America's Ash Trees Are Being Wiped Out—Here's How You Can Help Them

Photo: MightyJoePie/Flickr

America’s Ash trees are facing extinction. And the impact of their loss in our forests, cities, and backyards will not be small.

The United States’ eight billion ash trees, which live in every state with high concentrations east of Colorado and along the Pacific Northwest coast, are threatened by the Emerald Ash Borer, a beetle native to Russia and China that was likely brought here on ships in the mid-1990s. By the time the Borers were discovered in 2002, it was too late to stop them. Researchers are calling the beetle the most serious threat to forests ever seen in the US. Millions of trees across the Midwest are already dead, and today, the Borers are spreading quickly across the Northeast.


However, at a Saving the American Ash summit at The New York Botanical Garden last week, researchers said there is hope, at least of preventing the Ash’s complete annihilation. Homeowners, citizen scientists, and anyone concerned about the fate of one of our country’s most ubiquitous trees can help.

Map of the current Emerald Ash Borer infestation. Image: USDA

Before the Borers Arrive

There are a series of steps you can take that will help slow the spread of the infestation, protect some Ash trees from dying, and preserve their genetic material for replanting. The first step is to learn how to identify an Ash. Every species is susceptible to infection. You can easily spot them once you learn the unique characteristics of their bark, leaves, and branch patterns.

Ash tree pods. Photo Courtesy The New York Botanical Garden

Next, take a survey of your land, your neighborhood, or even public parks in your area. If you want to do some serious citizen science, you can find a stand of Ash trees and create a monitoring plot a half-acre in size that contains at least 40 trees that are a minimum of 10 centimeters in diameter. By visiting and monitoring your plot a few times a year, you’ll be helping the scientists tasked with identifying healthy Ash trees, tracking the onset of infestation, and most importantly, discovering survivors once the beetles have moved on. If you live in the Northeast, you can participate directly in Ash tree infestation research here.


Now that you’ve ID’d your local Ash trees, you have to decide what to do with them. Scientists think the Borers will eventually arrive, which means it’s important to choose some trees you’d like to save. “If you’re emotionally attached to it or it has a swing hanging from it,” then the tree can be injected with insecticide, Jonathan Rosenthal, director of the Ecological Research Institute, said at the summit. This is a costly operation and has to be done at least once a year by an expert.

You can also collect seeds from healthy trees that are naturally occurring, meaning they are genetically unique to your area. This will help with repopulation and replanting of Ash trees once the beetles have left. The US National Arboretum and other sites around the country are accepting seed donations.

Photo Courtesy The New York Botanical Garden

Identifying and removing any invasive species from the understory of your Ash trees will also help ensure that their death doesn’t create a whole different kind of ecological disaster. Some of the most common invasive species in the US are plants like English Ivy and Japanese Honeysuckle. If your Ash trees are shading invasive species, yank them out and replace them with native plants, which will also help support your local bird population.


Be careful when working around Ash trees—borers start to infest from the top down. That means branches could be unstable even if the tree looks healthy at the bottom of the trunk.

And above all else, do not cut down stands of Ash trees in the hopes of stopping or slowing the spread of Borers. The beetles can fly up to 20 miles. If they don’t find any Ash trees in one region, they’ll just keep flying until they spot their next victim. Cutting down healthy Ash trees has actually be shown to speed the spread of the Borers, according to Kathleen Knight, a research ecologist at the USDA Forest Service who spoke at the summit.


Once you’ve identified trees, set up a monitoring plot, collected seeds, and dealt with any invasive species, all that’s left to do is watch and wait for the infestation to begin.

After the Infestation Begins

The Borer kills Ash trees by laying eggs under the bark, where larvae then chew through the inside of the tree and effectively suffocate it. Infected trees will start to lose their canopy and attract woodpeckers, who love eating Borer larvae. They can lose a third to half of their branches in a single year, and they will feature distinct D-shaped holes where adult Borers leave the trees at maturity, around June.

This Oct. 26, 2011 photo shows markings from emerald ash borer left on an Ash tree in New York. Photo: AP

When you start seeing these signs of infestation you can report them to your local authorities here. Cut down any hazardous trees that are dead or nearly dead before they do harm to people or buildings.


Even after the majority of Ash trees in your area are dead, you can still help. Ecologists at the Forest Service are currently trying to find Ash that managed to survive infestation and may hold clues to genes that boost immunity to the beetles. Called “lingering Ash,” these trees will have a completely healthy crown, are untreated by insecticide, are naturally occurring, and have survived 95% Ash tree mortality events in your area for at least two years. Identifying lingering Ash has only been done by scientists in the Midwest, according to Rosenthal, so reporting these trees to your local USDA offices is a big help to researchers.

A horticulturalist from the Agriculture Research Service in Ames, Iowa examines Ash tree seeds as part of an effort to preserve the trees for after the infestation has passed. Photo: AP

Unfortunately, right now it doesn’t look like the beetle’s reign of terror can be stopped. In addition to looking at tree genetics, researchers are studying small wasps that prey on Ash Beetles, and testing the cold-temperature tolerance of beetle larvae. If America assumes all-hands-on deck to help scientists better understand the problem, we might figure out an intervention. And if we don’t, at least we can slow the Emerald Ash Borers down, and preserve some seeds for future generations.

Erin Biba is a freelance journalist focused on how science and technology intersect with climate, the environment, and human health.


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