I may be mistaken, but these borers will make a hemispherical hole in the
trunk or
branches. Look for them. If you find them, I believe Lindane one of the
treatments
for borers..

Sherwin Dubren

Some Guy wrote:

I have a white birch (I assume it's a paper birch) that's basically 2
big trunks that are joined at ground level and diverge and each trunk
rises to a hight of about 30 ft. Diameter of each at ground level is
probably a foot or slighty more. Tree (both of them) seem healthy,
leaves are fine. For the past 3 or 4 springs I've applied Cygon
around a section of both trunks.

Last year I noticed just under the crotch of one of the major branches
some weakness in the bark. What I found when I peeled off the bark
was several fluid-filled cavities (each about the size of a silver
doller). I basically peeled away the bark over these cavities and
exposed them. The cavities seemed to reach all the way to the
dead-wood of the trunk (about 1/2 inch deep). If I recall correctly,
a bunch of ear wigs probably fell out of these cavities.

This spring I examined the same trunk but lower down and there was a
similar weakness or spongy-ness to a section of bark closer to the
ground. Today I finally went about opening up this abscess. What I
have is basically a gash in the side of the trunk that has been
completely masked by the thin outer layers of paper bark. This gash
starts about 5 ft from the ground and goes up about 4 feet long. On
average it's about 2 or 3 inches wide, but could be 4 inches wide in
places. The gash goes all the way to the wood core of the trunk (ie
the gash is about 1/2 deep). I can see a few worm trails in the
exposed hard wood core so I assume that some sort of borer did this.

Bur what I understand about the bronze birch borer is that they
usually attack higher up the tree. Also, is it common for a verticle
section to be eaten out vs going around the trunk?

Once I cleaned up the gash by cutting out the bits of dry rot I think
that the trunk will heal ok (heck - this gash has been there for must
be years). I figure that exposing this gash to the outside will allow
it to harden up (and it won't be home for ear wigs any more - yuk).

What I'd like to know is

1) Was this the Bronze birch borer?

2) Is there a filler material for trees that's sort of like bondo (for
car body work)? I'd like to fill this gash with something that I can
at least paint white so the tree doesn't look so bad.

PS: I'm located in SW Ontario so my climate is similar to Detroit,
Cleveland, and Buffalo. Also, please post any follow - up (don't
e-mail because I won't get it).

Thanks.