Tree Care Tree of the Week

Green Ash Trees: Food for Borers

By Sheereen Othman | October 7, 2015

(Fraxinus Pennslyvania)

green-ash-1070Green Ash trees are popular because of their durability and tolerance to a wide range of climates (growing anywhere in hardiness zones 2-9). They are great shade trees growing up to 60 feet at maturity and have a wide canopy. Despite being a hardy tree, the green ash has become victim to one of the most invasive insects in American History: the Emerald Ash Borer (EAB).

The tree grew in popularity after the onset of Dutch elm disease and was heavily used as a replacement for the American elm. With a shift in evolving tree pests, the green ash is now one of the most susceptible trees to the infestation. EAB beetles feed on the inner bark of ash trees, disrupting the tree’s ability to transport water and nutrients. EAB has killed tens of millions of ash trees in southeastern Michigan alone, with millions more under threat throughout the east coast and Midwest.

If you have an ash tree and live in a state where it is detected, you may have already lost it to EAB. If however your ash tree is still standing, then there are different insecticide options to protecting your trees in the fight against the Emerald Ash Borer.

  • Apply insecticides to your trees if you are within 10-15 miles of an EAB outbreak. Insecticides against EAB have progressed since the first outbreak in 2002 and are better than their earlier counterparts and less costly than removing trees altogether. However, this is a proactive measure in applying it to trees before they are infested.
  • If your trees are already infested insecticide will prevent further damage, but it will not reverse what has already been done.
  • There are different application methods of applying insecticides to ash trees, and it is a measure that will need to be continuously done for several years to ensure EAB doesn’t infest them.
  • Trees displaying more than 50% of canopy loss are less likely to recover even if treated with a highly effective insecticide.

figure-emerald-ash-borer-1[1]As important as it is to treat and care for your ash trees before they are infested, starting too early can be ineffective and a waste of money. If you are more than 10-15 miles of an EAB outbreak then it is probably too early to begin insecticide treatments. Stay up to date on the latest EAB infestations with quarantine maps. Learn more about the signs and symptoms of EAB by visiting emeraldashborer.info.

Despite the threat of EAB, ash trees are a wonderful species of trees. Their lush canopy provide shade in the summer heat and vibrant foliage in the fall.

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