Vol. 15—1961 - NorthEastern Weed Science Society

PRE-ID-lEf\GENCECONTI\OLOF CR.ABGMSSIN LAWNWRYl
E. J. Rice and C. R. Skogl ey2
There is a perennial· search for chemicals ,,,,hich will centro], crabgrass in
established> tilrfgrass areas .. '. Tlris etllesthaa an ililierent problem of selectivity;
to kill the crabgrasssee'd. 0rplant: without damage to the basic grasses. Our
1960· pre-emergent test.is another step toward this goaL
.. Y.aterials and Methods
This study was carried out on an old stand of lawn-type turf consisting
primarily of cclonial bentgrass with a uniform yet lesser amount of Kentucky
bluegrass and. creeping red fescue. A heavy stand of crabgrass was present
during the previous season and the test area was also overseeded with crabgrass
seed in early April of 1960.
The soil was classified as a Jridgehampton silt loam, a deep, well-drained
soiL Ii'ertility was low and the pH reading 'vas 5.7. To favor crabgrass growth,
the cutting height was maintained at 1 inch and fertilizer was applied once,
after crabgrass germination. There was a 5 to 10 day interval between mowings,
governed by the growth.
The 1960 growing season was drier and cooler than average. There was no
water supply so the turf received only natural precipitation.
The trial was established using a randomized block design with each treatment
in triplicate. Thirty-seven treatments were included on plots measuring
4 x 10 feet each.
The materials were applied between April 16 and April 26. Grass growth
was slow because of the cool spring. ~lettable powders and emulsifiable concentrates
'vere applied in \vater at 250 gallons per acre, with a low pressure
s~rayer employing a flat-fan t~e nozzle. The dry formulations were applied
by hand in a mixture with sand except the Iialts formulations which were applied
with a Scott's spreader at a setting of ten.
Periodic observations were made following the treatments to observe turf
injury or discoloration. Final control readings '~ere taken on September 23,
19.60, .hY.