k conover wrote:

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.

--
David E. Ross
Climate: California Mediterranean
Sunset Zone: 19 -- interior Santa Monica Mountains with some ocean
influence (USDA 10a)
Gardening pages at http://www.rossde.com/garden/