UPDATE: Emerald Ash Borer (EAB) Infestation Spreading

New Emerald Ash Borer (EAB) Activity Outside Federal Quarantine Area

Federal quarantines have been trying their very hardest to stop the spread of Emerald Ash Borer and keep the destructive pest under control. Despite their best efforts, state and national officials have confirmed the spread of EAB to both Broomfield and Westminster, just north of Denver. 

According to the Colorado State Forest Service, five Colorado municipalities that are within the quarantine are now infested with the boring beetles. It is unclear if EAB was naturally or accidentally human-transported into new regions of Colorado. The new sightings of EAB have been outside the current quarantine area.

Six years ago the quarantine area was established, which primarily covers Boulder county. The quarantine was meant to help curb the spread of EAB by the human-transportation of wood, but there are now plans for a repeal. A formal process for repeal will begin this winter, largely because of the EAB’s natural ability to spread to new areas on its own. A second reason for the repeal is to give already infested communities within the area more options for disposing of removed trees.

Denver homeowners need to be prepared and take preventative measures to protect their trees. Learn urgent details about EAB and how you can take preventative action to protect your Ash trees now!

EAB Fast Facts 

  • The Emerald Ash Borer Beetle is a non-native wood-boring insect and first made its arrival in the U.S. in Michigan as part of an international shipment of wood from China. 
  • The EAB is now arguably the most destructive pest in the United States, killing all types of North American ash species, including autumn purple ash, a popular white ash varietal in Colorado.
  • In the larval stage, EAB cuts off the flow of water and nutrients to the tree by feeding under its bark. Once a tree falls victim to infestation, there is no saving it. Infested trees gradually die over approximately two to four years.
  • EAB does not move long distances naturally. They are known for being strong fliers, but EAB adults rarely fly less than half-a-mile from their emergence tree. 
  •  Humans moving ash firewood or ash nursery stock are thought to be responsible for the known cases of EAB moving long distances. For this reason, the movement of other untreated ash wood, wood chips greater than one inch, and ash products (green lumber, pallets, etc.) should be avoided at all costs.

EAB Tips for Front Range Residents

Due to the spread of EAB to new areas and plans for repeal on the quarantine, the Colorado State Forest Service offers these tips for Denver homeowners:

  • Determine now if you have any ash trees. Identifying features of ash trees include compound leaves with 5 to 9 leaflets; leaflets, buds, and branches growing directly opposite from one another; and diamond-shaped bark ridges on mature trees. More information about a related app for mobile devices is available here.
  • If you have an ash tree, start planning. Decide if the overall health of the tree merits current or future treatment or if it would be best to remove and replace it with a different species. If you aren’t sure, contact a certified arborist. If pesticide treatment is the preferred option, the applicator must be licensed by the Colorado Department of Agriculture as a Commercial Pesticide Applicator.
  • Recognize signs of EAB infestation. Property owners with ash trees should be on the lookout for thinning of leaves in the upper tree canopy, 1/8-inch D-shaped holes on the bark and vertical bark splitting with winding S-shaped tunnels underneath. Report suspect trees by calling the Colorado Department of Agriculture at 1-888-248-5535 or filling out their EAB Report Form.
  • Be aware of EAB imposters. Other insects like lilac/ash borer, ash bark beetle and flat-headed apple tree borer may look like EAB or cause similar tree symptoms. 
  • Help prevent further spread of EAB. Do not transport ash or any hardwood firewood, or any other untreated ash wood products, to other locations. Boulder County and some surrounding areas are still under a federal EAB quarantine, allowing for significant fines for those who move untreated wood from the area.

In the same way that healthy bodies can fight off infection, healthy trees that are well-watered and fed can defend themselves better from all types of insect infestation. We recommend feeding your ash trees to keep them healthy and give them a better chance of survival. At Fielding Tree & Shrub Care, we’ve developed a reliable plan of action for protecting trees from EAB. 

Preventative Treatment Options 

Start with preventative action that is safe and proven to work. There are options available to effectively treat ash trees threatened by EAB. These methods are field-tested and evaluated by university and government scientists and have a proven track record. 

It is best to begin treatment while ash trees are still relatively healthy. If treatment begins after the first signs of infestation, such as canopy thinning, it can stop additional damage, but it will not reverse any damage that has already been done. 

Protect Your Ash Trees, Know the EAB Warning Signs

One of the best things you can do to protect your trees is to learn the EAB warning signs. If you spot them on trees in your neighborhood or community, you can potentially save your trees before it is too late. Stay vigilant! Here are the warning signs:

  • EAB Adult Beetles and Larvae present
  • Broken branches towards the trunk of the tree
  • A dying canopy of leaves
  • D-shaped exit holes in ash tree bark
  • Bark splintering and S-Shaped Tunnels
  • Increased woodpecker interest or damage
  • Epicormic Shoots

Keep in mind that an infected tree may have only a few or any combination of these warning signs. Ash trees with minimal EAB larvae may even show no external symptoms of infestation!

I’ve spotted the EAB in my community, does that mean my tree will become infested? 

Most female EAB lay their eggs on nearby trees in a range of about 100 yards of the tree from where they originated, but some are now moving anywhere from half a mile to two or three miles! It is reasonable to assume that if your property is within 10-15 miles of a known EAB infestation, your ash trees are probably at risk. 

Don’t wait to take action. EAB is the most destructive forest pest in recorded U.S. history and is almost always fatal to infested ash trees. You need to take stock of your trees and make a plan to treat them before the EAB arrives, or they will be dead within approximately four years. 

Do I have any ash trees? What do I need to do as a property owner in Denver? Should I treat my ash tree? We are prepared to expertly help you answer all of these important questions. Protecting your trees is completely within your control. Get started by contacting one of our certified arborists at Fielding Tree & Shrub Care for a complimentary consultation. They can explain how EAB might personally affect your property, and go over all your customizable treatment and preventative care options.

Keep your ash trees safe and schedule your complimentary on-site inspection with Fielding Tree & Shrub Care today!