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From: "David E. Ross" <nobody@nowhere.invalid>
Newsgroups: rec.gardens
Subject: Re: What makes holes in walnut trees?
Date: Fri, 11 Jul 2025 22:09:31 -0700
Organization: I am @ David at rossde dot com.
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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/
>>
>>         [snipped]
>>
>>> Anyway. No chemical product exists which could act against an
>>> ongoing infestation. Usually you have to get rid of the beetle.
>>
>>         [more snipped]
>>
>> 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>