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Group Title: Mimeo report - Belle Glade, Florida Research and Education Center ; EV71- 12
Title: Weeds and weed control in Florida sugarcane
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Permanent Link: http://ufdc.ufl.edu/UF00067599/00001
 Material Information
Title: Weeds and weed control in Florida sugarcane
Series Title: Mimeo Report
Physical Description: 15 p. : ; 29 cm.
Language: English
Creator: Orsenigo, J. R
Agricultural Research and Education Center, Ona
Publisher: Agricultural Research and Education Center
Place of Publication: Belle Glade Fla
Publication Date: 1971
 Subjects
Subject: Sugarcane -- Florida   ( lcsh )
Weeds -- Control -- Florida   ( lcsh )
Genre: non-fiction   ( marcgt )
 Notes
Statement of Responsibility: J.R. Orsenigo.
General Note: "September 1971."
General Note: Caption title.
Funding: Belle Glade AREC mimeo report ;
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Bibliographic ID: UF00067599
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 65637669

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Full Text
SHU E LIBRARY



Es A RICULTURAL RESEAH A EDUCATION CENTER
I.F.A.S. U EM %F LARIDA

MIMEO REPORT EV71-12 SEPTEMBER 1971
1/
WEEDS AND WEED CONTROL IN FLORIDA SUGARCANE-
2/
J. R. Orsenigo-

WEEDS

Weeds are an obvious problem. They may influence crop production in
many ways, but competition for light, nutrients, space and water represents
their major effect on sugarcane locally.

Unitl recently, the principal weeds affecting Florida sugarcane were
annuals, mainly grasses like Brachiaria plantaginea, Alexandergrass: Digitaria
spp., crabgrasses; and, Eleusine indica, goosegrass. The important broadleaf
weeds were annuals readily controllable with timely applications of chlorophenoxy
herbicides. The only common winter-spring broadleaf,Parietaria floridana,
pellitoryweed, varied in local importance anc could be controlled economically
when necessary.

Sugarcane weed flora has shifted perceptibly since 1965. Panicum
adspersum, an annual grass has become common. It is not easily distinguished
from Alexandergrass during seedling and juvenile stages and it is not readily
controlled by Ametryne.

The most important recent change is the infestation of perennial grasses
in sugarcane fields throughout the area. The dominantspecies is Pennisetum
purpureum, Napiergrass (falsely called maidencane). Napiergrass is propagated
by seed and stalk sections and may have been "planted" in some fields started
with machine-harvested seedcane.

Considerable confusion revolves around the Sorghum species. It is doubt-
ful that Sorghum halapense, johnsongrass, occurs widely or in local concen-
trations in the Florida sugarcane area. Plants which resemble johnsongrass,
with erect panicles and rhizomes, probably are interspecific hybrids of an
original johnsongrass population with sudangrass. Plants which resemble
johnsongrass but lack rhizomes and have drooping panicles probably are
Sorghum sudanense, sudangrass. The free hybridization of Sorghum species
under field conditions would account for the composition, distribution and
varying characteristics of the local infestations.




1. Originally presented at the First Annual Meeting of the Florida Division-
American Society of Sugar Cane Technologists at Palm Beach, Florida, on
15 October 1970 and originally published in the Proceedings of that meeting.

2. Professor (Plant Physiologist), University of Florida, Institute of Food
and Agricultural Sciences,Agricultural Research and Education Center, Belle
Glade, Florida 33430.









Several Panicum species, fall panicum, guineagrass and witchgrass,
occur throughout the local sugarcane area in several limited locations and
with giant foxtail and coast cockspur, represent serious potential annual
perennial infestants.

Weed plants are responsive to the same ecological stimuli, especially
moisture and temperature, which influence crop plant growth. Weed populations
are not static and shift for adaptive survival under environmental pressure
from natural sources like climate, diseases, insects and other plant pests
and from applied sources like crops, cultural changes and chemical and
mechanical control practices. A mixed population of spiny amaranth and
nightshade may be converted to nightshade after repeated 2,4-D applications
minimize or eliminate the amaranth. Populations of 2,4-D-resistant purslane
and dalapon-resistant bermudagrass have developed under field spray programs.
Weed shifts tend toward more aggressive, more competitive, chemical-tolerant,
perennial grasses; populations more difficult to control.

Problem weed species must be identified and control programs must relate
to the weed in its ecological habitat. Control programs are directed to
annual and perennial weed (broadleaf, grass, sedge or mixed) populations
using either preemergence or postemergence operations against the reproductive
organs, seed or vegetative propagules, or seedling to mature plants.

The shift in local sugarcane weed flora probably was hastened by the
rapid, widespread expansion of the industry by new, inexperienced growers
over a wide geographical area and by inferior field and ditchbank sanitation.

WEED CONTROL METHODS

Preventive
Good management includes all sanitation practices which prevent entry
of weed seed and weed plants into cropped areas. Wind and water-borne seed
cannot be regulated, but the grower can control movement of plants, soil,
equipment and supplies onto his land.

Cultural
Timely off-season tillage, fallowing and flooding followed by'good
seedbed preparation help to reduce weed problems. Flooding may be a mixed
blessing in fields heavily infested with water-tolerant seed and in poorly
prepared and inadequately flooded fields.

Mechanical
Tillage effectively controls many weeds, especially small annual seed-
lings, but must be timed for optimum weed control with minimal crop damage.
Mechanical methods provide only transitory weed control ; weed seed may begin
to germinate immediately after cultivation when conditions are favorable.

Manual weed control, with hand hoes, can require 50 to 100 man-hours per
acre in grass-infested fields. A short labor supply and increasing labor costs
have long precluded manual weed control in all but exceptional circumstances.









In the plant crop, the traditional ridge-and-furrow planting system
with disc and scratch cultivators is yielding to flat culture and more
economical scratch and rolling cultivators. No cultural problems have
been observed in more than 15 years of flat-planting in herbicide experi-
ments. It is doubtful that effective in-row implements can be developed to
supplement inter-row rotary tillage in ratoon crops.

Chemical
The options available for weed control are increased greatly by chemical
herbicides. Herbicide programs may be adapted for short or long duration,
foliage or soil treatment, quick contact or slow systemic action, selective
or non-selective response and spray or granular application.

Chemical weed control is a complex, interacting biological-chemical"
system.which includes the crop, the specific weeds, the specific herbicide
and the plant environment. The objective of chemical weed control is to use
a chemical or its metabolites to kill weeds without economic harm to the crop
(or the environment). All chemicals and methods of application require a
high degree of selectivity, the differential response of weeds and crops.
Herbicide performance is affected by: dosage rate, time and method of appli-
cation, climate and soil. Preemergence and preplanting herbicides are used
as preventive insurance against anticipated weed problems and are more expen-
sive. Postemergence herbicides are usually applied as foliar sprays in more
economical corrective treatments for existing weed problems.

FLORIDA HERBICIDE EVALUATIONS

Herbicides useful in sugarcane production in other areas of the world
may not be effective under the climatic and cultural conditions and the high
sorptive capacities of Florida's organic soil. The following general pre-
and postemergence methods with established varieties are used to develop
Florida recommendations at the'Everglades Experiment Station. Candidate
herbicidal chemicals are screened for weed control performance and annual
field and vegetable crop response in primary evaluation trials. Chemicals
which effectively control weeds, especially annual grasses, are then tested
in primary sugarcane evaluations to confirm weed control activity and to
assess sugarcane tolerance. The most promising chemicals are placed in
secondary evaluation trials to observe crop stand and growth responses
(and sometimes yield) and weed control duration. Chemicals with promise
of commercial development are tested in yield trials using replicated,
4-row 1/50th acre plots which permit accurate determination of sugarcane
stand, growth, yield and juice quality. Ratoon responses are evaluated
and herbicidal treatments may be repeated on the same plots for several
ratoons. Consistently superior chemicals with commercial labels or pros-
pects of commercial labelling for sugarcane are tested in replicated one
or two acre herbicide demonstration plots in grower fields for commercial
harvest and final estimation of grower utility.

The program is sufficiently flexible to permit adding desirable chemicals
at an intermediate step or to permit by-passing an early stage of the evalua-
tions.









The experimental results reported in this communication are not intended
to be nor should be construed as recommendations. Effective recommendations
and specific details for sugarcane weed control are available in publications
of the Everglades Experiment Station, the USDA Summary of Registered Pesti-
cide Uses and the produce labels for herbicides "cleared" for sugarcane.

Preemergence small-plot experiments:
Typical results of replicated small-plot experiments are summarized
in Tables 1, 2, and 3. It is difficult to simulate commercial cultivation
in 0.01 and 0.02 acre plots with powered equipment because space is in-
sufficient to develop ground speed necessary for good cultivation. Hand-
weeded control plots are hand-cleaned with scuffle hoes supplemented by spray
applications of chlorophenoxy herbicides. Hand operations are less rigorous
and less damaging to cane than commercial cultivation and do not reflect
yield-reducing injury from cultivation equipment.

Fenac was applied preemergence and/or postemergence to the same plots
of Cl. 41-223 sugarcane planted in twin-row beds for three successive crops.
Better than commercially acceptable control of annual grass and broadleaf
weeds was recorded. Cane yield did not differ among the chemical and control
treatments (Table 1).

Other preemergence herbicide programs were applied in successive crops
of Cl. 41-223 sugarcane planted in twin -row beds. All chemical treatments
provided acceptable annual grass and broadleaf weed control and did not
differ in yield from the control (Table 2).

The response of C.P. 50-28 sugarcane to four successive applications
of preemergence herbicides is reported in Table 3 in pounds sugar per acre
per month. The four crops were grown over a 47-month period. Sugar yield
on a monthly basis is an effective means of comparing production efficiency.
The chemical treatments reported effectively controlled annual grass and
broadleaf weeds. Yields, as tonnage of cane or sugar per acre, did not
differ significantly over the first three crops.

Results of the foregoing three experiments demonstrate that preemergence
herbicides may be used to control annual grass and broadleaf weeds in sugar-
cane on organic soil without harmful effect on yield. Occasionally, late-
season application of chlorophenoxy herbicides may be needed for clean-up
of broadleaf weeds in preemergence plots. Fenac has consistently provided
partial control of annual grass weeds in the ratoon crop following treatment.

Postemergence small-plot experiments:
Tables 4,5,6, and 7 summarize typical small-plot trials with herbicides
applied broadcast overall to emerged cane and weeds. General postemergence
herbicides are applied at lower, more economical, rates than preemergence
herbicides. But, a high degree of selectivity is needed to control weeds
without injury to the crop.

Atrazine, Fenac and Karmex combination treatments applied to the same
plots in three successive crops of Cl. 41-223 sugarcane planted in twin-row









beds are summarized in Table 4. Karmex provided the most complete control
of annual grass and broadleaf weeds but reduced crop yield significantly
or highly significantly each year. The Fenac and Atrazine combinations
afforded better than acceptable control of annual grass and broadleaf weeds
without affecting cane tonnage or juice quality.

Installation and management were similar for experiments with C.P.
50-28 sugarcane reported in Table 5 and Table 6. In one experiment, Fenac
was applied preemergence to all plots in the first and second ratoons. In
the third and fourth ratoons, preemergence-applied Fenac was continued in
one treatment while various combinations of Fenac and 2,4-D were tested post-
emergence to cane and weeds. Both the preemergence and postemergence appli-
cations were effective against annual grass and broadleaf weeds but the
precmergence t-eatment repeatedly outyielded the postemergence treatments
(Table5).

Similarly, in another experiment, Limit was applied preemergence in the
plant crop and Atrazine + Randox was applied preemergence in the first
ratoon. In the third and fourth ratoons, Atrazine + Randox was continued
in a preemergence treatment and various combinations of Atrazine + 2,4-D
+ surfactant were applied postemergence in other treatments. All treat-
ments controlled annual grass and braodleaf weeds but the preemergence
combination repeatedly outyielded the postemergence applications (Table 6).

The role of surfactants in postemergence herbicidal activity has been
evaluated repeatedly. Results are.clear-cut and dramatic on some occations.
Table 7 illustrates the response of C.P. 59-73 sugarcane to the same combina-
tions applied in the plant and first ratoon crops. Weed control was equivalent
in all combinations. Reduced plant damage and slightly higher yields were
recorded for combinations including ACL 209 or ACL 210 surfactants. ACL 209
appears to be the "safest" surfactant tested. It may not be possible to
predict a general optimal combination of herbicides and surfactants because
performance is related to weed population, cane variety, rate of growth,
season of year, dosage rates and other inconstant factors. Combination test-
ing will continue to determine useful combinations which will control weeds
without injuring cane.

Postemergence herbicide evaluation experiments have illustrated that
certain combinations will effectively control annual grass and broadleaf
weeds with no or minimal injury to sugarcane. Constituents of the combina-
tions and their dosage rates determine safety. Postemergence herbicides
should be applied off sugarcane foliage and directed to weed vegetation.
Surfactant levels should be kept in the range 0.25 to 0.50 % v/v.

Semi-commercial scale experiments:

Experiments to simulate commercial herbicide usage have been conducted
with plots 6- or 12-rows wide by one-quarter mile long (1 to 2 acres) or
one-fifth acre plots. Three.or more replications have been installed in
grower's fields. Plots are cut by commercial crews and loaded and handled
with conventional equipment.









Results of a typical trial with Cl. 41-223 sugarcane with largely
recommended practices are summarized in Table 8. All chemicals afforded
commercially acceptable annual grass and broadleaf weed control. The pre-
emergence herbicides were slightly superior to the postemergence treatments
especially in control of annual grasses. Cane tonnage and juice quality
did not differ among these programs.

The effect of rate and method of Ametryne application was evaluated in
adjacent plant and first ratoon fields of Cl. 49-198 sugarcane (Table 9).
Semi-directed spray applications off the cane foliage effectively controlled
annual grass and broadleaf weeds without effect on cane tonnage or sugar
yield. High-rate semi-directed spray application caused visible damage to
cane foliage and subsequent reduction of yield. Broadcast overall applica-
tion of Ametryne, alone or in combination with Atrazine, 2,4-D or surfactant,
injured the cane plant and reduced yield. Results with this variety parallel
those in most other experiments: Ametryne may be used safely in low-dosage,
semi-directed sprays which avoid wetting crop foligae.

Napiergrass control experiments:
Napiergrass populations compete vigorously with sugarcane; stools
ratoon along with sugarcane following harvest and grow at a rate equal to
or slightly faster than sugarcane from March into summer. Stool area can
increase rapidly by lateral growth until closein. Napiergrass seed
apparently require warmer weather for germination, seedling growth and stool
establishment. Seedling populations start to develop before closein and
continue into summer. Napiergrass and sugarcane populations are interrelated:
cane fields with good stand and vigorous growth appear to maintain a com-
petitive advantage while cane fields with inferior stand and growth appear
readily dominated by Napiergrass. Efficient herbicide evaluation is hindered
by random distribution of Napiergrass populations in sugarcane fields.

Herbicides have been evaluated for fence-row and ditchbank weed control.
Promising chemicals from these trials have been tested in several non-
replicated "infeild" experiments. The relationship between Napiergrass
populationand cane tonnage within one field illustrated in Table 10 con-
forms to common observation that high Napiergrass populations denote low
cane tonnages.

Napiergrass stools present in Cl. 41-223 sugarcane in April and May
were treated with foliar-sprays of Ametryne. Cane tonnage at havest appeared
to be related to Napiergrass stool populations (Table 11).

Both soil sterilant and foliar-absorbed herbicides were employed in a
non-replicated trial (Table 12). Chemicals were applied two or three times
as spot-treatments in March, April or May to Napiergrass stool regrowth in
a ratoon field of C1. 41-223 sugarcane. Soil sterilant chemicals, with the
exception of Pramitol granules, were applied at the rate of 5 to 10 stools
per gallon solution; foliar spray chemicals were applied at the rate of 10
to 15 stools per gallon solution. Stools which survived an early treatment
were retreated during subsequent applications. It is difficult to assemble
firm conclusions from an experiment such as this one: there was no replica-
tion, Napiergrass stool infestation was not uniform, and there was no control
over a summer seedling infestation of Napiergrass. Never-the-less, it is
apparent that reduced cane tonnages were associated with high Napiergrass pop-









ulations at harvest and with certain chemicals which injured ratooning sugar-
cane. These experiments illustrate the three-fold or greater increase in
Napiergrass stool population between close in and harvest.

SUMMARY
Weed competition is a common, obvious problem in sugarcane culture in
Florida. In recent years, the weed flora has begun to shift from mainly
annual grasses to a population which includes more hardy annual and perennial
grasses. The shift has accompanied the expansion of the industry and inferior
sanitation practices. In-field weed control programs apparently have had
little effect on the floral shift. Both preventive and corrective weed
control programs are available and most commercial sugarcane growers use
a combination of methods, i.e., land tillage, flood fallow, mechanical
cultivation and herbicides. Florida herbicide recommendations are de-
veloped in a stepwise process from small-plots to simulated commercial
field plots. Effective pre- and postemergence weed control programs
have been recommended and reported elsewhere. The largest immediate weed
problem is an effective, selective control for Napiergrass and other hardy
annual/perennial grasses which have begun to infest sugarcane fields.

ACKNOWLEDGMENTS

The sugarcane weed control experimentation reported herein was made
possible through the generous cooperation of: Florida Sugar Corporation
(Agriculture Department), Okeelanta Division-Gulf and Western Food Products
(Research Department), Sugar Cane Grower Cooperative of Florida (Agriculture
Department), and United States Sugar Corporation (Agriculture and Research
Departments).











Table 1. Yield response of C1. 41-223 sugar cane planted in twin-row
beds on organic soil to preemergence-applied Fenac.


Herbicide and Rate lb./A ai
Handweeded control
Fenac, 6 lb.
Fenac, 9 lb.
Fenac, 6 lb. delayed
Fenac, 9 lb. delayed


Plant
62.6
57.6
57.8
60.3
58.9


Tons Cane Per Acre
First R. Second R.
56.8 42.1
54.1 42.0
53.1 49.6*
49.2 42.8*
49.2 41.8*


NB. Two feet between rows, 10 feet between bed centers. Herbicides broad-
cast overall preemergence to weeds. Ratoon and delayed treatments
broadcast over cane. Asterisk (*) for second ratoon indicates 2
postemergence applications of (Fenac 2 + 2,4-D 1 lb.).


I











Table 2. Yield response of Cl. 41-223 sugarcane planted in twin-row beds on organic soil
to preemergence herbicides.


Plant crop
Herbicide and Rate/A

Handweeded control
Limit, 2 gpa
Randox, 12 lb.
Randox, 10 lb., no irrig.
Randox, 10 lb. 1/2" irrig.


Tons cane/A

58.7
56.5
58.8
56.9
55.8


Ratoon Crops
Herbicide and Rate/A

Handweeded control
Limit 2 gpa
Randox, 12 lb.
Atrazine 4+Randox 6 lb.
Ramrod, 10 lb.


First
Tons cane/A

47.9
46.9
48.8
48.1
51.9


Second
Tons cane/A

44.7
40.4
39.5
43.6
48.1


NB Two feet between rows, 10 feet between bed center. Treatments broadcast overall
preemergence to weeds. Ratoon sprays covered emerged cane foliage. Limit = a
mixture of Randox 4 + 2,4-D 1 lb/gal. Rates ib lb/A ai.










Table 3. Sugar yield responses of C.P. 50-28 sugarcane to annual preemergence
herbicide application on organic soil.


Herbicide & Rate lb/A ai
Handweeded control
Fenac, 6 lb.
Fenac, 9 lb.
Limit, 3 gpa
Ramrod, 12 lb.


Pounds Sugar per Acre per Month
Plant First R. Second R. Third R.
624 646 897 487
609 695 954 551
604 652 974 598*
578 649* 974# 543#
589 654* 903 445


NB. Limit = a mixture of Randox 4 + 2,4-D 1 lb/gal.
*= Only chlorophenoxy herbicides applied during this crop.
# = Atrazine 4 + Randox 6 lb applied these ratoons.


Table 4. Yield response of C1. 41-223 sugarcane planted in twin-row beds on
organic soil to postemergence-applied herbicides.
Tons Cane per Acre
Herbicidal & Rate Ib/A ai Plant First R. Second R.

Handweeded control 57.5 53.7 41.1
Atrazine 0.8+2,4-D,1/2+S 58.6 53.5 39.6
Karmex 0.8+2,4-D,1/2+S 52.3 33.7 22.7
Fenac 2 + 2,4-D 1 61.4 52.1 38.9


NB. Two feet between rows, 10 feet between bed centers. Treatments
applied twice per crop, broadcast overall to cane and weeds.
S = 1/2% v/v surfactant.












Table 5. Yie! response of C.P. 50-28 sugarcane to annual herbicide
application on organic soil.


Plant Crop
Fenac 9 lb/A
preemergence


37.0 TCA
35.6
33.9
37.9
36.9


1st Ratoon
Fenac 6 lb/A
preemergence


52.2 TCA
53.5
53.6
54.3
55.6


2nd Ratoon


Fenac
*Fenac
*Fenac
*Fenac
*Fenac


TCA 3rd Ratoon


6
1+2,4-D 3
1+2,4-D 2
2+2,4-D 2
2+2,4-D 1


54.6
49.4
50.6
50.0
49.9


Fenac
*Fenac
*Fenac
*Fenac
*Fenac


6
1+2,4-D
1+2,4-D
2+2,4-D
2+2,4-D


* = Combinations of fenac and 2,4-D applied twice, postemergence, broadcast over-
all to sugarcane and weeds. Rates in lb/A ai.



Table 6. Yield response of C.P. 50-28 sugarcane to annual herbicide application
on organic soil.


Plant Crop
Limit 2 gpa
preemergence i,

27.7 TCA
28.8
28.2
29.2
30.3


1st Ratoon
Atrazine 4
Randox 6 Ib
preemergence 2nd Ratoon


52.9 TCA
52.7
53.6
53.5
53.1


Atra
*Atra
*Atra
*Atra
*Atra


TCA 3rd Ratoon


4 + Rand 6
+2,4-D 1/2
+2,4-D 1
+2,4-D 1 1/2
+2,4-D 2


NB. Combinations of atrazine and 2,4-D applied twice, postemergence, broadcast
overall to sugarcane and weeds. Rates in lb/A ai.

= Atrazine 0.8 Ib + 2,4-D + surfactant 1/2% v/v.
** + Atrazine + 2,4-D 0.75 Ib + surfactant 1/2% v/v.


TCA


27.8
23.7
23.8
23.7
25.6


57.4
52.8
53.5
52.3
51.7


Atra
**Atra
**Atra
**Atra
**Atra


4+Rand 6
0.8+2,4-D
1.6+2,4-D
2.4+2,4-D
3.2+2,4-D


TCA


33.1
30.6
30.0
32.1
31.2


___









Table 7. Influence of surfactant in Atrazine 2,4-D combinations on C.P. 59-73 sugarcane response.


Hcrbicial Treatments

Atrazine + 2,4-D + ACL 209

Atrazine + 2,4-D + ACL 210

Atrazine + 2,4-D + X-114

Atrazine + 2,4-D + Surf WK


Number
Dead
Heart

0.4

2.2

24.4

20.0


Cane
Toler-
ance

92%

95

85

82


Plant CroP
Stalk
Length
cm.

180

184

178

184


Cane
Yield
TCA

50.4

S51.5

48.2

49.7


-Sugar
Yield
lb/plot

195

199

187

190


First Ratoon
Stalk Cane Sugar
Length Yield Yield
cm. TCA lb./plot


37.2

36.8

36.5

35.8


124

117

111

117


NB. Atrazine 0.8 lb. + 2,4-D 0.5 lb./A ai + surfactant 1% active v/v applied in 30 gpa water.













Table 8. Response of Cl. 41-223 sugarcane to herbicide programs under
semi-commercial conditions.


Plant Crop
Herbicide and Rate/A ai


Cultivation + 2,4-D & 2,4-5-T

PRE Fenac 9 + 2,4-D 1 Ib

PRE Eptam 5 1/2 + 2,4-D 1 1/2 lb

PRE Atrazine 4 + Ramrod 6 1/2 lb

POSO Atrazine 1 + 2,4-D 1/2 Ib + S

POSO Atrazine 1 + 2,4-D 1/2 lb +**

POS* Ametryne 1/2 + 2,4-D 1/2 lb

POS* Dalapon 3 + 2,4-D 1 1/2 Ib


TCA

42.7

44.6

43.7

43.9

41.8

42.5

40.7

39.0


First Ratoon
Herbicide and Rate/A ai


PRE Atrazine 2.1 + Ramrod 4.8 lb

POSO Fenac 1 1/2 + 2,4-D 1 lb

POSD Ametryne 1/2 + 2,4-D 1/21b +S

POSD Dalapon-M 4 + 2,4-D 1 1/2 lb

POSO Atrazine 1 + 2,4-D 1/2 Ib + S

POSO Atrazine 1 + 2,4-D 1/2 lb +**

POSD Ametryne 1/2 + 2,4-D 1/2 Ib + S

POSD Dalapon 4 + 2,4-D 1 1/2 lb


NB. PRE indicates a single preemergence application at planting or ratooning.
All postemergence treatments applied twice. POSO = Postemergence overall
to cane and weeds. POSD = postemergence directed sprays to wet weeds but
avoid most cane foliage. POS* = first application overall and second
application directed. ** = Sun i1E phytobland oil at 2 gpa. S = sur-
factant X-100 or X-114 at 1/2% v/v.


TCA


29.6

34.4

31.5

32.9

29.3

32.2

29.0

31.5








Table 9. Plant and ratoon Cl. 49-198 sugarcane and weed response to Ametryne applied postemergence
in semi-commercial-scale replicated plots.

Postemergence Combinations Cane Tolerance Weed Control Tons Sugar/Acre

Amet- + Atra- + 2,4-D + X-114 Plant Ratoon Plant Ratoon Plant Ratoon
ry3 zine amine %

Semi-directed, skid_applied

1/2 1/2 1/2 92% 87% 91% 97% 5.33 5.22

1 1/2 1/2 81 78 97 100 5.08 4.76

2 1/2 1/2 56 65 97 100 4.68 4.42

Broadcast overall

1/4 1 1/2 1/2 84 92 87 100 4.76 4.79

1/2 1 1/2 1/2 72 78 91 100 4.64 4.31

1/2 1/2 1/2 69 75 91 100 4.53 4.47

1/2 -- 1/2 72 75 91 100 4.65 4.21
/2 -- -- -- 84 81 87 91 4.97 4.59
-- 1 1/2 1/2 96 96 94 97 5.24 5.13

----------------------------------------
-------------------------------------------------------------------------------------------------

NB All treatments applied twice. Rates in Ib/A ai except surfactant in % v/v.
Plots 6 rows wide by one-quarter mile long, replicated 4 times.











Table 10. Relationship between Napiergrass populations and yields of
Cl. 41-223 sugarcane in untreated control plots.


Plot Designation

A 8
B 13
C 18
D 24


Napiergrass Stools
in Spring at Harvest

30 223
138 949
151 1162
311 795


NB. Plots 4 rows wide x 1/4 mile long.


Table 11.


Relationship between Napiergrass populations and yield of
Cl. 41-223 sugarcane in Ametryne treated plots.


Herbicidal treatment

"Ametryne 80W"
at 40 lb product
per 100 gal water
as foliar sprays
in April and May


Napiergrass Stools
at Treatment at Harvest


Pounds
Cane/Plot
25,520
15,660
10,820
12,500


Pounds
Cane/Plot


48,520
39,880
32,360
30,680
37,380


__







Table 12. Napiergrass and Cl. 41-223 sugarcane response to soil-sterilant and foliar-spray spot application
of herbicides for Napiergrass control.
Date Applied Number stools at Pounds
Herbicide and Rate of Application 22Mar 23 Apr 13 May Treatment Harvest Cane/Plot

Soil Sterilants
"Pra itol 5G" 2 cups/stool x x 80 337 27,460
"FPraitol 5G" 2 cups/stool x x 56 377 28,900
"Karmex" 20 lb/100 gal water x x 88 357 27,220
"Karmex" 20 lb/100 gal water x x 196 540 27,140
"Telvar" 20 lb/100 gal water x x 143 486 21,080
"Telvar" 20 lb/100 gal water x x 92 371 29,140
"Hyvar-X" 20 lb/100 gal water x x 303 687 12,300
"Hyvar-X" 20 lb/100 gal water x x 365 342 11,120
"Sinbar" 20 lb/100 gal water x x 115 489 24,220
"Sinbar" 20 lb/100 gal water x x 154 356 17,760
"Monboor-Chlorate" 100 lb/100 gal x x 279 975 11,760
"Chlorbor-D" 100 lb/100 gal water x x 282 679 13,540
"Hibor" 100 lb/100 gal water x x 322 682 12,160

Fcliar Sprays
"Dowpon" 10 lb/100 gal water x x 284 806 14,780
"Dowpon-C" 10 lb/100 gal water x x x 283 961 16,700
"kuron" 10 qt/100 gal diesel oil x x x 345 878 21,480
"Weed-E-Rad + W" MSMA
5 gal/100 gal water on x
plus 5 qt/100 gal water on x x 356 869 21,320
------------------------------------------------------------------------------------------------------------
NB. Plots 4 rows wide x 1/4 mile long, not replicated. Rates in terms of commercial product.


EV71-12
300 copies




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