Vol. 15—1961 - NorthEastern Weed Science Society

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Surfactant
Produced bz: .
31 •
Duponal .... f A Flake Anionic E. L du Pont de Nemours
and Company
Ethomeen 8-15 Cationic Armour Chemical Corporation
Tergitol T MN Non-ionic Union Carbide Corporation
Polyglyco126-2 Non-ionic The Dow Chemical Company
Tests to determine retention on the leave~ of quackgrass and tests
to determine the required dosage of dalapon-2-C 4 showed that the nonionic
surfactants were superior to both the ionic ones. Ac~ordingly,
Tergitol TMN and Polyglycol 26-2 were used in the rest of the experiments.
One of the early tests which gives some information concerning the
effect of surfactants on the penetration of leaf surfaces was run as follows:
A. group of quackgrass plants in the five-leaf stage was selected for
uniformity. Glass vials 5 mm, in diameter and 70 mm, in length were
filled with various labelled dalapon and wetting agent solutions. and the
third leaf of each quackgrass plant was inserted into a vial to a depth of
50 mm, Evaporation and plant uptake were measured after. 24 and 48 hours.
After 48 hours, the . plants were harvested and the various parts were ex­.
ammed for radioactivity using liquid scintillation counting. Jror-the remainder
of the tests" formulations containing unlabelled dalapon sodium
salt at a concentration of 10 pounds in 60 gallons were used. A range of
wetting agent concentratiOns of 0, 0.05%" 0.10/0" and 0.2% wetting agent in
the final herbicide solution was uaed, These percentages are in the higher
range of the concentrations of wetting agent used in field applications of
dalapon at recommended rates.
This experiment was conducted with pot-grown plants of quackgrass
(Agropyron repens (L. ) Beauv.}, All test plants were grown from two node
sections of quackgrass rhizomes which had been selected for uniform size
and weight from a clone. The test plants were produced and held after
tr-eatm ent in a Percival controlled envtronmem chamber with a ..day temperature
of 78°F. and a night temperature O,f56,oF. ~ having three fC)ur-degree
temperature steps between the extremes, The plants were grown under a
twelve-hour day length with a maximum intensity of 3,900 foot-candles at
bench height. Light intensity was also regulated thr-ough three Incr em ents
per cycle, with nine hours ofmaxfm um intensity light during each 24-hour
period.
Plants W'ere selected for uniformity of sprouts shortly after emer-­
-gence~ and again at the three-leaf stage. A firv:\l selection made when the
test was started resulted in an extremely uniform group of plants in the
six-leaf stage of growth, each with a three-leaf shoot at the second node.
Preliminary trials gave coefficients of variation of from eight to ten percent