Developing an Emerald Ash Borer Management Plan
for Townhomes & HOA’s
History and Background
After its discovery in 2002 in Michigan, Emerald ash borer (EAB) has killed millions of ash trees in a short time period. The Emerald ash borer is an exotic insect pest (non-native), so ash trees have no natural chemical or protection methods to fight off the insect. Unfortunately, EAB was found in Minnesota in 2009 and has already started to change our landscape. Most effective EAB management plans will involve the removal of ash trees, replacement of some ash trees, as well as treatment options to save valuable ash trees.
The damage and symptoms of an attack from Emerald ash borer can go unnoticed for 2-4 years before a tree starts to decline. Since prevention is the most effective management practice, a plan should be in place as soon as possible. Any ash tree within 15 miles of a confirmed Emerald ash borer site is potentially at risk.
Top 6 EAB Management Facts
- Regardless of your management plan, EAB is going to be costly for everyone.
- Untreated ash trees have virtually ZERO chance of survival
- In general, smaller-sized ash trees should be replaced, instead of treated.
- Not all ash trees should be saved.
- Chemical treatments are very effective against EAB.
- Treatments are more effective when preventively done.
Ash Removal & Replacement
As mentioned in Fact #4, not all ash trees should be saved. Any ash tree with poor structure or poor health should not be considered for chemical treatment, and should be identified as a possible future removal. Also, any ash tree in a poor location that provides minimal value should be removed. Many people feel that smaller ash trees should be replaced instead of being chemically treated.
There is no current evidence that ash trees can survive without chemical assistance. Ash trees have a much higher success rate of survival if EAB is prevented as compared to therapeutic treatments (treating infested trees). Also, healthier ash trees have a greater chance of survival over poor to moderately healthy trees. Trunk injections have slightly more effective results in controlling ash trees under heavy pressure.
- Soil application involves applying an insecticide directly into the soil surrounding the trunk. The insecticide is systemically distributed throughout the tree. There is a restriction with this application regarding the amount of chemical that can be applied to the soil per year so soil application may not be viable for all sites. There can be some concern on sites where surface runoff or leaching of chemical in the soil is possible. Soil applications will last for 1 growing season.
- Trunk injection involves directly injecting an insecticide into the trunk of an ash tree. With the trunk injection method, there is no chance of the chemical getting into the surface water through run-off and is generally considered a “safer” method. However, holes must be drilled into the trees. Trunk injections will last for 2 growing seasons.
Expected Timeline of EAB Attack
Assuming the rate of infestation follows similar patterns as previously devastated areas, the EAB attack will follow the general time line. Minnesota may have a different pattern due to colder winter and if early quarantines are successful.
- Emerald ash borer attacks initial trees
- Symptoms likely unnoticed
- Ash trees start to die on linear curve
- Damage and tree death commonplace, but seems like it is under control
- Ash trees start to die on exponential level
- Death and dieback of ash trees are beyond a controllable level
Year 12 and beyond
- Most untreated ash trees are dead (death rate hits peak and declines)
- Need for chemical treatment subsides in certain situations
12 Steps to Developing an Emerald Ash Borer Management Plan
- Analyze the short-term immediate threat (proximity to nearest EAB confirmed site)
- Analyze the long-term impact of losing ash trees
- Analyze the volume of ash trees
- Analyze the density of ash trees (a measure over 10% will have significant impact)
- Analyze the overall value of all ash trees on site (monetary, environmental, privacy, etc..)
- Assess woodland trees vs. “landscape trees”
- Provide an “Ash Tree Inventory” potentially with a GIS map of the site
- Measure the size of each ash tree
- Assess and rank the health of each ash tree
- Assess and rank the structure of each ash tree
- Assess and rank the location value for each ash tree
- Discuss and analyze all treatment options
- Assign monetary values for any potential removals, replacements or treatments
- Educate and inform all necessary parties (board members, homeowners, etc..)
- Identify any ash trees to be removed (immediate or future)
- Identify any ash trees to be replaced (immediate or future)
- Identify an ash to be chemically treated
- Decide on short and long-term budget issues
- Decide on timing of any removal, replacement or treatment
- Schedule any necessary monitoring, inspection and update of EAB Management Plan