CHEMICAL WEEDING OF CABBAGE IN MUCK SOILS
V. L. Guzman and E. A. Wolf
This is a Mimeographed Reprint from the
Proceedings of the Eighth Annual Meeting
of the Southern Weed Control Conference
held in St. Petersburg, Florida on Janu-
ary 17, 18 and 19, 1955.
CHEMICAL WEEDING OF CABBAGE IN MUCK SOILS I/
V. L. Guzman and E. A. Wolf
University of Florida, Everglades Experiment Station
Belle Glade, Florida
Weeding cabbage in the drill is expensive whether it is grown in
seed beds and later transplanted, or seeded directly in the field and
thinned to a stand. This is so especially during the early stages of
growth. Weeds growing between rows can be disposed of by mechanical
means efficiently and at low cost if weather conditions permit. How-
ever, during the late summer and fall months when cabbage is seeded the
usually heavy rains may make the use of mechanical equipment difficult
or impossible. Heavy weed growth also seems to create high humidity
conditions about the plants, favoring a more severe disease incidence,
and, in many cases, preventing good coverage of the cabbage plants
with fungicides. This is particularly true in the organic soils of the
Florida Everglades where the rate of growth during the hot rainy season,
especially of well adapted weeds, is very rapid.
The object of this work was to investigate the possibility of us-
ing herbicides for the control of weeds in cabbage growing in muck soils,
The 1 experiments that are briefly summarized in this paper cover a
period of three years, 1952-$L inclusive.
METHODS OF PROCEDURE
The variety of cabbage used in these experiments was Copenhagen
Market 86. The following herbicides, which appeared most promising in
preliminary screening tests, were employed for pre-emergence studies:
N-(3-chlorophenyl) carbamkte (CIPC); disodium 3, 6-endoxohexahydrothalate
(Endothal 3003); 3-p-chlorophenyl-l-l-dimethylurea (CMU); sodium tri-
chloroacetate (TCA); and octachlorocyclohexenone (Oktone). For post-
energence, four herbicides were used: sodium isopropyl xantate (NIX),
CIPC, sodium salt of maleic hydrazide (0IH-O) and sodium a, a-dichloro-
propionate (dalapon). They were applied as an over-all application to
the cabbage plants and weeds.
Concentrations of the herbicides are given on per acre broadcast
basis of active ingredient except for TCA, CMU and NIX, which are com-
mercial grades. The herbicides were applied at a pressure of 25 p.s.i.
in 30 gallons of water per acre except for Oktone and NIX. The former
was applied in 30 gallons of diesel oil and the latter in 90 gallons of
water. The ground was rolled immediately after seeding and prior to the
pre-emergence application of the herbicides, and the weed counts were
taken approximately four weeks later. The treatments in each experiment
were replicated six times. Plots and sub-plots were 30 feet long with
one to three rows.
1/ This work was made possible in part by grants from B. F. Goodrich
Chemical Company and Columbia Southern Chemical Corporation.
RESULTS AND DISCUSSION
Effect of pre-emergence application of various chemicals and rates
on cabbage planted in seed beds under heavy and light rainfall. Table 1
shows type of chemicals, rates of application and their average effects
on stand of cabbage and weeds in two experiments conducted in the fall of
1952. In one experiment under heavy rainfall conditions (9 inches in one
week and 11.68 in three weeks) there was a significant reduction in the
stand of cabbage with CMU, Oktone and TCA. However, if the stand of
cabbage for heavy and light rainfall is combined and analyzed, only CMU
produced a significant reduction of stand. The effects of each herbicide
and its rates vrere reflected also in the growth of the cabbage plants.
The largest plants were from the Oktone treatments. The check plants
were next in size with plants of the following treatments in decreasing
order: Endothal, TCA, CIPC and CiU.
Under heavy rainfall, the hand hoed treatments had significantly
fewer weeds than the chemically treated ones. The opposite was true
under light rainfall (0.39 inches in three weeks), except in the case of
Endothal. This herbicide seemed to have less residual effect upon weeds
than the other herbicides.
TCA gave good control of grass weeds and poor control of broad-leaf
weeds. Oktone and CMU were more specific for broad-leaf weeds and less
for grasses. CIPC was intermediate, giving excellent control of all types
of weeds, especially purslane, Portulaca oleracea L. Endothal gave good
control of all types of weeds, but only for a short period of time.
Table 1. Effect of herbicides applied as pre-emergence sprays on the
number of cabbage plants and weeds under heavy and light rain-
fall (October, 1952).
Treatments Stand of Cabbage Number of Weeds
Blots Sub-plots Rainfall Rainfall
Che-micals Rates (3) lbs/A Heavy Light Heavy Light
Low Med. High
1 CIPC 8 9 10 321 293 30.7** 10.1*
2 Endothal 9 12 15 364 350 35.9** 12.7
3 CMU 0.75 1.0 1.25 198** 276 29.6** 11.6*
U TCA 15 20 25 297* 323 36.2** 11.7*
5 Oktone 8 10 12 237** 374 33.3** 11.6*
6 Check One Two Three 359 321 17.2 15.8
LSD .05 48 NS 7.3 3.2
.01 66 NS 9.9 NS
* Significantly different from check.
** Highly significantly different from check.
The average effects of herbicide rates on the stand of cabbage plants
and weeds are presented in Table 2. The stand of cabbage and the number
of weeds were not affected by any of the treatments under light rainfall;
however, under heavy rainfall the differences are significant; that is,
the higher the concentration of the herbicides the fewer the cabbage
plants. The medium and high rates also significantly decreased the num-
ber of weeds in comparison to the low rates. There were also significant-
ly fewer weeds under light rainfall than under heavy rainfall. This may
be due in part to the germination of fewer seeds under the former condi-
Table 2. Effect of lo medium, and high rates of herbicides on the
number of cabbage plants and weeds under heavy and light rain-
fall (October 1952).
Rates Stand of Cabbage Number of Weeds
Heavy Light Heavy Light
Low / 328** 324 37.0** 12.5
Medium / 291 325 27.4 12.5
High i/ 271 319 27.3 11.5
LSD .05 23 NS 4.2 NS
.01 31 NS 5.6 NS
1/ For rates see sub-plots of Table 1.
** Highly significantly different
Although two experiments are presented here, actually four tests
were conducted on kind and rate of herbicides. The results may be sum-
maried as follows: CHU appeared in most cases to be very toxic to the
cabbage plants. Endothal 3003 was a good selective herbicide for cab-
bage, but its residual toxicity upon weeds was of short duration. Oktone
at rates from 8 to 13 pounds per acre in all cases except one (under heavy
rainfall) did not affect the stand of cabbage plants; furthermore, in many
cases plants treated with Oktone seemed to be larger than those from the
hand hoed check plots. The best rate of Oktone for the control of weeds
in these experiments was 10 pounds per acre. TCA slightly decreased the
size of the cabbage plants, especially at the 25-pound rate, but no per-
manent injury to the plants occurred. Since the stand of the cabbage
plants was reduced with rates of 25 pounds it is suggested that TCA be
tried at 15 to 20 pounds per acre. CIPC stunted the cabbage plants in
most cases, although the control of weeds was good to excellent and the
stand of cabbage at rates of 10 pounds or below was not significantly
reduced (except under conditions of heavy rainfall). At the conclusion
of these experiments the use of 8 to 10 pounds of CIPC was suggested
(in subsequent experiments however, under different environmental condi-
tions CIPC was found to be toxic to cabbage). Under heavy rainfall most
of the herbicides tended to cause some damage to the cabbage plants,
either by affecting their size or reducing the stand.
The yield and quality of marketable cabbage grown to maturity in the
field from seed beds treated with the highest rates of herbicides failed
to show any differences from those of the hand hoed check plants.
Pre-emergence weeding in cabbage seed beds with combinations of two
herbicides. To investigate the possibilities of obtaining better over-
all weed control in fields infested with both grasses and broad-leaf
weeds, two experiments were carried out combining one herbicide specific
for grasses with one for broad-leaf weeds. Of the six combinations
studied, it was found that three were promising. They are: 1 8 pounds
of Oktone mixed with 8 pounds of CIPC; 2 8 pounds of Oktone and 15
pounds of TCA; and 3 8 pounds of CIPC mixed with 15 pounds of TCA. These
three combinations did not significantly affect the stand of cabbage plants
in the seed beds or the yield and quality of marketable heads.
Effect of post-emergence weeding with rates of various herbicides on
cabbage plants and weeds. A month after the cabbage plants were trans-
planted to the field, three rates of NIX and CIPC were sprayed as a
broadcast application over the cro and weeds. NIX gave good control of
most broad-leaf weeds. This was found to be proportional to the amount
used. CIPC controlled the weeds satisfactorily but also caused severe in-
jury to the cabbage plants. The plants never recovered from a shiny,
leathery condition of the leaves that was due to CIPC treatment. NIX also
produced appreciable burnin; of the cabbage leaves to a degree that was
related to the rate of treatment. However, a few weeks later the cabbage
outgrew the damage and appeared normal, though the plants continued
smaller than those of uhe same age in the hoed check plots of an adjacent
Yields of marketable heads are given in Table 3 for three separate
experiments. The only significant difference in yields is to be found in
the CIPC treatments. It appears, however, that NIX and, to a greater ex-
tent CIPC, reduced the yields of cabbage when compared to the yields of
plants of the same age from hand hoed plots in an adjacent experiment
(Table 3). In the case of cabbage treated with CIPC, yield reductions
were due to death of the plants (especially at the highest rates) in addi-
tion to the severe stunting effect of the herbicide, which caused the pro-
duction of non-marketable heads. The burning action of NIX and subse-
quent checking of growth appeared to reduce the sige of the heads and to
be the main cause of yield reduction.
An experiment was conducted in April, 1954 for post-emergence grass
control in cabbage growing in the field. An over-all application of
twenty pounds of dalapon gave better control of grasses than MH-O0 and
NIX. The stunting effect caused by dalapon was very severe, but no death
of the cabbage plants occurred. Experiments with other crops have in-
dicated that lower rates of dalapon are equally effective against grass
weeds and the injury to the cabbage plants also may be reduced, especial-
ly if the herbicide is applied directionally.
Table 3. Yields in pounds of marketable heads from plots weeded with
three rates of herbicides applied broadcast to the cabbage
plants and weeds.
Rates i / Kinds of Herbicides
NIX 1 CIPC/ NIX V
Oct. 17, 1952 Dec. 8, 1952 Dec. 8, 1952
Low 310.2 21$.4** 316.3
Medium 289.6 125.5 335.
High 291.5 119.1 226.0
LSD .05 NS 10.9 NS
.01 15.5 --
Hand hoed check from
adjacent experiment 466.5 382.9 382.9
1/ 10 15 20 pounds of NIX per acre, respectively, for low, medium
2/ 4 6 8 pounds of CIPC per acre, respectively, for low, medium and
m* Highly significantly different.
Combined effect of pre- and post-emergence weeding with herbicides
on cabbage plants and weeds. Four pre-emergence treatments: TCA, Oktone,
CIPC and no treatment were combined with post-emergence of 7.5 pounds of
NIX, 10 pounds NIX and no treatment in a direct seeded experiment of split
plot design. The first NIX application was over all the cabbage plants
and weeds; the second was spot application on the weeds only.
The control of weeds with Oktone was 95 percent, CIPC 80 percent,
and TCA 70 percent of the check (zero control). The cabbage plants were
not injured by pre-emergence weeding with TCA and Oktone, but severe
stunting in growth of the plants and a reduction in stand from 50 to 70
percent occurred with CIPC. TGA gave poor control of broad-leaf weeds.
Oktone controlled all the broad-leaf weeds efficiently. NIX as post-
emergence application controlled all the small weeds, but failed to kill
a few weeds two or more inches tall. This was true of grasses in partic-
ular. It has been found that NIX kills small weeds provided that the air
temperature during spraying is above 700 F and no rain falls for six or
more hours after treatment.
In Table 4 are to be found the yields of marketable cabbage heads
from the plots in which the combined effect of pre- and post-emergence
weeding with chemicals was employed. Because of inadequate stands
caused by CIPC, yields of these plots were not obtained. The cabbage
yield was unaffected by 15 pounds of TCA and 10 pounds of OKtone. NIX
produced a highly significant reduction in the yield of cabbage, mostly
by affecting the size of the heads. V!hether thicker planting could off-
set the reduction in yields due to the NIX treatment, or directional
application of the herbicide could diminish the damage to the cabbage
plants has not yet been ascertained.
Table U. Total yields in pounds of marketable cabbage from plots
treated with both pre- and post-emergence herbicide applica-
tions (January, 1953).
Pre-emergence Post-emergence yields LSD
NIX 7.5/A NIX 10.0/A Cultivated Pre-E Post-E
TCA 15 lbs/A 333.0 330.1 445.3 1108.h
Oktone 10 lbs/A 367.1 345.3 399.4 1111.8
Cultivated 321.3 288,1 U42.2 1051.6
Total yields Post-E 1021.4 963.5 1286.9
Mean Post-E 56.79** 533.57* 71.55 9.49 12.?77
LSD Pre-E .05 ----------- ----------------------- NS
* Highly significant difference compared to cultivated checks.
Two other tests were conducted during 1953 to further check the ac-
tion of CIPC on cabbage. The results indicated again that a 10-pound
treatment with the chemical was toxic, especially if high soil moisture
and low temperatures prevailed during treatment and for a few days there-
after. Lower rates night not have produced injury to the cabbage plants
but the control of weeds would not have been satisfactory.
Effect of various Oktone'" solvents on cabbage plants. D.S.Burgis
of the Gulf Coast Station has expressed the opinion that Oktone in diesel
oil has caused injury to cabbage plants growing in sandy soils. In muck
soils a reduced stand of plants occurred only under heavy rainfall con-
ditions when using Oktone in diesel oil (Table 1). It was impossible to
ascertain if this reduction of stand was due to the solvent, to the Oktone,
or to their combined action. Therefore, an experiment was designed in
which diesel oil, Stoddard solvent, fuel oil No. 2, and kerosene were used
as Oktone solvents and applied as pre-emergence on cabbage. Overhead ir-
rigation equivalent to six inches per week was applied for three weeks
Table 5 gives the stand and the weight of the cabbage plants, which
were not significantly different. It appears that the above solvents of
Oktone are safe for pre-emergence weeding of cabbage in muck soils.
Comparison of liquid and solid Oktone on cabbage plants and weeds. -
Samples of Oktone received in the fall of 1953 were different from those
of previous shipments in that the new samples were fuming and corrosion
of the containers was more severe. The handling of Oktone under these
conditions was somewhat hazardous. The manufacturers made several attempts
to correct this condition in the liquid formulation without much suc-
cess and after several months of research they prepared Oktone in solid
form. Oktone is sold now in granular or flake form of approximately
95% concentration. It is fairly soluble in diesel oil, Stoddard solvent,
fuel oil No. 2 and kerosene at a rate of 4 pounds of Oktone per gallon of
oil. However, it dissolves much more readily in xylol than in any of the
above mentioned solvents.
Table 5, Stand and weight of cabbage plants taken twenty-five days
after treatment with 10 pounds/A of Oktone dissolved in vari-
ous solvents for pre-emergence weed control in muck soil
Solvents Stand Weight in grams
Diesel oil 2274 1300
S. solvent 1860 1440
Fuel oil 2231 1340
Kerosene 2260 1320
Cultivated check 2055 1240
LSD .05 NS NS
This experiment was conducted to determine and evaluate the toler-
ance of cabbage to the herbicidal properties of solid Oktone. The effect
of solid and liquid Oktone, both dissolved in diesel oil, upon cabbage
plants and weeds is presented in Table 6. The stand and size of the
cabbage plants were unaffected by the treatments. The control of weeds
with both the liquid and solid Oktone was significantly better than the
check. The number of weeds was not significantly different between
liquid and solid Oktone treatments. However, there was a more severe
check in growth of the weeds with the liquid formulation. Plots treated
with liquid Oktone appeared slightly cleaner than those treated with
Table 6. Effect of pre-emergence weeding with the original liquid and
the new solid Oktone on cabbage plants (November, 1954).
Treatments Stand of Cabbage Number of Weeds
Liquid Oktone at 10 lbs. 214 10.7
Solid Oktone at 10 lbs. 249 12.5
Check 211 53.0
LSD .05 NS 22.5
.01 NS 32.2
Pre-emergence weeding with Oktone in a clean field vs a weedy field.
The entire field had been prepared for seeding in the usual manner but
had been allowed to stand until the weeds were 2 inches high. Six plots
of the "weedy field" were left untouched, while the remainder of the
field was fitted for seeding. The entire field was seeded, rolled, and
the following day Oktone was applied at zero, 5 and 10-pound rates in a
split plot designed experiment, the "clean field" vs "weedy field" being
the major treatments and the rates the sub-treatments (Table 7). No
differences in stand of cabbage were found among the sub-treatments. A
significantly better stand of cabbage plants was obtained in the weedy
field than in the clean field. Control of weeds was about equally effec-
tive with both 5 and 10 pounds of Oktone and significantly better than
the check. The check plots of the weedy field had to be cultivated due to
size of the weeds, which otherwise would have smothered the cabbage
plants. The control of weeds in the "weedy field" with Oktone was signi-
ficantly better than in the "clean field". The interaction of weed num-
bers between "fieldb"and herbicides is highly significant.
The method of delayed pre-emergence treatment in a "weedy field"
with 5 pounds of Oktone per acre may be efficient and economical to use.
Table 7. Effect of 5 and 10 pounds per acre of Oktone on number of weeds
and stand of cabbage seeded on a "clean" and "weedy" field
Treatments Cabbage Weeds i/
Clean Weedy Clean Weedy Mean LSD
Field Field Field Field Weeds .05 .01
Oktone 10 lbs/A 195 216 20.3 7.5 13.9
Oktone 5 Ibs/A 167 218 24,1 9.6 16.9
Check 176 204 52.8 16.3 34.6
Mean Cabbage 179.7,* 212.7 ................... 20.4 31.9
Mean Weeds ............. 32.4 11.2* .... 15.7 NS
LSD .05 NS NS 4.7
1/ Interaction between fields and rates of chemical on number of weeds
was significant LSD .05 = 6.7 LSD .01 = 9.1
* Significantly different
** Highly significantly different.
In another experiment, a "weedy field" (prepared in identical manner
to the one described above) was treated with 8 pounds of Oktone and an
excellent control of weeds followed. Nine and 34 hours later, cabbage
plants were machine transplanted in this field. No difference in cabbage
stand was found in the Oktone treated plots and the untreated check.
Growth of the cabbage plants appeared normal. No rain fell during the
From 1952 to 1954 inclusive, 14 experiments were carried out on
chemical control of weeds in cabbage growing in muck soils. Rates of
herbicides used in these experiments are expressed in pounds per acre.
Pre-emergence. Twenty pounds of TCA or 10 pounds of Oktone were
the best herbicides for pre-emergence weeding of cabbage and they did not
affect yields. TCA gave good control of grasses. Oktone controlled broad-
leaf weeds and gave fair control of grasses. An application of 8 pounds
of TCA followed by 8 pounds of Oktone was promising for the control of
both broad-leaf and grass weeds. Seeding of cabbage in a weedy field
followed by delayed pre-emergence treatment with 5 to 10 pounds of Oktone
gave better control of weeds than similar rates of Oktone in a field
freshly prepared, planted and treated,
Post-emergence. Application of 10 pounds of NIX resulted in good
control of all types of small weeds, although yields were decreased due
to reduction in size of the cabbage heads.
Pre- and post-emergence combined. Ten pounds of Oktone and 15
pounds of TCA applied as pre-emergence treatments, each in combination
with 7.5 and 10 pounds of NIX applied as post-emergence, gave good control
of weeds. All combinations reduced yields of cabbage significantly,
Pre-transplanting. Excellent control was obtained on plots where
weeds were allowed to germinate and were treated with 8 pounds of Oktone
prior to transplanting. Cabbage transplanted 9 and 34 hours after treat-
ment were unaffected.