CONTROLLING WEEDS IN ROADWAYS, ALONG DITCH BANKS
 AND AROUND INDUSTRIAL BUILDINGS

 V. L. Guzman Y/

 The rapid growth of weeds in farm roadways, along ditch banks and on in-
dustrial sites is a serious problem under the subtropical climate of southern FloridA.
Various mechanical means in use for the partial kill of weeds have a temporary effo':
only, and under these conditions it is probable that chemicals may give a better and
more lasting control.

 The herbicides used in experiments reported here are expressed in pounds
per acre of the commercial formulation except for 2,h-D which is expressed on the
basis of acid equivalent. Unless otherwise stated herbicides were applied in 30 gal-
lons of water per acre dilution. The best treatments were repeated in two or three
of the experiments. New chemicals were added and those giving poor control were
omitted from one experiment to the next. The treatments used are indicated in Table
1, whether they were replicated or not in two or more trials, Five tests were con-
ducted, three on mineral and two on muck soils.

 The effectiveness of weed control and the residual effect obtained with
the various herbicides used are given in Table 1. Treatments 1 to 29, inclusive,
were used on roadways of farms located on mineral soils. Treatments 26 to 36, in-
clusive, were used around industrial buildings, or along fences on muck soil loca-
tions. In one case the treated area was near fruit trees and ornamental plants.
Treatments 37 to 62 were used for the eradication of Bermuda grass on a lawn located
on muck soil.

 Best control of grasses was obtained with Dalapon (10 to 20 lbs/A) followed
by TCA (100 Ibs/A). At the rates used, Dalapon did not control broadleaf weeds. Pare
grass was also controlled by two applications, one month apart, of 5 pounds of Dalapor
Retreatment may be necessary after six months to kill new shoots which were not affect
ed by the herbicide. The urea derivatives, Karmex W and FW, when used at low rates
(5 to 10 Ibs/A) and 2,4-D at the 2-pound rate controlled most of the broadleaf weeds
satisfactorily but failed to control grasses. When 5 pounds of Karmex W and 10 pounds
of Dalapon were applied as a mixture good control of grasses and other weeds was ob-
tained. The combination of 2 to 10 pounds of Karmex W with. 2 pounds of 2,h-D sub-
stantially increased their herbicidal properties also. Karmex W and Karmex FW when
used at higher rates (O0 pounds or more) were excellent weed killers, and sterilized
the soil (either muck or inorganic) over a long period of time.

 Two months after the application of herbicides, Bermuda grass began to
grow from the sides of the plots into the treated areas, except in plots which re-
ceived the highest rates of the chemicals. Control of Bermuda was also effective
with the lowest rates of Dalapon. In general two applications of the herbicides
gave better control of Bermuda than double the rate of each when applied only once.
The chemical treatments, even at the lower rates, gave some control of Bermuda when
compared with untreated check plots. The high rates of application of most of the
herbicides (except for Dalapon, which appears to give better control at lower rates,
10 to 25 pounds per acre) gave good control of the grass, but their residual effects
varied. For instance, MH-40 gave good control of Bermuda grass but its effect did
not last more than four months. It appears that on muck soils and for the purpose
of eradication of Bermuda grass, two to three applications of Dalapon at the rate of
10 pounds per acre or Karmex W and Karmex FW at the rate of 0O to 80 pounds per acre

1/ Assistant Horticulturist, Everglades Experiment Station, Belle Glade, Florida