SUGGESTED METHODS FOR CONTROL OF WEEDS IN SOME VEGETABLE
CROPS GROWING ON ORGANIC SOILS. (for trial only)
V. L. Guzman
This report contains suggestions derived from experiments
conducted on vegetable crops growing on organic soils dur-
ing the period 1952 to 1956. The suggestions should be
used for trial only on a small scale until the chemicals
have received approval for commercial use by Pure Food
EVERGLADES STATION MIIEO REPORT 56-13
Belle Glade, Florida
May 17, 1956
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SUGGESTED METHODS FOR CONTROL OF 'TEDS IN SOIM VEGETABLE
CROPS GROWING ON ORGANIC SOILS. (FOR TRIAL ONLY)
V. L. Guzman I/
Amounts of the herbicides are expressed in terms of active ingredient on
a per acre basis (covered acre) except for Karmexes, TCA, and Dalapon which are ex-
pressed as commercial grades.
CDAA or CDEC at 4 to 8 pounds and TCB at 3 pounds gave excellent control
of weeds and annual grasses. Karmex W (CMU) at 2 pounds, 2,4-D amine at 2 pounds,
and DNOSBP at 12 pounds have given good results also without reducing yields. Good
moisture at the soil surface is necessary for best weed control.
1. Time and method of 2,4-D application. 2,4-D amine at 0.75 pounds applied over-
all to sweet corn at one inch stage produced good weed control and no reduction in
yields. This chemical could be used as directional application after the corn reach-
es 12 inches in height,
2. Comparison of NIX and 2,4-D applied directionally. Good post-emergence weed con-
trol was obtained with both materials. Some burning of the lower leaves occurred
with NIX at 10 pounds but there was no significant reduction in yield. 0.75 pound of
2,.-D amine per acre was used,
3. Results with Karmex IJ, (CMU), Directional application of 2 pounds of CMU on
plants 15 inches high gave good weed control without reducing yields.
4. Early post-emergence with DNOSBP. Application of DNOSBP at 3 4 pounds per
acre as early post-emergence treatment when the corn plants were in the incipient
two leaf stage gave good weed and grass control without affecting yields,
5. Combining pre- and post-emergence applications. Pre-emergence applications of
DNOSBP at 12 pounds or Karmex W (CMU) at 2 pounds with post-emergence applications
of 0.75 pounds of 2,4-D or NIX at 10 pounds gave good to excellent weed control,
Lettuce and Endive
Ten pounds of CIPC applied as pre-emergence to lettuce after rolling the
ground when the upper layer of soil was relatively high in moisture content at medium
temperature of 680 F, gave a commercial control of weeds until harvest, With endive,
some injury occurred with rates above 10 pounds, A rate of 8 to 10 pounds of CIPC
seemed safe for endive. CDEC at 4 pounds per acre showed promise for pre-emergence
weeding of lettuce and endive.
I/ Assistant Horticulturist, Everglades Experiment Station, Belle Glade, Florida,
- 2 -
Pre-emergence. Four to 8 pounds of CDEC gave excellent control of all
types of weeds for over 6 weeks. Also 15 pounds of TCA or 10 pounds of Oktone were
good herbicides for pre-emergence weeding of cabbage and they did not affect yields,
TCA gave good control of grasses* Oktone controlled broadleaf weeds and gave fair
control of grasses,
Post-emergence. Four pounds of CDEC applied one day after emergence re-
sulted in good weed control with no damage to the cabbage plants. One application
of 7.5 pounds of NIX resulted in good control of all types of small weeds.
Pre- and post-emergence combined. Ten pounds of Oktone or 15 pounds of
TCA applied as pre-emergence treatments, ach in combination with 7.5 and 10 pounds
of NIX applied as post-emergence, gave good weed control. All combinations reduced
yields of cabbage significantly.
Pre-transplanting. Excellent control was obtained on plots where weeds
were allowed to germinate (weedy field) and were treated with 8 pounds of Oktone
prior to transplanting. Cabbage transplanted 9 and 34 hours after treatment were
Pre-emergence in seed beds. MC-2 (98% methyl bromide and 2% chloropicrin)
fumigation at one to two*" pounds per 100 square feet gave excellent control of weeds
as well as nematodes and soil-borne diseases. The celery should be seeded no sooner
than 4 days after the fumigation covers are removed.
Pre-transplanting. CDAA (Trade name RANDOX) or CDEC at 8 pounds applied
just before transplanting controlled weeds efficiently.
Post transplanting. CDAA or CDEC at 8 pounds applied just after trans-
planting the celery and followed by overhead irrigation resulted in excellent weed
control* Ten pounds of CIPC also gave good weed control when used during cool
Directional application of 40 gallons of Stoddard Solvent, or 4 pounds of
CLEC, or CIPC in solvent gave good weed kill and also lasting effect in the soil
when using the two latter mixtures,
* Research with sweet corn and certain other vegetable crops was done in coopera-
tion with E. A. Wolf
Wr Two pounds of MC-2 is recommended for best control of diseases* (R. S. Cox)
Table 1. Suggested Methods of Weed Control (For trial onlyM'")
Summary of the Best Herbicides and Rates of Application in Some Vegetable Crops Growing on Peat and Muck Soils at the
Everglades Experiment Station. Amounts are of actual active ingredient (except for Karmex W, TCA and Dalapon which
are expressed as commercial grades) on a broadcast basis for one acre in 30 gallons of water solution,
Predominate Herbicides and Rates
Crop type of weed PRE-IEIS ...E... POST-EERGENCE
Beans Broad leaf DNOSBP*- 9 to 12 lbs.
DNOSBP 3 lbs. applied just when the
beans are breaking through, but not
yet above ground.
Cabbage Broad leaf CDEC I to '.8 3bs.
Cauliflower Oktone 8 to 10 lbs. in diesel oil NIX 7.5 Ibs.(one application) in 90 gals. water
Collards Oktone 5 Ibs. in diesel oil as delayed directionally. Some temporary burning of the
Broccoli Pre-E in a weedy field. leaves occurred.
CDEC^ 4 to 8 Ibs. Spot treatment with 5 Ibs, dalapon in 60 gals.
Grass TCA 15 lbse of water.
CDAA or CDEC'"' 4 to 8 Ibs.
TCB 3 lbs.
DNOSBPF 9 to 12 Ibs.
Karmex W (CIU) 2 lbs.
2,t-D 2 Ibs.
CDAA or CDECG 8 Ibs.
TCB 3 Ibs.
DNOSBP 3 to Ilbs. applied at incipient 2 leaf stage
2,4-D Amine 0.75 Ibs. overall up to 1" high and
directionally when plant 12" high up to
NIX 10 lbs, applied directionally without touching
CII'L 2 lbs, directionally applied,
DNOSBP 3 to 4 lbs. at incipient 2 leaf stage
Lettuce Broad leaf CIPC 10 Ibs. overhead irrigation after CIPC 6 lbs, temporary burning of the leaves and
and grasses application of CIPC helps to con- some reduction in yields occurred. .'.
trol weeds, .,. ... .
f ...._____CDEC"' 4 lbs. (promising)*. 0 Ibs. of 20% pelletized CIPC.
Endive Broad leaf CIPC 8 to 10 lbs, I/ Same as for lettuce.
_and grasses __
Table I. Continued
Pepper Broad leaf CDEC 4 lbs. (promising), Directional only to the base of the pepper plants
Oktone 10 Ibs. in diesel oil when weeds are very small.
Oktone 5 lbs. in diesel oil as delayed NIX 7 Ibs. in 90 gals. water
Pre-E. in a weedy field .
Grass TCA 10 lbs. Dalapon or TCA 10 Ibs, as spot treatment
CIEC -. lbs, (promising
Eggplant Broad leaf Oktone 10 lbs. in diesel'oil
___Grass CIEC lbs. (promising). Same as for pepper,
Onions Broad leaf CIPC 10 to 12 lbs. 2,5% Sulfuric acid
and grasses 2,4-D Amine 2 lbs. Potassium cyanate 12 lbs,
CDEC 4 to 8 lbs MNIX 10 lbs, in 90 gals, of water
_________5___________0 Ibs./A of 20% pelletized CIPC
Carrots Broad leaf CIPC 10 to 12 lbs./A Stoddard Solvent 50-70 gals./A
and grasses CDEC 4 to 8 lbs. (promising) CIPC 4 lbs./A in 30 gals. of Stoddard Solvent
CIPC 6 Ibs./A in 30 gals. of water (as pre-
emergence to weeds)
50 Ibs./A of 20% CIPC pellets.
Parsley Broad leaf Same as for carrots
For celery seed beds:
MC-2 at the rate of 1 lb. per 100 square
feet (decreases stand but the celery
plants appeared healthy and the control
of weeds was good)
Pre-transplanting: 8 Ibs. of either CEEC or CDAA
Post-transplanting: 8 Ibs. of CDAA or CDEC followed
by overhead irrigation. Directional applications
of 40 gals. of Stoddard solvent alone or mixed with
4 lbs. of either CDAA, CDEC or CIPC
50 Ibs./A of 20o CIPC pellets.
DNOSBP (Dinitro-0- secondary butyl phenol) (Trade Names Sinox PE, Pre-emerge) contains 3 lbs, active ingredients per gal.)
C- CDAA is called RANDOX in the trade. CIEC is 2-chloroallyl diethyldithiocarbamate. (Monsanto)
*w3' Many of these chemicals have not been placed on the approved list by Pure Food and Drug. Please consult your County
Agent or Experiment Station before using them commercially for weed control,
COIMENTS Pre-emergence means the application of chemical anytime after seeding but before emergence. Delayed Pre-E. in
a weedy field means to seed the crop in a field in which the weeds are about 1 inch tall and then apply the herbicide.
(Rolling means to pack or smooth out the soil by the use of a roller). Post-emergence is the application of herbicides
when the crop is already up. Best post-E. weed control is obtained when herbicides are applied to very small weeds,