Subject: Re: Re:re. Should I cut my elms
From: "Bill Robinson" <roseguy@flash.net>
Organization: All USENET -- http://www.Supernews.com
Date: Wed, 8 Apr 1998 07:53:19 -0700
Message-ID: <MOD$980408.29240@rec.gardens.ecosystems>


I made the statement that "the [Dutch elm disease] pathogen
is a decay organism that feeds on weak, broken, damaged or
dead growth. For the most part, the prime victims of Dutch elm
disease are the old, neglected, and damaged trees".

I had some bum information. I was wrong.

Steven Cangemi points out, and correctly so, that there are
communities that have lost all or most of their elms and that
the elm bark beetle that carries the pathogen also feeds on
healthy elms.

What I should have said was that the elm bark beetles are
attracted to the old, neglected, and damaged trees which they
use as breeding sites and they are attracted to younger and
healthy trees as sites for feeding. The feeding sites on the young
& healthy trees can become infected. Young and healthy elms do
have better resistance to the pathogen but it is sometimes
inadequate. Trees stressed by drought, etc. don't have much of a future.

The organism that causes Dutch elm disease is caused by the
fungus, Ceratocystis ulmi which becomes a threat to the tree once
it gets into the water conducting tissue of the tree. The pathogen
produces a gum that restricts the passage of water and nutrients.

See the Michigan State University Extension publication on Dutch
elm disease @ >http://www.msue.msu.edu/jackson/hort/dutchelm.htm

Bill