Green Ash Trees: Food for Borers

(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.

August is Tree Check Month: Are Your Trees Safe?

In case you haven’t heard, August is Tree Check Month and taking a few minutes from your day to examine your trees for pest threats could save you some grim damage down the road. August is a time of peak emergence for the Asian longhorned beetle (ALB) who earned a reputation for threatening recreational areas, forests and suburban shade trees. If ALB were to become widely established in the U.S., it would have a severe impact on the timber, maple syrup, tree nursery and tourism industries and would take decades to recover.

ALB

Spot the Signs

Besides seeing the beetle itself there are distinctive signs to look for while examining your trees.

  • Round Exit Holes– adult beetles chew their way out of the tree, leaving one-quarter inch exit holes.
  • Oval or round-shaped egg sites- female beetles chew up to 90 oval depressions, called oviposition sites, or egg sites, into the bark of the host tree, and then lay a single egg beneath the bark resembling a wound on the tree.
  • Accumulation of frass- As the larvae feed they leave a sawdust-like excrement on the ground or branches.
  • Weeping sap- Tree sap may be seen from the wounds or egg sites left by the beetle.
  • Tunneling- Larva tunnel through the layers of the tree.
  • Pupal chambers- beetle larvae inside the tree will develop (pupate) in a chamber or area in the tree, turning into adult.
  • Unreasonable yellowing or dropping of leaves- If you see leaves turning colors sooner than they should be, or broken, dead, or dying branches, this can be a sign that something is wrong.

Trees at risk

Read up on last year’s blog post August is Tree Check Month: Is your tree safe from Asian Long-horned Beetle? to learn more about ALB. ALB isn’t the only pest you should watch out for, check out Six Pests You Should Know About to stay proactive in your tree’s health.

Report It

If you think you’ve spotted signs of damage from ALB contact your state ALB eradication program office or plant health director’s office.