Vol. 15—1961 - NorthEastern Weed Science Society

growing in wa.ter twelve feet deep. We measured Bomeplants of this height
by laying them on a dock.
525.
During the period from 1945-1950 we tried many devices, same chemical,
some physical. Our efforts were unsuccessful and the infection spread. The
first report published in 1946 by the Committee on Water Pollution entitled
"Aquatic Nui.sa.tlceControl in Wisconsin" outlined their progress with sodium
arsenite. We tried So test -area 50 x 100 feet in June, 1949 where the growth
was heavy. In about ten days the weeds in -the treated area disappeared.
Our Weed Committee at that time decided to proceed with caution before embarking
on a program invol vingthe use of sodium 'arseni te .and no t'uaPther application
was made in 1949. On April 22, 1950,' application was made by a
power driven tree spraying equipment at 3.7 PPM in a heaVily infected cove.
No. plants had yet a.ppeared.The purpose of this test wa.s to determine the
resultant concentration of arsenic -at ~ar10us distances and elapsed time fram
point of application. Fifteen samples were taken in one gallon pyrex bottles
and the results _were as follows: "
Location 1 Location 2 Location 3
Sample· Center of·Aree: 50 Ft. Spillway
Date of Sample No. Treated Outside 1/2 Mile
--
April 22, 1950 'I L12 ppm 0·50 0.02
. ~ .. '
Weather Clear
April 23, 1950 2 0.05* 0.34 0.02
Weather Clear '
April 24, 1950 3 2·90 . 0.21' 0.01
\-leather Clear
April
Rain
25, 1950
April 26, 1950 4 0.18 0.03
April 27,28,29, 1950
Weather Clear
April 30-May 1, 1950
Heavy Rain
May 2, 1950 5 0.05 0.04
*This sS,JXI.plewas re-checked. It is obviously too low.
. '
Sample I-Location 1 wa.s taken. 2i feet below surface. The sample was
taken directly after treatment at 3.7 PPM. Arsenic had not yet diffused down
toward bottom. All. later samples were taken at the surface.
Sample 2-Location 1 may have been taken over a fresh ~ater spring.
The results showing thespiilwaywater to be 0.03 -PPlot "Her'" ,r:eaesuring
as it was lower than that permissible in drinking water. In view of th~r.n.