood bends under load. Brittle wood lets go without warning, and that changes what can be done safely."
Emerald ash borer is a wood boring beetle native to Asia, first detected in North America near Detroit, Michigan in 2002. The larvae feed in the tissue just beneath the bark, disrupting the movement of water and nutrients and eventually killing the tree. According to the Maryland Department of Agriculture, the insect has been found throughout Maryland, and the federal domestic quarantine regulating the movement of ash material was lifted in January 2021 after the infestation became too widespread for containment to remain practical.
Extension notes that ash represent a small share of the trees in Maryland yards and forests, but are common along roadsides, in hedgerows and in disturbed areas where they seeded in without being planted. That distribution is part of why dead ash so often ends up near something it can damage. Municipalities across the region have addressed the problem directly. The City of Gaithersburg maintains a public information page on emerald ash borer, and jurisdictions statewide have removed dead and dying ash from parks and rights of way.
Extension describes several signs that an ash is affected. Thinning begins in the upper canopy and works downward, sprouts may appear along the trunk and base as the tree attempts to compensate, and woodpecker activity often increases as birds strip bark to reach larvae underneath. Bark may separate from the trunk in patches, exposing the winding galleries the larvae leave behind, and small D shaped exit holes may be visible where adult beetles have emerged. Extension also notes that an ash can be infested for several years before symptoms become obvious from the ground, which is part of why the timeline for a given tree is hard to judge by appearance alone.
For property owners, the practical consequence is a sequence rather than a single decision. Where limbs have died within the canopy of a tree still standing sound, deadwood removal addresses the falling hazard those limbs present without taking the tree down. Where the tree itself has died, Extension's guidance points toward removal, with the method depending on how long it has been dead and what surrounds it. Stump grinding follows removal and returns the area to use.
Yanez Tree Service Experts also pointed to long standing state and federal guidance on firewood. Extension advises against transporting firewood and recommends buying it where it will be burned, because moving cut wood is one of the primary ways wood boring insects reach areas they have not yet infested. That guidance applies to wood generated by removals as well as firewood bought for household use.
"Ash makes good firewood, and people do not want to waste it," Yanez said. "The guidance is not to stop using it. It is to keep it local, and to burn it where it was cut rather than moving it somewhere new."
The Maryland Department of Agriculture and University of Maryland Extension both maintain public resources describing emerald ash borer, the signs of infestation and current guidance for property owners with ash trees.
Yanez Tree Service Experts is a family operated tree service company providing tree removal, tree trimming and pruning, deadwood removal, stump grinding, land clearing, and cabling and bracing for residential and commercial properties in Montgomery County, Maryland.
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For more information about Yanez Tree Service Experts, contact the company here:
Yanez Tree Service Experts
Alejandro Yanez
(301) 503-9806
alejandroy24@gmail.com
886 College Pkwy, Rockville, MD 20850