Vol. 15—1961 - NorthEastern Weed Science Society

393.
Pre-emergence Crabgrass Control in Maryland
2
P. W. Santelmann
1
Crabgrass (Digitaria spp) is a universal lawn weed pest throughout
Maryland. Until recently, practical control of these species was limited
to the use of contact herbicides after the weed had emerged (post-emergence).
Unfortunately, Kentucky bluegrass, the dominant lawn species in Maryland,
is susceptible to these materials if they are applied improperly. Recently,
several materials have been developed for use before the crabgrass
has emerged (pre-emergence). However, the- efficiency of pre-emergence
heroicides is materially affected by climatic and soil environmental
conditions. Thus, these materials need to be tested in Maryland before
they can be recommended to the many homeowners of this state.
MATERIALS& METHODS
Plots were established in 4 replications at several locations in
Maryland in 1959 and 1960. Treatments were all applied in established
Kentucky bluegrass lawns, before crabgrass had germinated. In all instances,
there was some rainfall within one week of the treatment date. The
dates and locations were as follows:
A. Treated Nov. 11, 1958, near Beltsville.
B. Treated Mar. 20, 1959, College Park.
C. Treated Dec. 3, 1959, College Park.
D. Treated Mar. 28, 1960, College Park.
E. Treated Mar. 29, 1960, near Clarksville.
All treatments were applied to 2 to 3" bluegrass. At location D
there was a heavy Pon annua stand, at E there was a heavy clover stand.
The materials
used were:
Chlordane, 10% and 20% granular
Dacthal, 50% wettable powder
and 75% emulsifiable concentrate
Zytron, emulsifiable concentrate or granular form
Calcium Arsenate, granular,
Pax, primarily lead arsenate
73% active ingredient
and chlordane
No-Crab, a calcium arsenate and 2,4-D mixture·
Herbicides applied as a spray were in ~ to ~ gallons of water per
100 square feet. Granular materials were applied with a calibrated spreader.
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1/ Scientific Article No. A888, Contribution No. 3204, of the Maryland
Agricultural Experiment Station, Department of Ag-ronomy.
1.1
Assistant Professor, Department of Agronomy» Ma-ryland Ag,x-i cul bn:nl
Experiment Station, College Park, Maryland
'\.