Vol. 16—1962 - NorthEastern Weed Science Society

Empb4sis was on testing DOD-volatile esters of 2,4-D lmpregaated in
granules. Series of randOlllized. replicated trea~ts, with checks, were
made on liS-acre and l-acre plota in fresh and brllidciah water habitats
during ti~, of slack low water. 'lbe dosage rate .... re 10, 20, and 30
pounds a. e.. per a... Chemiuls WIre applied duriiIB the latter part of
May and early Juae after watend.l~ll was high enouahto reach the water
surface at ebb tide; most of the treatments were. made when the temperatul:'e
of the water was above lSoc. Other phenoxy formulations were applied at.
dosages of 5, 10, and 20 pounds' •••• per acre on Lilo-acre plots in both
fresh and tidal water ereas; X'epU.catioDS were made at the 10 pound a. e.:
per acre rate. testing was cont1aued until after taitial flowering.
Additional tests of both e,tews and amine sal~ of 2,4-D were made et
high tide, when dispersal of herbicides by currents would be greatest;
these tests were made on 1/2-acre ADd l-acre plot.. EDdothal. which is a
highly .oluble and readily dispUs.d formulation, was te.ted at 40 pouDd,I
a.e. per acre on a 2 1/2-acre plot in a small bay at dead-low tide to see
whether it would be effective under such favorable conditions.
Herbicides Were applied frOlll a l4-foot boat. "tlich was propelled by, a
5 horsepower air~thrust motor. Granular herbicides were applied with a
knapsack power sprayer (Solo Model 60) strapped to a seat in the center of
the boat. A hopper .of the type ,used for farm tractors was cradled in a
wooden fr8llle on the gunnels of the boat and attached to the knapsack POlfllr
uDit with a rubber bose. '1be gr ... les were fed by::sravity into the rotor
of the air-thrust unit and dispersed through a 4-iach rubber hose and head
device in a 10';'foot swath. 'lbe flow of granules was regulated with a
pointed stick that fitted the opening of the fuDDel. Liquid formulations
were applied with coaventional power spray equipmeat from a boat propelled
by an air- tbrus t motor.
Results
Distributiog Studies. The rasults of the survey in the Chesapeake Bay
and PotOlllac River region in 1961 indicated that the area of infes tetioo of
Eurasian watermilfoil toteled about 100.000 acres &Del that new esteblishments
were occurring at a rapid rate. This is in contrast to its known
range of 50,000 acres in 1960 (Stotts, 1961).
'1be rapidity of invasion 111illustrated by the records of aDDual OCtober
surveys. of the Susquebal:lna Plats, an area of major importance for waterfowl.
Previous sampling of stetions sbowd the following. frequencies of occurrence
at vegeteted stations in successive years: none, 1957; 1 perct,t. 1958;,
47 percent., 1959; and 84 percent, 1960 (SpX'inger et al., 1961)A '1be stJtYey
in 1961 X'evealed that Eurasian Rtermilfoil was pX'Uent at 88 pucent of' the
stations. 1Jl July 1961, a silil!lar auX'Vey showed that 71 percent of the :
stations had Eurasian wateim1lfoil.
445
1/ a.e ..- = acid equ.ivai~t.
~l Also, P. 'to SpriaSeX'. V. D. Stotts. and C. K. Rawls, se., unpublished
field DOtes. 1961.