Vol. 16—1962 - NorthEastern Weed Science Society

Th:Ls ch!~ca1. tx'eatme:n1!_1IhClJ.ose~ as80C!ia.ie~Jw1th lJm'k .beeUcl·'·I. (;
~e;to ~re~ia. ~,pi:Di,~.JF1n.~peJ. ~~JleftJit involve:Cl.,nor- ·'t'
mall;y'18 "pj.1;obed out Qf~l;~~s, but~;,pr dying.,1lrees a:t'I!ll'"
susceptab~.·)i~ 'cbem1~~ted tree~
't~\i~ '.lowl3'·dy1ng.~,(0.
prime targets, end beetle populations ms:ybuild up following treatment
of extensive~. This pOP\llation build-up poses tD questions:
(a) What roles do beetles PlaY in kil11ng treated trees? (b) Will
the build-up cause success~;. ~le attack on neighboring healthy
trees?
" . . .' •. :'e I ",' "~.. ,J
~~ 6f,j;he .chemi.ca1.·a~.sto betrElO.~4 upward in narrow
bends above the point of application, leaving sizable streaks of live
wood ~etween. ~ WQOA.~Ii!: ~~.1nd1cstedl;ly ~ration of liSP
wood following treatment. ·~ry,Uttle ~~xus1ocat:lonis indicated.
This has been verified' by treating one stem of twin red
pines; p,s~ o~ the tre~ :f;tem dies. S1nc:p:~e tree dies;t'roe .f
the to:p do~, a tree ~th a:~ crown is ~i~d... Treeswitb.
large crowns and large areas of live wood between dead tissue may
live ;LolIgel'qr;eveu.recover~ F~ s~ch trees 1;9)~., they must e.itber .j.
be overtopped. and .~d out ~~,colI\Peting .trees .• '__e-girdled through
progressive dying of live tissue along the stem.· Beetle attack may
influence the latter process, but its significance is not known. In
most of the treatments, beetle activity was abundant and trees otten
died quickly. In at least two of the areas, there was little or no
beetles activity; good top-kill was still attained.
Whether or not bark beetle population build-up might become sufficient
to endanger healthy trees is not known. In most of these
treatments beetle activity was sufficient~ heavy to cause the base
of treated trees to be ringed with frass droppings; even so, no untreated
trees were dameged. This fact appears to be especially
significant in respect to the white pine stands which had never
been thinned and contained many non-vigorous trees suppose~ susceptable
to beetle damage.
The use of undiluted 2,4-D amine is cheap. The chemical cost
of most thinnings is about $2.00 per acre. The labor time required
by an experienced Ban using hatchet and plastic squeeze bottle 'With
chemical varies from 1.5 to 4 hours per acre depending mainly on
ability to Il'.ovethrough the plantation. One cut for every two inches
of diameter is otten sufficient. For particularly fast kills to
reduce bark beetle build-up, for trees 'With large crowns, and for
speeding kill following summer treatment, more cuts are needed and
the cost will be somewhat greater.
In sU1lJlllarY, 2,4-D amine in partial cuts is en easy, cheap,
non-hazardous, and effective method of chemi-thinning many conifers
in the dol"ll8nt season. It is particularly applicable to plantations