The emerald ash borer (Agrilus planipennis) has hit Ontario hard. Named for its brilliant green carapace, this little insect has made itself at home in our northern hardwoods that remind it of the mountainous Asian forests where it originated. The difference between Ontario and Asia, however, is an absence of natural predators here that keep this tree-eater in check. Learn how to inspect your ash for emerald ash borer damage, and why it is important to get a close look at the canopy.
Insects
The most obvious way to determine if emerald ash borers are infecting your tree is to search for the insects themselves. Look for a small, iridescent green beetle about 1 centimetre long and 3 millimetres wide. If you are lucky, you may catch sight of an adult as they emerge from the trees in May, or see one crawling on a warm sunny day in June as they look for mates on the tree trunks. Starting in June, also look for the tiny red-brown eggs in cracks and crevices along the bark.
Don’t give your tree a clean bill of health just because you don’t immediately see any insects. While insects caught in the act of destroying your tree are indisputable symptoms of an infestation, finding them is easier said than done. The insects are comparable in size to a staple and the eggs are well-camouflaged on the tree bark. They do not swarm in large groups, so finding one is like a needle in the haystack of twigs and branches.
Leaf and Bark Damage
If you don’t find the beetles themselves, search for clues they have left behind. The first place to look is in the canopy, where you might see skeletonized leaves that adults have eaten. Next, look closely at the bark for tiny holes shaped like an upside-down loaf of bread. Also, take note of any light-coloured areas that stand out against the otherwise dark tree trunk. These pale sections can be indicative of woodpeckers feasting on EAB larvae in the inner layers of bark.
When an infestation is extensive or has been going on for several years, the signs can be obvious. However, by this time it is often too late to save the tree. An EAB infestation is comparable to a cancer that grows unnoticed on the inside, not causing symptoms until it is well advanced. This is because the most serious damage is inflicted by the beetle larvae, who destroy the tree’s ability to transport water and nutrients.
Branch Fractures
The best way to inspect for EAB damage is to search the upper canopy for fractured branches. These splits occur when larvae damage the tree’s circulatory system to the point that it cannot effectively transport nutrients into the canopy. They are most obvious in areas close to where the trunk meets the stems, especially in the first scaffold branches.
In a published scientific study, investigators determined that a majority of infested ash trees they looked at did not have the usual signs of bark and canopy loss, holes in the trunk, or visible adults or eggs. However, almost all of them did show fractures in the upper canopy. Researchers also found that treating the trees with pesticides before they lost 30% of their canopies helped most of them to recover; after that time, survival declined even after treatment.
Martin’s Tree Service
The professionals at Martin’s Tree Service have received training in the most up-to-date methods of searching for and eliminating the emerald ash borer from your ash trees. Our technicians can inspect the upper canopy for hard-to-see damage. Responding to early signs of infestation can mean the difference between a tree surviving or slowly dying over the next several years. Call us today to request a quote.
Steve Martin
