Vol. 16—1962 - NorthEastern Weed Science Society

CHBMI-THINNINGWITH,AIrlINES IN THEDORMANT SEASON
429
Robert R. MorrowJ.
"Hardwoods
Cons1derab1eearly work in chemi-thinn1ngbSrdwoods was reported
in 1959 (3). At that time the importance of a eqm,plete frill for
dormant season deadening of most NortheasternU~ted States species
was stressed. Top-kill was cllousedby adding cil~cal to the frill, .
to make a zone of dead wood. Successful chemi-Wdles were made with
2,4,5-T in kerosene, 2,4-Din kerosene, and .rosene alone. The
former chemical caused a wider girdle and appea3d to hasten topkill
by as much as two years1n comparison with 1'2,4-D and oil alone.
Wiant and Walker (4) have recently confirmed t~ Glil alone is sufficient
to cause top-kill when e4ded to frilJ.s.··'
In recent years there has been considerable-;I.nterest in the
performance of amines of 2,4-D and 2,4,5~ in ~arison with esters.
Such interest is spurred by reports that top-k:1.J.a., especially of oaks
in the growing season, has resuJ.ted from aminee4D partial cute (some'
li terature reviewed in reference 3). Comparatiw tests of amines, ,
esters, and oil were made in 1957 aniI. 1958 on a-.riety of species
in woodlots in southern New York. All chemica1lf rwere applied in a
complete frill at a rate of 2;"3 ml. per inch of,·tiameter. Most treatments.
were made in October and November; a few W2'emade in February •.
Table. 1 gives the approximate .t:tmerequired for -~b percent of the
chemi;"girdled trees to be 90 percent top-ld.lled~·
In mo@ttrees ,that required two to four YeEll'Sfor top-kill l there"
was little kill the first year. Occasional treg'cling to life for
many years, even though completely girdled, prerilliably thr01.1gh root
grafts. In general there was little difference l!Ietween trea.tments
in the time required for top-kill. A few cases 'Of live wood bridging
girdles were found in the 100(1 ahg ~,4-D amine1treatment. These
occurred on large vigorous trees, mainly red map;ij!. This may have
resulted from polilr spreading and transJ.ocation cStamine in water at
near freeZing temperatures. On the other hand, kerosene s];:reads and
soaks into woody tissue rapi~ .at low temperatures.
lAssoc. PrOf. of Forestry, Department .of Conservation, Cornell University.
The' author wishes to acknOwledge the ektensive cooperative
tests carried out' in western KeY'.York by the Nelt:l'ork State Conservation
Department under the supervision of District Forester E. J.
WhaJ.en.