Vol. 15—1961 - NorthEastern Weed Science Society

429­
where dense B-l'owths, such as greenbrier, present a problem. Hith trained applicators
a fail' degree of selectivity is possible and desirable species can be
"­preserved.
Stem-foliage sprays have been applied indiscriminately as well as selectively.
Indiscriminate applications in September 1954resulted in a 53%
root-kill. Three out of the four tree species present were effectively rootkilled.
However, white oak was very resistant (Table I). Greenbrier was stemkilled
but has presently resurged to its original density. Desirable shrubs
such as mountain laurel, bayberry and high bush blueberry were root-killed.
This points out the undesirability of using indiscriminate sprays. The 1959
commercial treatments are too recent to fully eval.uate , Hcvrevcr, certain
trends are evident. The T-esters appear more effective than Ammateon most
species but especially on root-suckering forms. Sumac and greenbrier are resurging
considerably in the Ammate-treated areas. Of the tree species present"
black birch is most sensitive to the T-esters and red maple to Arnmate. Oaks
and hickories appear most resistant. By doubling the concentration of T-esters,
applications to wet stems and foliage appear effective.
In controlling greenbrier an oil-water formulation with a high concentration
of T-esters (1:20) resulted in over 95%root-kill. Numerous other trials
using water as a carrier gave good stem-kill but resulted in vigorous resurge.
Widespread use of the stem-foliar technique in right-of-way vegetation
management should be carefully scrutinized. Data indicate that percent rootkill
is less than with other techniques. Preservation of desirable shrub- cover
is also more difficult unless the personnel are carefully supervised."" Indiscriminate
applications should be avoided since desirable species are destroyed,
--
as indicated in this study. In addition, unsightly brown-outs result. Only
vrhen other more effective and selective techniques are not feasible, are stemfoliar
sprays recommended. On the demonstration area, the greenbrier cover
directly under the lines represents a cover type where this technique is most
applicable.
The stump treatment has been employed where trees were too tall to
permit them standing under the wires. Therefore, cutting and immediate treatment
of the stumps with 1:20 T or D&Tin fuel oil has been most effective.
?reliminary trials with amino tr~zole in water have resulted in a certain
degree of root-kill during the summer. The addition of a dye to the spray
increases efficiency.
Along the margins of the right-of-way in the forest edge, trees which
have not yet reached the height of the wires are being treated and left,stcmding.
Here notchinG or frilling has been employed. Ammatein notches has been
effective on black birch 2-3" in diameter but ineffective on larger trees.
Best results have been with frills using 1:30 T-esters in oil. Trees up to
4_8 11 in diameter have been root-killed.
Problem of Species Susceptibility
It has already been pointed out that those techniques which tend to get
an adequate concentration of the chemical on the stems and leaves or into the
root-collar area give most effective root-kill. During the investigation,
possible factors accounting for the differential effectiveness and species
resistance to stem-foliar applications have become evident. Since stem-foliar
apFlications are more effective than just foliage coverage it would appear
that absorption probably occurs through both the leaves and bark. As noted