Emerald Ash Borer (EAB)

Here are some ways to prevent EAB infestations:

Recognizing the signs and symptoms early is crucial for effective management and treatment. This guide will help you identify EAB infestations, understand the progression of the disease, and explore available treatment options.

• D-shaped Exit Holes: One of the earliest and most definitive signs of EAB infestation is the presence of small, D-shaped exit holes in the bark of ash trees. These are created when adult beetles emerge from the tree.
• Bark Splitting: Infested trees often exhibit vertical splits in the bark. Beneath these splits, S-shaped galleries carved by larval feeding can be observed.
• Woodpecker Damage: Increased woodpecker activity is a secondary sign. Woodpeckers feed on EAB larvae, and their feeding leaves behind distinctive holes and patches of missing bark.

Advanced Symptoms

• Canopy Thinning: As the infestation progresses, the tree’s canopy will thin significantly, starting at the top and moving downward.
• Epicormic Sprouting: Trees often respond to EAB stress by producing new shoots or sprouts from the trunk and main branches.
• Dieback: Infested ash trees will experience branch dieback, with dead branches appearing throughout the canopy.

Diagnosing Emerald Ash Borer Infestations

Proper diagnosis involves both visual inspection and professional confirmation. Here’s how to diagnose an EAB infestation:

• Visual Inspection: Look for the signs mentioned above, especially D-shaped exit holes and bark splits. Use binoculars to inspect higher branches for canopy thinning and dieback.
• Professional Assessment: Contact a certified arborist or local forestry expert. They can perform a thorough inspection and may use tools like bark peeling to reveal larval galleries.
• Lab Testing: In some cases, samples may be sent to a laboratory for definitive confirmation through DNA analysis.

Rate of Disease Progression

The rate at which EAB infestations kill ash trees varies depending on several factors, including tree health, local EAB population density, and environmental conditions. Typically:

• Initial Infestation: Early stages might show minimal symptoms and can last 1-3 years.
• Active Infestation: Once significant larval feeding begins, trees can die within 3-5 years if untreated.
• Widespread Infestation: In areas with high EAB populations, ash tree mortality can exceed 99% within a decade.

Treatment Options

Preventive Measures

• Insecticide Treatments: Systemic insecticides, such as imidacloprid and emamectin benzoate, can be applied to protect ash trees from EAB. These are most effective when applied before trees show severe symptoms.
• Tree Health Maintenance: Keep ash trees healthy through regular watering, mulching, and avoiding mechanical injuries to the bark.

Reactive Treatments

• Chemical Control: Insecticides can still be used on infested trees if applied early enough. However, treatment effectiveness decreases as the infestation progresses.
• Biological Control: Researchers are exploring the use of natural predators and parasitoids that target EAB larvae. These biological controls show promise but are still under study.
• Removal and Replacement: Severely infested trees often need to be removed to prevent the spread of EAB to nearby healthy trees. Consider replacing removed ash trees with non-host species to diversify the urban forest.