Hi, I have an 80+ year old oak tree in my yard. Last year had Arborguard come out and they told me it had a beetle infestation and that the cost to treat it would be in the thousands. Needless to say, did not treat. Haven't noticed anything all winter, but now I notice ants crawling around the base of the tree and into the bark (maybe the beetles are coming!) Does anyone know of a good way (preferable non-toxic to my cats) way to help my tree out, maybe support it with more nutrition and also keeps the bugs out? Do you think it will kill the tree? Thanks-- Kirsten
My valley white oak (Quercus lobata) always has ants, but it is quite healthy.
If you do have a problem with borers, there is a systemic insecticide for trees that comes in little plastic "bullets". You have to buy enough to space them about four inches apart around the trunk about 3-6 feet above the ground. You use a drill to make holes (the package describes the size) in a spiral that winds twice around the turnk and insert the "bullets". I used this on an ash tree that was severely infested with ash white fly, which almost defoliated the tree and made a sticky mess in my yard and even inside the house. I had to do this two years in a row, until a newly introduced parasitic wasp brought the white fly under control.
I don't remember the name of the product, but I found it at a local nursery. Follow the instructions carefully. It should be safe for your cats, which should avoid eating oak leafs (which can be toxic).
I would avoid over feeding an oak. Many oaks prefer a "lean" soil. One light application of regular lawn food (without insecticide or herbicide in it) might be okay. Scatter this across the entire area under the tree's branches. Oak roots often spread as wide as the canopy.
Be careful with water. If your oak is a variety that likes moisture in the summer, be mindful of drought conditions and keep it watered. If your oak is like mine -- native to a climate that usually has no rain in the summer at all -- do not irrigate.
The best thing you can do to promote general tree health is to mulch. Use wood chips, pine bark, or any organic material that suits you aesthetically. Apply it in a layer 3 inches deep all around the trunk. Do not heap mulch against the base of the tree; you should be able to see the root flares where they enter the soil. Cover as wide an area as you are willing. I'd say minimum 6 feet from trunk, but for a tree as large as yours you might even go farther.
Mulch reduces competition from grass and weeds, thus eliminating injury from string trimmers. It blankets the soil so temperature spikes are less severe. It retains moisture. As it decays, it releases nutrients into the soil and loosens compaction, thereby reviving the soil ecosystem and making roots happy. Happy roots make happy trees. Happy trees are better able to resist attack from disease or pests.
Good luck,
keith For more info about the International Society of Arboriculture, please visit
I don't believe their diagnosis since the price of the treatment tells me they are less than ethical. Have the tree re-diagnosed by a CONSULTING arborist, i.e. one with no program to sell you. Go to the ASCA website to find one in your area. -
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