Vol. 15—1961 - NorthEastern Weed Science Society

297.
compatible with grub-proofing insecticides, with 2,4-D, and with ureaform lawn
fertilizers. Its residual activity, based on five replicated tests over a
three-year period, is such that areas tree.ted with dosages up to 18 pounds per
acre at :t.he recommended time in spring can be saf.ely reseeded in fall to
fescues and bluegrasses, alone or in mixturese This fits in with normal
renovation procedures. However, such reseeding is often foun~ unnecessary because
superior turf growth follows the elimination of crabgrass competition.
In extensive evaluations of tolerance of pure stands of turf grass in
1960, it has been found that established stands of Kentucky and Merion bluegrasses
one year old or even younger as well as perennial ryegrass are completely
tolerant of DACTHAL at the recommended and higher dosages. Astoria
bentgrass, one year old, has been found tolerant of DACTHAL at the recommended
rate of 10 pounds. per acr-e-: Chewing's fescue one year old at the time of
treatment with ~L at 10 pOtioo.sper acre was slightly thinned at the
height of its summer dormancy, but had completely recovered by early fall.
The following toxicological data reveal' that this herbicide is not a
hazardous material to use. I'he acute oral LD50 on rats is greater than 3
g./kg. of body weight, and the acute dermalLD50 on· rats is greater than 10
g./kg. of body weight. When included in the diet at a level of I per cent for
30 days, it had no deleterious effects on rats. DACTHAL is non-toxic to blue­
gills or goldfish. It is not irritating to the skin or eyes, and does not
possess a disagreeable odor. However, complete toxicological data are not yet
available and the material should be hnndled with the usual precautions.
This herbicide is a valuable addition to the array of pesticides currently
available for use on turf. Its safety, COMpatibility, and residual, properties
are such that it can easily be fitted into the commonly recommended turf
maintenance programs.