Knowledgebase
ash tree with borer #889754
Asked November 12, 2024, 9:32 PM EST
Hello, I Moved into a place off North Timberline Road, Fort Collins in May. Didn't get the sprinkler turned on, tree started looking pretty bad especially foliage on upper branches by late September/early October. The drought during early season may not have been the cause, perhaps the tree was already going to have a problem.
I was told by a tree service company that may have looked at the tree it was lilac ash borer. I looked on the map provided in the bulletins(may have been dated) while searching the data base for an answer, and read a couple other articles neither of these answered my questions:
How to tell the difference between a lilac ash borer and an emerald ash borer? Does it matter in treatment? Is it possible to be rid of the borers? Will I have to treat every other year?
Paid True lawn services to inject fertilizer into the drip line area in the ground around the tree. They have a. 5 & 7 treatment plan. I wasn't there for the first and the second sounds scammy. Some oil treatment sprayed on the tree and leaves (which were the first in the neighborhood to come down) to leave a waxy substance on the branches to suffocate the mites. Now I don't know I have mites and don't know if this is going to suffocate larvae. What stage would larvae be at. How long is the life cycle of the borer's?
The next two treatments are insecticide spraying in the spring and fertilizer. I like anyone else, do not like insecticides. I do not like this tree, perhaps I should get a different tree. I wasn't planning on uprooting a tree. I do love an evergreen tree over deciduous tree. It is a north facing exposure. I believe one insecticide is put directly into the trunk.
Knew a little about pine beetles which seem to be the same type of bug, eats at the Cambian of the tree eventually kills the tree. has to be super cold for a long time to freeze the bugs, they can have more than one hatching as we are a warming climate. easily spreads, especially in wind.
I'm willing to spend some money to have the tree sprayed twice but not without hard evidence this is the way to attempt to save the tree and control infestation in the FTC area. If it's a losing battle, I would replace with a lodgepole pine, Doug Fir or Spruce.
Any information is helpful.
Kind regards,
Larimer County Colorado
Expert Response
The exit holes between emerald ash borer and lilac ash borer are very different. Lilac ash borer are round, about the size of a pencil eraser, and are generally lower on the trunk. Emerald ash borer are smaller, about 1/8" and shaped like a D - they will have a flat side. Only when the insect has progressed far into the tree will you see exit holes at eye level.
Lilac ash borer is a stress related pest and stems from drought, improper planting, storm damage, improper pruning, etc. It generally affects younger trees. If it's still affecting older trees, then addressing the cause of stress is important - like watering on a regular basis. LAB is not a killing pest.
Emerald ash borer is an insect that goes after any tree, healthy or stressed, of any age. It is a killing pest. And treatment to protect your trees will be required for the life of the tree.
Not knowing the size of your ash, the injected treatments (using emamectin benzoate) are going to be the most effective and provide two years of control.
Since you're not especially keen on the tree and it does have some pre-disposed issues (from LAB, drought), you are in the right to remove the tree and plant a tree that you prefer. But you have invested some resources into the tree, so this is a decision that you can make.
If you're on N. Timberline north of Drake, you will want to start treating your tree for emerald ash borer in 2025. Work with a tree care company or arborist who can do these treatments. Here's the list of tree care companies licensed to do work in Fort Collins - and the far right indicates if they do treatments for EAB: https://www.fcgov.com/forestry/arborists
If you ultimately decide to replace the tree, I would steer you towards the various pines or Douglas-fir. Spruce is a tree that prefers more moisture and can get too large for many home landscapes.
tree is prob as old as neighborhood 10+ yrs yes north of Mulberry.
