4H9HHHhHHKMH MHHH;H5;-HH (;-!HHHHHHHH;-;KHS
This report contains suggestions de-
rived from experiments conducted on
chemical weed control on sugar cane
growing in organic soils during the
period 1952 to 1956,
EVERGLADES STATION D. lEO REPORT 56-16
Belle Glade, Florida
June 5, 1956
SUGGESTED METHODS FOR CONTROLLING VJEEDS IN SUGAR CANE ON
V. L. Guzman
SUGGESTIONS FOR THE CONTROL OF ITEEDS AND GRASSES IN SUGAR CANE
ON ORGANIC SOILS /
V. L. Guzman
1- 2,4-iD mine salt (containing 4 pounds of active material per gallon)
2- Karmex W,801 active (called in the past CMU)
3- Karmex DW, 80% active'
4- Dowpon, 85 active (called in the past Dalapon)
5- TCA, .90 active
Residue tolerances of these herbicides have been established, since recom-
mendations for their use in sugar cane are indicated on the manufacturers label.
A- What to apply- Herbicides, rates and type of control-
Herbicides Control Rates: Pounds per covered acre
2,4-D amine salt* Weeds 2.0 1.5
Karmex W or DW 2.0 2.0
2,4-D + Karmex W 2.0 + 2.0 1.5 + 2.0
Karmex W or 1DW Pellitory weed 2.0 2.0
Dowpon Grasses 10.0 2.5 to 5
Dowpon + 2,4-D Weeds and grasses 10.0 + 2.0 2.5-5.O + 1.5
TCA Grasses 20.0 15-20
TCA + 2,4-D Weeds and grasses 20.0 + 2,0 15-20 + 1.5
2,4-D is expressed in pounds of active ingredient. Other herbicides are ex-
pressed in pounds of the commercial grade.
Three applications of 2,4-D, or Karmex W or a mixture of the two can be used
per season without detrimental effect on yields. Excellent control of weeds was ob-
tained with the latter mixture. In most cases grass control with Dowpon when used
up to 10 pounds per season gave economical advantage over the cultivated and hoed
check. Five pounds of Dowpon followed later by 3 pounds more gave good control of
grasses with no effect on cane yields. Experiments now in progress indicate that
three applications of 3 pounds each, 3 to h weeks apart, or 5 pounds followed by two
applications of 2.5 pounds each controlled grasses efficiently. For good grass con-
trol when using 2.5 or 3 pounds of Dowpon it is absolutely necessary to spray when
the grasses are very small and to repeat the treatment about 25 days later. Grasses
half grown or more mature are difficult to kill even with 5 pounds of Dowpon. Mix-
tures of Dowpon and 2,4-D amine can be used for the control of weeds and grasses,
(To make this mixture, dissolve the Dowpon in water, then add the 2,4-D) although
the effectiveness of Dowpon appears to be slightly decreased in this case. However
the overall control of weeds and grasses is good. Mixtures of Dowpon and Karmex W
should not be used because such mixtures generally reduce the yield. Dowpon will
give better kill than TCA of grasses after they have emerged.
1/ The research from which the suggestions on weed control are derived was con-
ducted in cooperation with United States Sugar Corporation and was supported
in part by grants from this Corporation.
B- When to apply- Herbicides for pre-emergence weed control should be applied when
the soil surface is moist. For post-emergence weed control spray early, when the
weeds are very small (barely visible). Better kill is obtained when the weeds are
A rain shortly after application of 2,h-D and Dowpon will decrease the kill-
ing action of these chemicals. A rain or moist soil surface is necessary for best
kill when using Karmex herbicides and TCA.
If possible apply the Karmex herbicides, Dowpon and TCA when the cane is
small to prevent the shielding of the weeds by the cane leaves and also to minimize
the light burning of greater cane leaf area sometimes produced by the use of these
Plant cane- Apply 2 pounds of 2,4-D as pre-emergence as soon as the soil becomes
settled. If good control is accomplished, delay second application of 2,4-D until
very small weeds appear. If control of weeds is relatively poor, apply a mixture
of 2 pounds of 2,h-D with 2 pounds of Karmex W. The herbicidal treatments can be
repeated up to 3 times.
In land infested with grasses apply 2 pounds of 2,4-D mixed with 20 pounds
of TCA as a pre-emergence treatment. For post-emergence control of grasses 2.5 to
5 pounds of Dowpon can be used. When weeds other than grasses are present, use the
Dowpon in combination with 1.5 pounds of 2,,4-D. When using rates below 5 pounds of
Dowpon,- two or more applications are necessary.
Scratching in the rows should be done only when absolutely necessary.
Stubble cane- Apply 1.5 to 2 pounds of 2,4-D about 15 days after harvest. Repeat '
the treatment with 1.5 pounds 6f 2,4-D as soon as very small weeds appear. However,
if pellitory weeds are present, substitute 2 pounds of Karmex W or DU for the 2,L-D.
A mixture of 2 pounds of Karmex W and 1.5 pounds of 2,4-D will control nearly all
weeds. This mixture will control weeds which are resistant to either one or the
other of the materials when used alone. When grasses are present, apply 2.5 to 5
pounds of Dowpon as directed for plant cane.
One early and shallow cultivation of the middles does not appear to be harm-
ful to the cane.
C- How to apply- Twenty to 60 gallons of water per covered acre seem adequate for
weed control. If the herbicides are applied as bands on the cane rows, make a pro-
portional reduction of chemical and water for unsprayed area.
Use ground equipment only for spraying herbicides. Speed of travel may vary
from 3 to 5 m.p.h. Pressures of 20 to 30 p.s.i. are sufficient for spraying. Flat
spray nozzles (650 angle) 20"' apart in a boom 25 feet long, and delivering 0.3 to
0.6 g.p.m. are sufficient. Recheck the nozzles occasionally; the nozzles orifice
wears out rapidly and discharges too much liquid. The use of 50 mesh suction,line
and nozzle strainers is suggested. The pump should be constructed of a material
which is resistant to the abrasive., action of wettable powder sprays. Agitation
should be provided in the tank in order to maintain an even suspension of the Karmex
Drift and volatility hazards
None of the herbicides named above present a volatility hazard (damage to
sensitive plants by their vapors). However, damage by wind drift especially of
2,4-D, should be avoided. The minimum distance experimentally found safe for spray-
ing 2,h-D amine salt when using ground equipment is I of a mile from a susceptible
crop. Wind velocity should not exceed 10 m.p.h.
Drift damage to susceptible crops growing nearby was not observed when using
Karmex W, Dowpon or TCA. Nevertheless, if'a crop susceptible to these chemicals is
growing adjacent to the area to be sprayed, caution should be exercised by spraying
when the wind is blowing away from the susceptible crop. Then in a cane field lo-
cated less than of a mile from a susceptible crop only Karmex W should be used for
weed control and Dowpon or TCA for grass control. Do not use mixtures of Karmex W
Definition of terms as used in this paper:
Pre-emergence Application of herbicides before the crop appears above the soil
Post-emergence Application of the herbicide after the crop has emerged from the
Weeds Obnoxious plants other than grasses (when used in a restrictive sense).
Grasses Obnoxious vegetation that belong to the gramineae family, such as: crab
grass, Alexander grass, paragrass, etc. (sugar cane and corn belong to this family
Lbs/A Refers to the amount in pounds that is distributed evenly over one acre
(43560 square feet).
'2OQb3~ 41- jD