Emerald Ash Borer

The Emerald Ash Borer is a pest that is Federally regulated. Native to Asia, this borer was first identified in Michigan in 2002; since then it has killed millions of ash in 32 states, and Colorado has not escaped the plague. (Photo: Shutterstock)

 

Carol O'Meara, Colorado State University Extension

Carol O’Meara, Colorado State University Extension

LONGMONT – It takes a lot to rouse a Lorax, but when trees are threatened, those who speak for the them get moving.  And when that threat is a pest so destructive the Federal Government wants it gone, Loraxes near and far become an army to try and stop it.

The Emerald Ash Borer is a pest that is Federally regulated.  Native to Asia, this borer was first identified in Michigan in 2002; since then it has killed millions of ash in 32 states, and Colorado has not escaped the plague. Unfortunately, it has now been found in Boulder, Longmont, Lafayette, Gunbarrel and Lyons.

It took a human to bring it here, likely in firewood or nursery stock.  To prevent its spread, Boulder County is quarantined since 2013.  The small, half-inch long beetle is a brilliant emerald green, with no stripes or dots. When its wings unfold, they reveal a deep purple body. Adults fly from early May into September, laying eggs on ash tree trunks. Once they’ve hatched, the white larvae tunnel under the bark, where they zigzag around, eating the wood and growing larger. Their tunnels cut off the flow of water and nutrients; each year more tunnels seal the fate of the tree, killing it in three to four years.

Once infested, little stops the bug. Treatments slow its attack, but eventually the tree succumbs.  Ashes of all sizes are attacked; the Emerald Ash Borer doesn’t care if it’s a sapling or stately old tree.  All species of ash (Fraxinus spp.), white, purple, green, and their cultivars are at risk, but mountain ash is not a target, since it isn’t a true ash.

In Colorado, it’s tough to be a tree. Drought, compacted soils, and other insect borers give our ash a rough time. Learn the symptoms of an Emerald Ash Borer attack, such as thinning of the canopy, sucker growth from the base or lower trunk, splitting bark, D-shaped exit holes, or woodpecker damage. When trees have several of these symptoms, ask an arborist to come check it out.

Because ash trees become brittle after they succumb to the bug, the trees can pose a hazard, so make a plan for your ash if you have one.  Options include doing nothing, removing and replacing the ash with a different tree species, or treating the tree with pesticides.  Should you live outside the quarantine, you needn’t spend the money on treatments.

Along roadways, Boulder County is flagging ash trees for removal to prevent them from becoming a hazard to drivers.  Should you spot one of the orange-wrapped trees, this is a tree scheduled for removal. But citizens can adopt the tree and prevent its removal; adoption means you take responsibility for treating the tree so it doesn’t succumb to the insect. For more information on the Adopt an Ash program, visit bouldercounty.org/property-and-land/forest-health/emerald-ash-borer/#what-we-are-doing.

Because Boulder County is quarantined, no ash wood can move out of our county unless it is treated by chipping to one-inch by one-inch pieces, being composted, or is heat treated in a kiln. Live trees cannot be moved out of the county.

Check with your city for guidance on laws that might affect your decision, such as removal of dead trees should they pose a safety hazard. Check out the Colorado Department of Agriculture website for information on the insect, the plan, and options for protecting your tree colorado.gov/agplants/emerald-ash-borer.

By Carol O’Meara, Colorado State University Extension. CSU Extension together with Boulder County Parks and Open Space, provides unbiased, research-based information about consumer and family issues, horticulture, natural resources, agriculture and 4-H youth development. For more information contact Colorado State University Extension at the Boulder County Fairgrounds, 9595 Nelson Rd., Box B, Longmont, 303.678.6238, e-mail comeara@bouldercounty.org or visit ext.colostate.edu/boulder.