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Scott, Walter E. (ed.) / Wisconsin Academy review
Vol. 3, No. 4 (Fall 1956)

Chambers, E. L.
The Dutch elm disease in Wisconsin,   pp. 148-149

Page 149

Fall. 1956                                        149
larger number of samples were screened out as showing no
evidence of the- brown discoloration characteristic of the
disease making culturing unnecessary.
                  The principal vector of the Dutch elm di-
               sease is the smaller European elm bark
               beetle (Scolytus multistriatus). This is
               one of our introduced pests and was first re-
               ported in the East in 1904, and it was not
               until 1952 that it was found in Wisconsin.
First reported from Milwaukee County, annual surveys made
by the State Entomologist's Office reveal it to be present
in 19 southeastern counties as of September 1956, the farth-
est north being reported at Fond du Lao and Green Lake
Counties. This beetle appears to confine its attack to
elm, showing preference for breeding in recently cut, brok-
en, or dying elm but feeds upon the healthy trees and be-
cause of this habit spreads the Dutch elm disease when the
adults emerge from infected elm wood where they become con-
taminated with and carry the spores of the disease.
     On the healthy trees, the work of the beetle can be
detected by the feeding scarsin the crotches of the small-
er twigs. Evidence of attack on dead or dying elm trees or
parts thereof is the small round emergence holes made by
the adults, often the bark of such trees appearing as though
hit by "bird shot." Examination of the wood beneath the
bark of such an infested tree will reveal a characteristic
pattern of tunnels. The female makes a vertical tunnel
following the grain of the wood about two inches long in
which she lays her eggs, and the larvae upon hatching cut
similar tunnels at right angles to the original one. There
are two generations each year. The native elm bark beetle
gHylurgopinus ruipes ) is also of importance as a carrier
of this disease, and in some areas of other states it is
             still the only carrier present.
                 The Wisconsin Department of Agriculture
           *has been able to obtain excellent cooperation
        :s S from all of the municipalities where this di-
             sease has been found.  Diseased trees are be-
             ing removed, burned promptly, and the area
             within 1,000 feet sprayed with DDT and sanita-
             tion practices carried out. All efforts of
    '- Hi   m control must be directed toward the beetles and
             elimination of their breeding places.  Elm
             material can be destroyed by burning or by turn-
             ing and wetting all bark surfaces with a 1%
          emulsion of DDT.
                 Where elm is the most logical tree to use,
             it may still be planted if some provision is
             made for its protection against the Dutch elm
             disease.                      # # #
Fall. 19 56

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