Vol. 16—1962 - NorthEastern Weed Science Society

2. Assistant Professor. Department of Agronomy, University of Massachusettt,
Amherst. Massachusetts.
282
CHEMICALQUACICGWSCONTROL 1 ,
Jona.
Ve~gri82
Atrazine (2-chloro-4-ethylamine-6-i80prop,lamino-s-triazine) and
other herbic,ide.areavailable wh~~Il,,,ppear to provida reliable mean8 of
controlling quackgral8 (Agropyron repen8). Atradne:'.uppresses this weed
significantly ~utoften recollllend_" t.j;e. fail.to e.radicate it completely.,
The persi8tence of this weed i8 related to its primary mode of reproduction.
i.e. itl rhizomes which usually ate distributed in the l'low layer. Rhizomes
vary in length and depth and thist·a. our tests indicate (2). i8 at leatt
part of the explanation for failure. in controlling quackgrass with chemicals.
Atrazine sholi14 be applied c.•• clole as pouible to the rhizomes .It
is re.sonable to conclude that mi.i~g the herbicide with the soil should
be advantageous. The ch4llllical will be closer to the rhizomes and under dry
surface .oil conditions mixing ma, provide better moisture conditions for
atrazine to be tAken up by rhizomes and kill them.
The main objective of ou~ trials in 1960/1961 was to investigate
the importance of mixing atrazine ",ith the soil by rototUling versus leavtag
the material on the surface. Comparisons were al.e .. de between fall and
spring applications. In addition'to'atrazine. other promising herbicides
or their combination. were included.
Procedure
Trials were conducted on a well drained gravelly sandy loam. The
area had a good unif.,. stand of quackgrass. Plots wlere 12 ft. by 28 ft.
Three replicates were used. Time :0'£'application and ~ates are given in
Table II. Fall applications were made on October 10. 1960 and spring applications
on April 27, 1961. The quaclgrass was from 5 to 7 inches tall.
On May 19 the exper1lilental area w". "lowed. disked, fertilized and prepared
for field corn planting. On May 22 after seedbed preparation, atrazine and
EPTCwere applied as shown in Table-iII. Treatments 10, 11, 12 and 20 were
rototillad about 4-~ in. deep immedtately following application of the
material. The next day on May 23, Ohio M-1S silage field corn was planted.
Thus treatments appUed on May 22 aMybe considered lUI being made at planting.
Atrazine is only slightly soluble ·in'water (70 ppm i1l':water) and moisture
conditions in the soil at the time of application and for the first ten days
after application are critical fo~tbe effectiveness of treatment. In
Table I. rainfall and temperature data are shown for the various treatment
dates. With each date.of application, the moisture conditions were favorable
for the action of atrazine. On June 5 the whole experimental area was sprayed
with 6 pounds per acre· of dinitro' (DNB') for annull'lW4eedcontrol. There wa•
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1. ContributiCn No. 1336 of the University of Massachusetts, College of
Agriculture, Experiment Station, Amherst, Massachusetts.
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