Vol. 16—1962 - NorthEastern Weed Science Society

190
POTATOVINE KILLING IN MAINE~' 1960
H. J. Murp!+y and ,M. J. GOV;E!~
This paper isa progreasrf3port of pote,~o ;vine killing;
studies made in Maine during the 1960 growil:lS l\I~aaon. Eva1uat1-on
of harveated tubers waa made quring the 19Mi;61 atorage aeason.
MATERIALSANDMETHODS:
Five new chemicals whioh had been reported t.o be of some
value for desiocation of crops other than pqi;atoes, and twost~n..
dard potato vine killing materials were teste~ at Arooatook state
Farm, Presque Isle, Maine in 1960-61. ,The primary purpose of
these trials was to determ:~ne the rate and the oompleteness of
kill, and the possible effects on internal tuber quality.
All materials were applied in 100 gallona of water per aore
to green potato vines on the dates indicated in the various
tables.
Using the rating aystem given in Footnote 2 of Table 1, kill
ra tinge were made at seven, and again a 1t fourteen days after
matorials were applied.
Triplicate samples of tubers were taken/lt harvest, from each
of the six replicates for post-harvest studies. One set of samples
was uged for residue analysis. The romaind.ng, samples were stor~d
at 4S F. and ret SOoF. for examination duri!l$,thewinter months.,
Storage oxaminations consisted of snipp1!l8 the stem end from eaoh
tuber and classifying each tuber as to peroent of vascular ring
showing disooloration. From those ratings, weighted values were
computed as reported in tables 1, 2, and 3. ~
RESULTSANDDISCUSSION:
Table 1 and 2 indicate tho effoct of several desiccants on
vines and tubers of the Katahdin and Kennoboc"potato varieties.
Data in these tables indioate that all materials were of some
value in killing potato vines. Methylated napthalene, howeve:t?,
was not partioularly effeotive. Ammoniumthfoo¥anate and Reg16ne·
(diquat). a.t all rates oaused oonsiderab1e intorhal tuber disooloration.
Disooloration was more anvere with the Kennebeothan
with the Ka~e.hdin variety, probably beoause of higher air and
Associate Professor of Agronomy, University of Maine, Orono~
Maine and Teohnical Assistant in Agronomy, -Aroostook Stato
Farm, Preaque Isle, Maine. - .1