Note: Descriptions are shown in the official language in which they were submitted.
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LKOXYLATED FATTY ALCOHOLS AS AXILLARY
BUD IN~IIBITORS ON TOBACCO PLANTS
This invention relates to the control of axillary
buds (suckers) in tobacco plants by the application of contact-
5 type chemical sucker control agents. In particular it isdirected to the use of alkoxylated fatty alcohols having 6-10
carbon atoms and a hydrophilic/lipophilic balance (HLB) of
8-14.
Tobacco leaf quality and yield are greatly increased
by "topping" tobacco plants in the mid-bud to late-bud stage of
growth and developmentO This is achieved by removing the
flowers and several adjacent top leaves. As soon as the
inflorescence is removed, many processes become active. One of
these is the accumulation of nicotine and other alkaloids in
the leaves, particularly in ~he upper 2/3 of the plant.
Topping also allows the leaves in the upper part of the plant
` to continue to grow and consequently increase the total yield.
Decapitation (topping) of ~he plant enhances the
growth of a~illary buds or "suckers"; these must be removed
con~inuously or permanently in order to achieve the benefits of
topping. Removal of the suckers may be accomplished by hand,
which is a very time consuming and laborious operation, or by
chemical control.
Two types of chemical agents are available: systemic
and contact. In the United States of America, it is common to
use a combination of both types of sucker control agents. An
application of a contact control agent will be ~ollowed by the
application of a systemic material such as the sorts of maleic
~ydrazide, followed by another possible application of contact
desuckerant. In Canada, owing to the shorter growing season,
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Docket No. 1512
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the systemic control agents have been found to be less suitable
for use resulting in reduced yields, and consequently are not
recommended by agricultural advisers and experts. It is also
more desirable to use contact type desuckerants because of the
lower associated chemical residue in the cured tobacco compared
to the use o~ systemic control agents. Some countries have
adopted a legal limitation on the residue in tobacco.
The most common type of contact suc~er control agent
is composed of approximately 81-87% l-decanol, or a mixture of
l-decanol/l-octanol, plus 19-13% emulsifier of which the most
commonly used is polysorbat~ 80 as disclosed in Canadian Patent
1023164. The commercial products used for comparative purposes
in the examples of this disclosure possessed such a
composition.
Sucker control chemicals are normally applied to the
plant shortly ~efore or after topping. The buds are only
susceptible to chemical control before they start to grow and
elongate. With the commercial fatty alcohol/emulsifier
formulation, any buds that are longer than approximately 2.5 cm
~0 begin to build-up the cuticle layer and become resistant to
chemical damage or l'burn".
From the above, the importance can be seen of
removing all the acti.vely growing suc~ers. In Ontario the
current preferred means of achieving this control is to apply
contact chemical desuckerants formula~ed from fatty alcohols
such as disclosed in the related Canadian Patent 1023164.
An object of one aspect of this invention is to
provide a more economical method for inhibiting the growth of
axillary buds in tobacco plants. Another aspect of this
invention is to provide a method for treating tobacco plants
which can inhibit sucker development with minimal undesirable
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residue d~posits in the leaf tissue. Still another aspect of
this invention, is to provide compositions which may be applied
as convenient aqueous dispersions because they are either
self-e~ulsifying or can be dispersed in water by the addition
of a minor portion of phytobland emulsifier.
In general, benefits of this invention can be
obtained by applying to tobacco plants immediately before or
shortly after topping an alkoxylated saturated C6-C10 alcohol
having an hydrophilic-lipophilic balance of 8-14. The term
hydrophilic-lipophilic balance (HLB) is commonly used to
characterize alkoxylated materials. The value may be
determined empirically by comparison to surfactants of known
HL~ values by emulsifying materials with a known HLB
requirement; alternatively, the HLB value of a surfactant may
be calculated. For ethoxylated compounds, the XLB valuP ~ay be
calculated by dividing the percent ethylene oxide in the
molecule by a factor of 5. The HLB values listed for the
examples in Table l were calculated for ethoxylated alcohols by
the above mentioned method, and determined empirically to a
reasonable proximation ~or propoxylated adducts. Additional
methods for determining HLB are set forth in "The Atlas HLB
System" 4th Printing (1963) ICI Americas Inc., Wilmington,
~elaware USA and in Petrawski, G. E. and Vanotta, J. R., J. Am.
Chem. Soc. pages 284-289 August 1973.
Although various alkoxylated alcohols of the type
disclosed have been found to be effective tobacco sucker
c,ontrol agents, best results, and ones free from undesirable
side effects which could result in detrimental e onomic ~alue
to the tobacco quality or yield, were achieved with a polyoxy-
3n ethylene l-octanol which has an average oxyethylene chain
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length of approximately 3; this compound is thus considered to
be a preferred agent of the type disclosed in this invention.
In general the agents used in the invention are
produced using well known techniques by reacting ethylene or
propylene oxide with saturated alcohols having 6-10 carbon
atoms such as 1, 2 or 3-hexanol, 1, 2, 3 or 4 octanol, 1, 2 or
3 decanol and mixtures and isomers thereof in a pressurized
reactor to produce liquid compounds having ~he general formula
RO(CH2-CH2RlO)nH where R is an alkyl group having 6-10 carbon
a~oms, Rl is H or -CH3, -C2H5 and n is 2-10. The compound may
also contain mixtures of ethylene oxide and propylene oxide
when the alcohol is reacted with mixtures of the oxides or may
be made reacting the alcohols in sequence with the oxides. For
example when 1 mol of l-octanol is reacted with 1 mol of
ethylene oxide and 2 mols of propylene oxide the composition is
written polyoxyethylene (1) polyoxy-propylene (2) -1 octanol,
or poe (1) pop (2) -1 octanol having the formula
C8Hl7o(c2H4o)(c2H3(cH3)o)2H~
The agents of the invention are usually free flowing
liquids which are clear to slightly cloudy. I they are made
in the presenc~ of an alkaline catalyst the liquid may be too
alkaline for use and therefore must be neutralized with acid to
a pH of about 5-7 although in~some instances a slightly higher
or lower pH may not be phytotoxic. The alcohols used to
synthesize the disclosed compositions originate from petroleum
fractions; however, it is contemplated that C6-C10 alcohols
derived from fats and oils would not materiall~ differ in
effectiveness as starting materials for the alkoxylated
products.
In some instances it is preferred to apply the
desuckering 2gents as aqu~ous dispersions employing 5-15% by
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weight of an effective phytobland emulsifier or surface active
agents.
Among the surface active agents found to be useful in
the invention are those classified as anionic, nonionic and
cationic surfactants. Specific anionics surfactants which may
be useful include the sulfated or sulfonated ethers of long and
short chain aliphatic groups such as those having about 15-20
carbon atoms such as the sodium salts of sulfonated alkyl
esters, sulfonated glycol esters and sulfonated alkyl
substituted amides, alkylated aryl sulfonates and dodecyl-
benzene sodium sulfonate), hydroaromatic sulfonates (tetra-
hydronaphthalene sodium sulfonate), and soap such as sodium
laurate, ammonium stearate and diethanol-ammonium oleate.
Useful nonionic surface active agents include monoethers of
polyglycol with long chain fatty alcohol such as the reaction
products of ethylene oxide or polyethylene glycol with long
chain fatty alcohol, monoesters of polyglycols with long chain
fatty acids, including reaction products of ethylene oxide or
polyethylene glycol with lon~ chain fatty acids, partial esters
of polyhydric alcohols with long chain monocarboxylic acids
(glycerol monostearate, sorbitan trioleate) and partial and
complete esters of long chain monocarboxylic fatty acids with
polyglycol ethers or polyhydric alcohols (tristearate acid
ester of polyglycol ether of sorbitan). Cationic surfactants
useful in the invention include quartenary ammonia~salts in
which one of the groups attached to the ni~rogen has an
:~liphatic group h~aving at least 8 carbon atoms (trimethyla~etyl
ammonium halide).
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Method of Preparation for Polyoxyethylene (3) l-octanol:
13.4 kg of l-octanol were loaded into a 36 litre
autoclave 40 g sodium hydroxide was added. Air was removed
under vacuum and replaced with nitrogen gas. Temperature was
raised to 140C and 13.8 kg ethylene oxide added slowly whilst
maintaining a gauge pressure of 206-345 KPa until all the
ethylene oxide had been introduced. The reaction was allowed
to proceed down to 0 KPa gauge pressure. Full vacuum was
pulled at 120C for 15 minutes to remove any unreacted ethylene
lo oxide. The reaction product was removed from the autoclave,
neutralized with with 105 g 85% phosphoric acid, filtered in
the presence of a silacious earth filter aid. The product
analysis is as follows:
Analysis
Hydroxyl Number 209
Acid number 0.1
Water content 0.2%
pH (10%) 7-4
Colour Gardner <1
The following examples are illustrative of aspects of
this invention. Data have been taken from both greenhouse and
field trials. It will be readily apparent from the
compositions which have been found to be effective that
substantially any alcohol having a straight or branched alcohol
chain length within the range C6-C10, or a blend having a
predominance within the said range, will inhibit sucker growth
providing that it is alkoxylated so that it possesses an HLB
value of 8-14. Most alkoxylated alcohols will render the
desired degree of axillary bud growth control, however some are
sufficiently phytotoxic at the level required to make the
compound unsuitable for commercial acceptance and preference.
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The compositions listed in Table 1 serve ~o
demonstrate but not limit the alkoxylated alcohols which can be
used in the practice of the invention.
Table 1
Alkoxylated Alcohols
Composition
Number Av. Com~osition HLB
1 poe (8.0) tri-methyl heptanol13.5
2 poe (5.5) " " 12.0
3 poe (4.0) " 10.5
4 poe (3.3) 9.5
poe (4.0) l-decanol 10.5
6 50% by wt. pop (4.0) tri-methyl
heptanol/50~ #1 9.5
7 pop (1.0) poe (4.0) trimethyl
heptanol ca. 10
8 poe (2.5) tri-methyl heptanol 8.2
8A 80% #8 + 20% polysorbate 80 9.5
9 poe ~2.8) 2-ethyl hexanol 9.7
20 10 poe (2.2~ l-hexanol 9.7
11 poe (2.8) 2-octanol 9.7
12 poe (3.0) l-octanol 10.1
13 50% #2 + 50% #8 9.4
~.B. poe = polyoxyethylene
pop = polyoxypropylene
Unless otherwise stated in the specific examples,
tobacco treatments were conducted using the following
procedures and conditions:
, a) Greenhouse Trials
Plants of tobacco were propagated in flats of
muck in a~heated greenhouse and when of suitable size the
seedlings~were transplanted into 10" diameter plastic pots
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containing a soil/muck mixture in the ratio of 3:1 v/v~ The
plants were selected for uniformity prior to treatment with
sucker control chemicals at the early bud stage. A measured
volume of liquid alkoxylated alcohol, control, or comparative
agent was dispersed in 450 liters of water and applied with a
modified sprayer and boom arrangement similar to that used for
field applications for con~act type sucker control chemicals.
Approximately a 30 ml dose of spray mixture was applied per
plant. Three plants were sprayed per treatment. All
observations were compared against a control solution of poly-
sorbate 80 in water, as well as a registered contact type
sucker control material. Visual observations for leaf phyto-
toxicity were based on a predetermined scale of 0 to 10 with 10
being equivalent to no change. Data was collected for sucker
numbers and weights on a dry weight basis.
b~ Field Trials
A split plot experimental design with four
replications was used. Each plot was comprised of two 24.4
meter rows, 61 cm between plants, 107 cm between rows with only
one row harvested. Plants were topped immediately prior to
application of the materials unless climatic conditions
interfered; under such circumstances spraying commenced at the
earliest opportunity.
Spray materials were applied by commercial high
clearance spray equipment when plants were at the mid-bud stage
for development. All treatments were applied at a spray volume
of 450 liters/heetare (L/ha) at 100 KPa and a ground speed of 6
kpg. The alkoxylated alcohols are applied at dose rates of
.5-6 liters per hectare. Phytotoxicity ratings on a scale of 1
to 10 were taken 10-24 days after spraying, with sucker counts
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being taken a few days later. A representative sample of
suckers from each replica was used to determine dry weights by
freeze drying.
c) Analytical
Reducing sugars were determined by ferricyanide
xeduction. Total alkaloids were determined colorimetrically by
the development of an orange colour in presence of cyanogen
bromide.
Tobacco quality is directly associated with
accumulative effect of a number of chemical, physical and
agronomic parameters. Table 2 below lists the parameters used
to assess ~obacco quality as reported in the illustrative
examples.
Table 2
Tobacco Assessment Parameters
I. Average number of suckers per plant
II. Dry weight of suckers per plant
III. Phytotoxicity rating (0-10)
IV. Weighted average reducing sugars content (%)
20 V. Weighted average total alkaloids content (%)
VI, Weighted average grade index ($ Can. l kg . )
VII. Yield of tobacco (kg.tha.)
VIII. Return Index ($ Can,/ha.)
Example 1
Composition numbers 1, 2 and 3 were applied to Delhi
76 tobacco plants in August at rates of 5.5, 4.4, 3.3, 2~2 and
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1.1 L/ha. Effective sucker control was evident from all three
materials down to the 1.1 L/ha level. At a concentration of
5.5 L/ha. severe burns to leaves and axillary buds was observed
whereas at 2.2 and 1.1 L/ha. only slight damage to leaf tissue
occurred.
Exam~e 2
Composition numbers 3, 4, 5, 6 and 7 as well as
commercial contact type sucker control material A were applied
to Delhi 34 tobacco plants in a greenhouse at Delhi, Ontario in
June. Sucker control efficacy was evaluated after three days
and resuIts tabulated below in Table 3.
Table 3
Composition
Number _ Sucker Control Efficacy
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Rate (L/ha)
Test 0.55 1.1 3.5 5.5 8.0 16.8
3 I 0.0 1.1 4.3 4.8 4.9
4 I 0.6 3.2 4.9 4.8 4.8
I 0.2 0.8 4.2 4.6 4.9
20 6 I 0.1 0.2 1.6 3.2 4.7
7 I 0.7 0.6 2.7 4.3 4.9
Commercial A I - - - - - 4.8
Score: visual assessment of 0-5 uith 5.0 being top score.
-~ Example 3
Composition numbers 3, 4 and 8A, as well as
commercial contact sucker control material A and a Control
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consisting of a solution of polysorbate 80 in 450 liters of
water at a concentration equivalent ~o that contained in 16.8
liters commercial desuckerant A, were applied to Delhi 34
tobacco plants in a greenhouse in Delhi, Ontario in July.
Assessment was made of sucker count, sucker dry weight and leaf
phytotoxicity: the results have been tabula~ed in Table 4.
Table 4
Composition
Number Sucker Control Efficacy
Test Rate (L/ha)
Par. 0.55 1.1 3.5 5.5 8.0 16.8
3 I 4.0 1.0 2.0 2.0 0.3
II 7.7 1.9 0.7 1.3 0.1
III 0 0.7 0.7 1.6 2.1
4 I 3.3 3.0 1.0 0.3 0.3
II 8.7 7.3 2.1 0.5 0.7
III 0.2 0 0.6 1.3 3.5
8A I 7.0 3.7 2.3 0.7
II 7.0 7.4 5.3 1.8 - -
III 0 0.2 0.3 0.2 - -
Commercial A I - - - - - 0.6
II - - - - - 7.1
III - - - _ o
Control I 3.7 3.7 3.0 3.7 3.7 3.7
II 10.6 10.3 10.6 10.7 8.7 8.9
III 0 0 0 0 0 0
Ex mple 4
Composition numbers 9, 10, 11 and 13 as well as
commercial:contact type sucker control material A were applied
to Delhi 76 tobacco plants at the end of July at Delhi
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Ontario. Phytotoxicity ratings were taken on August 18th and
sucker counts two days later. Results have been tabulated in
Table 5.
Table 5
Sucker Control Efficacy
Composition Rate Test Parameters
Number L/ha I II III
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9 6.0 6.6 30 0.62
9.0 4.6 18 1.12
lO10 6.0 7.0 34 0.37
9.0 6.7 39 0.50
11 6.0 7.4 33 0.37
9.0 6.2 31 0.25
13 3.0 5.9 30 2.00
15 Commercial A16.8 0.2 3 0.12
Hand-suckered - 11 48 0
LSD 0.05 - 2.3 20 0.44
Exam~le 5
Composition number 12 and a commercial contact type
sucker control material B were applied to Delhi 76 tobacco
plants at Delhi, Ontario on August 6. Both materials were
applied at a spray volume of 450 liters per ha. at 100 KPa, and
a ground speed of 6 kph, using 3x 8008 nozzles per row for
`~omposition 12, and 2x TG-3 and lx TG-5 nozzle for commercial
25 material B: the latter being the more common nozzle
arrangement used by commercial applicators or growers.
Application was made to two replications of one 24,4 meter row
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per treatment. As no hand suckered control plot was run
concurrently on the same experimental plot, comparison has been
made in Table 7 comparing two commercial fatty alcohol based
sucker control agents with a hand suckered control for tobacco
grown in an adjuvent experiment plot. The crop history for the
trials reported in Tables 6 and 7 have been listed as Tables 8
and 9, respectively.
Table 6
Sucker Control Leaf
lO Composition Rate Efficacy Analysis Agronomics
Number_ _ L/ha I II III IV V VI VII VIII
12 4.5 1.5 3.1 0.50 23.6 2.41 3.~7 2306 8225
Commercial B 16.8 1.6 7.9 0.13 23.7 2.44 3.57 2185 7802
Table 7
Leaf
Composition Rate Sucker Control Analysis Agronomics
Number L/ha I II IV V VI VII VIII
Commercial C 19.62.0 14 25O2 2.27 3.50 2404 8654
Commercial B 16.82.2 15 23.~ 2.28 3.62 2346 8488
~o Hand-Suckered - 15.0 39 23.6 2.33 3.56 2152 7650
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Table 8
CROP HISTORY
Ploughing date April 27
Herbicide April 29, Tillam @ 7.7 L/ha
5 Nematicide May 10, Vorlex @ 45 L/ha (row application)
Cutworm control May 20, Ripcord @ 247 mls/ha
Variety Newdel
Planted May 27
Fertilizer 3-9-18 @ 950 kg/ha plus 252 kg/ha
(sidedressed June 29)
Irrigation July 17-38 mm, July 24-38 mm, August 18-38 mm
Hornworm control August 3, Orthene @ 770 g/ha
Topped August 2
Sprayed August 6 (large suckers removed before
spraying)
Phytotoxicity
ratings August 16
Sucker counts August 2~
Harvests August 13, 19, 28, 31 and September 8
20 Frost date August 29
Ta~le 9
1982 CROP HISTORY
Ploughed April 26
Herbicide April 28, Tillam @ 5.5 kg (active)/300 L/ha
25 Nematicide May 10, Vorlex in row, @ 45 L/ha
Cutworm control PIay 20, Ripcord @ 247 ml/ha
Planted May 29
Variety Delhi 76, seedbed seedlings
Fertilizer 3-9-18 @ 950 kg/ha at planting
3-9-18 @ 250 kg/ha, sidedressed on June 28
Irrigation July 16, 23, and August l9 @ 38 mm each
Horn~orm control Au~us~ 13, Orthene @ 770 g/ha
Topped July 31
5prayed July 30, August 6 and ll
35 Ridomil May 19, 25% WP 4.48 kg/ha (soil)
Harvested August 11, I7, 23, September 2 and 8
Sucker counts August 26
3 tip leaf
measurements August 23
40 Fall Frost August Z9
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One aspect of this invention i8 that alkoxylated
alcohols or their blends having an HLB value higher ~han 9 are
self-emulsifying or soluble in water up to at least 5% v/v
level thus rendering them suitable for use as sucker control
agents without the addition of added inert emulsifier. Table
10 compares the emulsion stability of a selection of such
alkoxylated alcohols in comparison to a commercial contact type
sucker control material. In the majority of cases, ~he
emulsion stability from the alkoxylated alcohol is superior
thereby ensuring more uniform application of the control
material.
Table 10
Emulsion Stability Data
% Separation
15 Composition Water with Time (h)
Number Dilution v/vHardness 0 25 0.5 1.0 2 0
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Commercial A 4% 342 ppm 1.5 2.0 3.0 5.0
12 4% ~ o 0.5 3.0 5.0
1% " 0 0 0.5 0.5
20 11 4% " 0 0 1.0 1.0
4% " 0 0.8 1.8 2.0
9 4% " 2.0 4.0 4.0 5.0
3 4% " 0 0 0 0
A review of the comparative performance of the
alkoxylated alcohols tested suggests that the optimum HLB value
for best sucker control efficacy, dispersion stability and
non-phytotoxicity appears to be approx~mately 10. It can be
seen that the alkyl chain length and s~ereo chemistry of the
parent alcohol has an effect on both the:phytotoxicity ~nd
sucker control functionality of the alkoxylated alcohol. It is
contemplated that closely related alkoxylated adducts of
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l-octanol within the limits of this disclosure would
essentially perform as well as polyoxyethylene (3.0) l-octanol.
The preferred alkoxylating agent would appear to be
ethylene oxide. We could find no advantage to the inclusion of
propylene oxide in the molecule. However, the illustrative
examples shows that compounds within the range of this
disclosure containing propylene oxide do act as sucker control
agents and as such should not be excluded from this invention.
It is contemplated that alkoxylated alcohols containing
butylene oxide may also perform as tobacco sucker control
agents.
Some of the alkoxylated alcohols disclosed in this
invention are available as commercial products, being sold
primarily for their surface active agent properties. Others
are not commonly commercially available. All materials
utilized in the trials reported in this text were synthesized
in a similar manner to the method listed below for composition
12:
Although evaluations were conductèd with Delhi 76 and
34 varieties of tobacco, the invention is not restricted to
those specific varieties. Delhi 76 and 34 are among the three
recommended varieties for Ontario since these varieties
together with Virginia 115 are considered superior to other
varieties of flue-cured tobacco in most respects. Studies have
shown that contac~ type desuckerants are relatively unaffected
by tobacco variety and thus it is contemplated that the
compositions of this invention will inhibit the growth of
axillary buds on other licensed varieties of flue-cured
tobacco.
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