Ash trees may continue to have major problems this year
March 15, 2010
I’m not exactly telling you to kiss your ash goodbye, but we had more than normal problems with mature ash trees in 2009 and the future does not look bright.
We have mostly green ash trees in central Kansas although there may be a few white ash. White ash is very similar but more adapted to eastern Kansas and beyond where the rainfall is a little more plentiful. Green ash gets a bit taller. The wood of both is famous for furniture and baseball bats, although these days only in the majors where aluminum bats are still outlawed. Since we don’t have much woodland they are strictly ornamental and shade trees here.
Last year, every third tree call I had was on ash. I ventured out and looked at a number of these thinking it was probably the classic ash-lilac borer, it wasn’t. Ash lilac borer and occasionally the banded and red-headed ash borer can be problems, especially on young ash trees.
Lilac-ash borer, which flies from April through June, is the number one problem-borer of ash. Small trees seem to be most susceptible, along with under-watered and trunk-damaged trees. It’s also likely that trees in poor condition have less capacity to recover from borer attack.
What I saw was damage up in the canopy of trees, not on the base of the trunk. I looked for borer holes but in many cases found very few. Most of these had no lower branches so it was really hard to get a sample.
The symptoms looked a lot like the dreaded Emerald Ash Borer which has not been found in Kansas as of yet. We are trying to keep it out. It has been destroying ash trees in Ohio, Michigan and other states northeast of here. There is no known treatment.
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I talked with Jim Strine, area forester from Hays and Tim McDonnell, community forestry coordinator out of Wichita and they came up with the possibility that it was either the eastern or western ash beetle. This too, tends to work on the top of the tree.
There are other problems on ash trees such as ash yellows disease. So much so that K-State is recommending that you do not plant ash trees. There are other trees with fewer problems.
In the meantime, what should you do if you have a special ash or two that you want to save? Kicking it won’t help!
The old standard term treatment for most borers was lindane and then when they took it off the market it was Dursban. These need to be used in May or early June.
The best way to control borers is to apply insecticide to the bark. Applications are most effective when adult borers are flying. These need to be used in May or early June. Permethrin 38 percent (Astro) and spinosad are the most widely labeled insecticides for borer management. Sevin has some labeled uses for borers. Control of infested trees is difficult to achieve because you can’t get the insecticide into the area where the larva are feeding.
Then there are the soil applied drenches although they are labeled for general borers and not specifically for ash-lilac borer. They may be of some help as a preventative applied in the spring. These may include Bayer Advanced Tree and Shrub Insect Control or Ortho Tree and Shrub drench. These contain imidacloprid. It should be applied by label and then watered in. I have been recommending that people, who had sick looking trees last year, do this early treatment now, as well as the bark treatment later.
I normally do not recommend fertilizing established trees if you are fertilizing your lawn. The exception may be where you have iron chlorosis or sandy soil that may be low in organic matter and nutrients. For the most part, our soils have adequate nutrients for established trees. Your lawn fertilizer is supplying all that the tree needs. However, if you have a tree that is under stress and may not be vigorous, a mild dose of fertilizer in liquid form may be beneficial.
Another way to help prevent damage is to maintain a tree’s vigor through consistent, year-round watering and to avoid bark injury.
Eventually, if the Emerald Ash Borer makes it here, we may just have to cut and burn the ash trees like we will the Austrian and Scotch pine. Thus my recommendations are probably only a temporary fix.