Dutch Elm Disease Resistance CVs

Milmarple milmarple at aol.com
Fri Aug 4 23:45:26 EST 1995


Stephen:  I'm no expert, but do know that DED has rendered American elms
unsuitable for planting at least in the Southeastern United States for the
last several decades.  It can strike at any age and is sited in the
vascular system.  This means that we are completely helpless in fighting
the disease.  There have been "shots" that some folks have sold to
unsuspecting elm owners, but they are ineffective as far as I know and
involve drilling holes in the trunk (ie inflicting further injury).

Once an elm contracts DED, it dies generally in 1-5 years depending on the
tree's health at onset and subsequent environmental conditions.  The
symptom with which I am familiar is sudden browning of the leaves on
branches.  The necrosis will move down the branch from the tip.  You
should consider locating an American plant pathologist in an Eastern state
(perhaps Morton Arboretum, Cornell University or Pennsylvania State
University).  You might also see if you can talk to someone from the
United States Department of Agriculture/Forestry Division.

The good news:  American Elm substitutes that are not susceptible to DED
have come into use in horticulture.  Among the best is Zelkova serrata,
the Japanese Zelkova.  Another is Ulmus parvifolia, Chinese Elm or
Lacebark Elm, which Dr. Michael Dirr (University of Georgia, USA) lists as
showing "considerable resistance" to DED.  He puts U. parvifolia ahead of
Z. serrata in resistance to the disease.   Dr. Ken Tilt  (Auburn
University, Alabama, USA) toured cemetaries a couple of years ago to look
at trees of varying species that survived such a mow-only environment.  He
found several large, magnificent elms and may know something about the
rumblings that the American Elm is making a comeback.  I think his address
is ktilt at aces.auburn.edu.  If that's not right, e-mail me at bbsed at aol.com
and I'll try to get it for you.

Good luck,
Sandra Smith Williams
Director of Education
Birmingham, Alabama, USA



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