Re: What makes holes in walnut trees?

On 7/11/2025 3:02 PM, bp@www.zefox.net wrote:

David E. Ross <nobody@nowhere.invalid> wrote:

On 7/10/2025 10:48 PM, Michael Uplawski wrote:

bp@www.zefox.net wrote in rec.gardens:

>
http://www.zefox.net/~bp/walnut/

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        [snipped]
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Anyway. No chemical product exists which could act against an
ongoing infestation. Usually you have to get rid of the beetle.

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        [more snipped]
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There are actually two chemical methods of eliminating borers in trees.
>
One involves a drench of Imidacloprid.  The amount depends on the
diameter of the trunk at the height of your chest.  The drench is
applied in the root zone.  DO NOT use Imidacloprid while the tree or any
adjacent plant is blooming because it is very harmful to bees.  On the
other hand, it is harmless to birds and mammals; thus, nuts from the
tree would still be edible.
>

 
Last I heard imidocloprid has been banned in California as of this
year (or thereabouts), at least for retail sale.

[snipped]

I read the regulation.  It seems to make an exception for use of
imidocloprid on food plants.  I have only used it on my dwarf citrus
when I see damage from leaf miners and on my peach tree to prevent
flat-headed bark borers.

The latest information on the Web from Agriculture and Natural
Resources, University of California, about citrus leaf miners still
suggests using imidocloprid.  However, that Web page has not been
updated since 2021.  You might want to contact your county's Agriculture
Extension for clarification.

--
David E. Ross
Climate:  California Mediterranean, see
<http://www.rossde.com/garden/climate.html>