On Mon, 9 Aug 2004 11:27:44 +0100, Janet Tweedy wrote:

a red oak (Quercus rubra) [is] absolutely covered
in wasps. They are attracted by the honey dew left by presumably the
aphids which are higher up the tree.

Any evidence of ants farming the aphids? Take a hard look at the
trunk and if you see ants scurrying up and down, consider that
sufficient evidence.

If ants are involved, then if you can keep them out of the crown
of the tree the aphid problem should decline and fall. Some kind
of barrier around the trunk would be called for. The sticky bands
used for wintermoth control will work, but if you can get Sevin
(carbaryl) and spray a band, say, 18" wide around the trunk and
renew it every two or three weeks, that will suffice.

Ants are loath to cross a band of sevin -- they taste it with
their feet -- and if they do, they die.


If ants aren't involved, then painting the trunk with Cygon
(again, if you can still get it) might control the aphids.


Unfortunately, effective special-purpose insecticides such as
Sevin and Cygon are nearly impossible to obtain any more. The
greens have completely driven them off the market, and the
pyrethrins that are left simply won't work in the same way.


--
Rodger Whitlock
Victoria, British Columbia, Canada
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