Vol. 15—1961 - NorthEastern Weed Science Society

264.
E;xPer1ments in Pre-emergence Crabvass
Control
. by R. G. Mower and. J. F. Cornman*
During the 1959 growing season a number of chemicals gave very promising
results for pre-emergence crabgrass control both in our own experimental work
(1) and in experimental work at other stations. This paper reports the continuation
of trials 'With the more promising of these pre-emergence chemicals.
Both fall and spring treatments 'Were made with a variety of chemicals. A
third se't' of plots inqluded only l'Jacthal and a commercial formulation of it
a.t increaSing rates to observe possible turf -injury effects.
The experimental area was located at the Comell Turf Research Plots,
Nassau county Park, East Hempstead, Long Island. The treated turf was mu.chlike
that used in preVious trials (1), conSisting of a good stand otcmixed
Kentucky bluegrass and red fescue with a scattering of volunteer bentgrass
and clover.. The turf was ~ta1Ded at abo.ut.lt inchpeight, well fertilized,
and adequately irrigated; During the 1959 season this area, like -the untreated
areas of the 1959 plots, was rather uniformly and heavily (~) infested
with crabgrass.
The pre-emergence chemicals were applied at two seasons. Fall treatments
were made·on NOVember-13, 1959 and th~ spring treatments on "March 31, 1960.
The experimental design for both the fall and spring treatments was a canplete
randomized block with treatments in triplicate on 7 x 7' plots. Serving as
checks in the fall treatments were seven plots, and in the spring trE!atments
eight plots. Dry formulations were broadcast by hand without dill,\ent. The
liquid formula'ti:$.ons $lld wetta'9le powders were applied with a sprinkling can
in water-at the: rate of aboUt 10 gallon! per 1,000 sq. it ..
Results and discussion
Cra.bgrasa control
The srowing'seasoQ. of 1960 on "Long Island was not a" good crabgrass
year,," especiall.y- in the d.en$e stanp- of v;Lgorous turf·- on our plots. As a
result it was· impossible to ~e crabgrass cont.rol estimates in terms of
prOPortiQll of the area covered. To have any record at allot thei1"esults
it was necessary to count individual plants. These counts are shown iJ:;l.
Tables 1 and 2. While the average counts for the check plots seem large atfirst
glance, it should be noted tha.t almost all of the plants in all of the
plots were -very small and much crowded by the vigorous canpeting turf. Henc.e
even in the most badly infested checks the tot&l area occup1ed by crabgrass
was scarcely more than 1 or 2 pet.- oent ot the plot area. The differences in
counts between treatments and between treatments end checkS aga1ll is superficially
large, bu.t the vari.atioGe 8D1O.Qg:thereplicates was-great enough so
that, uponstatisticalanalysis,1t appirs that the$e superficial. differences
~ ;'r " '
* Turf Research ASsistant and professor of Ornamental Horticulture, respectively,
Cornell University, Ithaca, N. Y.