Vol. 15—1961 - NorthEastern Weed Science Society

34.
These results show that evaporation over a 72-hour period is approximately
0.1 m l, and of little s~ificance in comparison with the other
measurerri ents, The results of added wetting agent are striking, and show
that the addition of non-ionic surfaetants increases penetration of the leaf
.eurface when the leaf is immersed in the solution. Radioactivity counts were
proportional to these uptake data and confirm ed that the observations represent
uptake rather than evaporation. .
For the leaf surface tests, the applications of the dalapon and surfactant
formulations were made to the third leaf of quackgr-aas plants in the sixleaf
stage. After fivedays,the various plant parts were examined by liquid
scintillation counting. The results obtained with dalapon alone are shown in
Tabies 2 and 3. .
Table 2.
The Net Counts Per Minute
Bbtained From Leaves of Quackgrass Plants
Treated 1;/ith C 4 Labelled Dalapon in Water -\i~ ith No Added Yt etting Agent
(Background Count = 28. 3 cpm, )
----------------------------------
First Second Third* Fourth Fifth Sixth
~e'pl!.c~e__ L~a! L~af L~a! .!=e~f !:-e~f ~eaJ _
1 26 37 8684 163 327 346
2 20 38 7872 216 355 337
3 as 37 7432 206 329 295
4 24 31 8425 189 273 332
5 27 40 6915 174 285 380
6 20 28 8439 225 286 256
--~---------~------_._-------------
Average 23.7 35.2 7978 195 309 324
Standard
Deviation 3.1 4.2 679 24 32 43
c. V •. (%) 13. 1 11.9 8. 5 12.3 10.4 13.3
*Application made to third leaf.