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The Newest Threat to Maryland Forests


One of the largest threats to the lush and diverse Maryland forests isn’t deforestation or wildlife population changes—it’s the emerald ash borer. The emerald ash borer has destroyed countless ash trees throughout the United States. They are a serious and urgent threat to forests and cause an estimated billions of dollars’ worth of damage every year.

The Same Thing Happened to Chestnut and Elm Trees

Invasive pests are unfortunately nothing new for Marylanders. The American chestnut tree suffered tremendous losses during the 1900s due to a fungus infestation that rapidly spread throughout the country. A whopping 4 billion American chestnuts, or 25% of the total hardwood tree population in the country, were lost as a result of the invasive fungus. The same thing happened to American elms in the mid-20th century as a result of a small beetle that spread Dutch elm disease.

The Emerald Ash Borer

The emerald ash borer is a small green beetle that came to the United States from Asia. They bore holes in ash trees and show almost no sign of stopping. They are a particular threat to cities, where many ash trees were planted to replace the American elms killed by Dutch elm disease. Trees that are suffering from the emerald ash borer have a dying upper canopy, new growth at the bottom, D-shaped holes in the trunk and increased woodpecker activity. After a few months of infestation, affected ash trees are not safe to climb and will need to be removed or treated right away.

Stopping the Devastating Impact of the Emerald Ash Borer

Stopping the spread of the emerald ash borer cannot be done with a single technique or strategy. However, by focusing on the prevention of the next pest and treating existing trees, the impact can be reduced.

  • Plant diverse trees in forests and urban areas. Planting a single type of tree can lead to widespread damage in the event of a pest that targets that species.
  • Inject pesticides into ash trees on your property to protect them from infestation. This has a 100% success rate in terms of stopping the emerald ash borer. Treatment costs about $250 a tree every two years, while removal can cost between $700-$1,200.
  • Purchase your firewood locally to prevent purchasing wood with emerald ash borers living in the bark.
  • Visually inspect your trees regularly.
  • Work with pest control specialists to treat ash trees in your yard.

If you suspect you might have a problem with emerald ash borers, contact a tree company, such as Bartlett Tree Experts, to come out and assess issue.