Vol. 15—1961 - NorthEastern Weed Science Society

.32.
for plant height, weight, and rhizome weights. Six replicates were used
­
for each tr eatm ent,
Test solutions were prepared by dispersing the wetting agent in
water, and diluting to the required concentration" then adding unlabelled
sodium dalapon to a concentration equivalent to 10 pounds to 60 gallons.
A sample of 2_C 14 labelled sodium salt of dalapon having a specific
activity of O.98 millicuries per millimole was used for the test. The
oolution employed contained 1.35 mtcrocurtes per milliliter.
An area 5 mm, by 50 rnrn, on the upper surface of the third leaf of
each test plant was walled with lanolin. This area was then supported in a
horizontal position, and flooded with one-half millilU'er of the proper
dalapon-wetting agent solution. A two hundred lambda aliquot of the 2-C 14
labelled sodium dalapon solution was added to the wetting agent solution on
leach leaf, after which the leaves were allowed to dry.
It was thought that perhaps the herbicide might be retained by the
lanolin ring" or that the wetting agents might affect such a retention. This
was checked in the following manner. Lanolin rings were formed on thin
glass cover slips, and the rings were then filled withdalapon-2-C 14 solutions
in water and with various wetting agents. After standing for one hour,
the cover slips were washed under running water for ,30 seconds. The
cover slips were then broken with tweezers and dropped into vials of scin­ ­
tillation solvent. After shaking to dissolve the lanolin, the vials were
counted and background counts were ~btained..Jt..w.as considered that the
lanolin ring per se had no interaction with either the herbicide or the wetting
agents used.
After five days, the plants were dissected and the individual leaves,
stem, rhizomes, and roots were cut with shears into one-half inch s egrn entc,
The various parts, 'except 'for the treated leaves, ,,;iere ground in a glass
homogeniz er-, The pieces of treated leaf (with the lanolin wall) were placed
into vials containing 5ml~ ,of water'containing sodium carbonate slightly in
excess of saturation. The VialS wer-e 'heated to a ppro xlm at ely 99°C. ,
placed in a freezer at 18°C. for 24 hours, and then crushed with a stirring
rod. After grinding or crushing#. each sample was centrifuged and the
supernatant liquid removed: for analysis.
Counting was done in a Packard tri-carb automattc scintillation
counter using a solvent system consisting of 70% redistilled toluene and 30%
absolute ethanol, and which contained 4.0 grams of 2..5-diphenyloxazole
and O. 1 gram of 1, 4-bis-2-(5-phen,yloxazolyt)-benzene per liter. One-half
ml, of supernatant liquid from a sample preparat~ was added to 191/2 nil.
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