Vol. 15—1961 - NorthEastern Weed Science Society

544.
Summary
1. Six experimental plots (SO X So ft.) were selected along the
west shore line of Long Pond.
2. The observations on these plots were made from May 25­
September 20, 1960.
3. Preliminary study of the following conditions and organisms
was carried out on June 8: bottom temperature, pH, diSsolved
oxygen content, plankton and benthic forms, large
aquatic vertebrates, and pondweeds. The same routine of
study was repeated on July 1, July" July 20, and
September 1,.
4. The six experimental plots were treated With different oonoentra.tions
of 2, 4-D Aqua Granular (Crop Rider). These
concentrations ranged from 0.9 ppm, 1.3 ppm, 1.8 ppm,
2.6 ppm, to 3.6 ppm.
5. The periphery of eaoh experimental plot was preoisely defined
by the surrounding untreated green area. This implies
that diffusion of the granules from the plot is negligible.
6. MYmEhaeaodorata and Brasenia sp. were suooessfully
elIminated by all oonoentrations.
7. Utrioularia purpurea was definitely reduoed but not
eliminated by oonoentrations of 1.8 ppm, 2.6 ppm, and
3.6 ppm.
8. The temperature of the bottom water varied between 68 0-78 0
F.
9. The pH fluotuated from 7.6-7.0, and varied as did the oontrol.
10. The dissolved oxygen oontent fluotuated from 8 ppm in both
June and September to a low of 4 ppm in mid-summer. Treated
plots varied With the control.
11. Plankton was oonstantly represented in both oontrol and experimental
plots by the same forms as in preVious years.
During the eight days after treatment,' both the aotivity and
numbers of the population appeared reduoed. By the end of
three weeks, the POPUlation had regained its original oondition
before treatment, and similar to the oontrol.
12. Benthio forms were oonstantly represented by forms identioal
with those of preceding summers. Their numbers were not
effeoted by treatment. They varied as did the oontrol.
13. Fish of all ages, frogs, and turtles were present and vigorous
in both treated and control areas.