Plant growth regulation using 3-cyano-1-phenylpyrazoles such as fipronil

This invention relates to a new method of plant growth regulation whereby a 1-phenylpyrazole such as fipronil is applied to a crop or a seed.

The present invention relates to a new method for treatment of plants to 
induce growth regulating responses. 
The term "method for regulating plant growth" or the term "growth 
regulation process" or the use of the words "growth regulation" or other 
terms using the word "regulate" as used in the instant specification 
relate to a variety of plant responses which attempt to improve some 
characteristic of the plant as distinguished from pesticidal action, the 
intention of which is to destroy or stunt the growth of a plant or a 
living being. For this reason the compounds used in the practice of this 
invention are used in amounts which are non-phytotoxic with respect to the 
plant being treated. Plant growth regulation is a desirable way to improve 
plants and cropping so as to obtain better plants and better conditions of 
agriculture practice. 
The present invention provides a method for regulating the growth of plants 
comprising applying to said plants, to the seeds from which they grow or 
to the locus in which they grow, a non-phytotoxic, effective plant growth 
regulating amount of a compound having the formula: 
##STR1## 
wherein: R.sub.1 is CN or methyl; 
R.sub.2 is S(O).sub.n R.sub.3 ; 
R.sub.3 is alkyl or haloalkyl; 
R.sub.4 is selected from the group comprising a hydrogen atom, a halogen 
atom, and a radical which may be --NR.sub.5 R.sub.6, C(O)OR.sub.7, 
--S(O).sub.m R.sub.7, alkyl, haloalkyl, --OR.sub.8, or 
--N.dbd.C(R.sub.9)(R.sub.10); R.sub.4 is preferably a amino group, which 
is unsubstituted or which bears one or two substituents selected from the 
group consisting of alkyl, haloalkyl, acyl and alkoxycarbonyl; 
R.sub.5 and R.sub.6 are independently selected from a hydrogen atom, alkyl, 
haloalkyl, --C(O)alkyl, --S(O).sub.r CF.sub.3 ; or R.sub.5 and R.sub.6 
form together a divalent radical which may be interrupted by one or more 
heteroatoms; 
R.sub.7 is selected from alkyl or haloalkyl; 
R.sub.8 is selected from alkyl, haloalkyl or the hydrogen atom; 
R.sub.9 is selected from the hydrogen atom and alkyl; 
R.sub.10 selected from phenyl or heteroaryl that is optionally substituted 
by one or more hydroxy, a halogen atom, --O-alkyl, --S-alkyl, cyano, or 
alkyl or combinations thereof; 
X is selected from the Nitrogen atom and the radical C-R.sub.12 ; 
R.sub.11 and R.sub.12 are independently selected from a halogen atom or the 
hydrogen atom; 
R.sub.13 is selected from a halogen atom, haloalkyl, haloalkoxy, 
--S(O).sub.q CF.sub.3, --SF.sub.5, preferably from a halogen atom, 
haloalkyl, haloalkoxy, --SF.sub.5 ; 
m,n,q,r are independently selected from 0, 1, and 2; 
provided that when R.sub.1 is methyl, R.sub.3 is haloalkyl, R.sub.4 is 
NH.sub.2, R.sub.11 is Cl, R.sub.13 is CF.sub.3, and X is N. 
The alkyl and alkoxy groups of the formula (I) are preferably lower alkyl 
and alkoxy groups, that is, radicals having one to four carbon atoms. The 
haloalkyl and haloalkoxy groups likewise preferably have one to four 
carbon atoms. The haloalkyl and haloalkoxy groups can bear one or more 
halogen atoms; preferred groups of this type include --CF.sub.3 and 
--OCF.sub.3. 
A preferred group of plant growth regulating 1-phenylpyrazoles for use in 
the present invention are those of formula (I) wherein: 
R.sub.1 is CN; and/or 
R.sub.4 is --NR.sub.5 R.sub.6 ; and/or 
R.sub.5 and R.sub.6 are independently selected from the hydrogen atom, 
alkyl, haloalkyl, --C(O)alkyl, C(O)OR.sub.7 ; and/or 
X is C-R.sub.12 ; and/or 
R.sub.13 is selected from a halogen atom, haloalkyl, haloalkoxy, or 
--SF.sub.5. 
A particularly preferred group of plant growth regulating 1-phenylpyrazoles 
for use in the present invention are those of formula (I) wherein: 
R.sub.1 is CN; 
R.sub.4 is --NR.sub.5 R.sub.6 ; 
R.sub.5 and R.sub.6 are independently selected from the hydrogen atom, 
alkyl, haloalkyl, --C(O)alkyl, C(O)OR.sub.7 ; 
X is C-R.sub.12 ; 
R.sub.13 is selected from a halogen atom, haloalkyl, haloalkoxy, or 
--SF.sub.5. 
Specific pyrazole derivatives usable in the method for regulating plant 
growth falling within the scope of the present invention include 
5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoromethyl 
sulfinylpyrazole. This especially preferred plant growth regulator for use 
in the present invention is hereafter called compound A. 
According another feature of the instant invention, there is provided a 
method of regulating the growth of a plant at a locus at which there are 
no insects, or at which they are not expected to be or through which they 
are not expected to pass, or traverse, or inhabit or visit or fly, said 
method comprising the application thereto or to the plant seed therefrom 
of a non-phytotoxic, effective plant growth regulating amount of a 
compound of formula (I). 
Another aspect of the invention is method for regulating the growth of 
plants selected from the group consisting of rice, corn, cereal, vegetable 
and soybean plants and turf, said method comprising applying to said 
plants, to the seeds from which they grow or to the locus in which they 
grow, a non-phytotoxic, effective plant growth regulating amount of a 
compound of formula (I). 
Another aspect of the invention is a method for regulating the growth of 
soybean plants comprising applying to the seeds from which said soybean 
plants grow, prior to sowing said seeds, a non-phytotoxic, effective plant 
growth regulating amount of a compound of formula (I). 
Another aspect of the invention is a method for treating plants in need of 
growth regulation, comprising applying to said plants, to the seeds from 
which they grow or to the locus in which they grow, a non-phytotoxic, 
effective plant growth regulating amount of a compound having the formula 
(I). This need of growth regulation is particularly great when the plants 
or seeds therefrom are weak or feeble or stressed or are not in growing 
conditions favorable to the growth of plants. 
The preparation of compounds of formula (I) can be effected according to 
any process described in International Patent Publications No. WO 
87/03781, WO 93/06089 and WO 94/21606, as well as in European Patent 
Publication numbers 0295117, 0403300, 0385809, and 0679650, German Patent 
Publication 19511269 and U.S. Pat. Nos. 5,232,940 and 5,236,938. 
The 1-phenylpyrazoles of formula (I) used in the method of the present 
invention fall within a broader group of compounds which has been 
previously described as insecticides. It has been found that, 
surprisingly, the compounds of formula (I) and most especially compound 
(A), display a wide variety of plant growth regulating properties, 
depending upon the concentration used, the formulation employed and the 
type of plant species treated. 
By virtue of the practice of the present invention a wide variety of plant 
growth responses, including the following, may be induced: 
a. more developed root system 
b. tillering increase 
c. increase in plant height 
d. bigger leaf blade 
e. less dead basal leaves 
f. stronger tillers 
g. greener leaf color 
h. less fertilizers needed 
i. less seeds needed 
j. more productive tillers 
k. less third non productive tillers 
l. earlier flowering 
m. early grain maturity 
n. less plant verse (lodging) 
o. longer panicles 
p. increased shooth growth 
q. improved plant vigour 
r. early germination 
s. more fruit and better yield (weight) of fruit. 
It is intended that as used in the instant specification the term "method 
for regulating plant growth" or "method for regulating the growth of 
plants" means the achievement of any of the aforementioned nineteen 
categories of response or any other modification of plant, seed, fruit or 
vegetable (whether the fruit or vegetable is unharvested or harvested) so 
long as the net result is to increase growth or benefit any property of 
the plant, seed, fruit or vegetable as distinguished from any pesticidal 
action (unless the present invention is practised in conjunction with or 
in the presence of a pesticide, for example a herbicide). The term "fruit" 
as used in the instant specification is to be understood as meaning 
anything of economic value that is produced by the plant. 
Suitable formulations for plant growth regulating compositions are known. A 
description of suitable formulations which may be used in the method of 
the invention can be found in international patent publications WO 
87/3781, 93/6089, 94/21606 as well as in European patent application 
295117 and U.S. Pat. No. 5232940. The formulations described in said prior 
art are mainly intended for insecticidal purposes. Formulations or 
compositions for plant growth regulating uses can be made in a similar 
way, adapting the ingredients, if necessary, to make them more suitable to 
the plant or soil to which the application is to be made. 
The 1-phenylpyrazoles of formula (I) may be applied for plant growth 
regulating purposes to the foliage of plants and/or to the soil in which 
said plants are growing. Applications to the soil are often in the form of 
granules which are usually applied in sufficient amount to provide a rate 
of from about 0.005 kg/ha to about 0.5 kg/ha of active ingredient, 
preferably between 0.01 and 0.2 kg/ha. 
A preferred embodiment of the invention is a method for regulating the 
growth of plants comprising applying to the seeds from which said plants 
grow, prior to sowing said seeds, a non-phytotoxic, effective plant growth 
regulating amount of a compound having the formula (I). The seed may be 
treated, especially by coating or embedding or impregnation or soaking or 
dipping in liquid or paste formulations which are known per se and are 
subsequently dried. Seed comprising 2 to 1000 gram per quintal of a 
compound of formula (I), preferably 5 to 800 g/q, most preferably 5 to 250 
g/q are particularly appropriate for this purpose. 
Advantageously, compounds of formula (I) can also be formulated as flowable 
compositions, wettable powders, microemulsions and the like, all of which 
lend themselves to soil, water and/or foliage application and provide the 
requisite plant growth regulating action. Such formulations include the 
compounds of the invention admixed with inert, agriculturally acceptable 
solid or liquid diluents. 
The formulations may comprise other active ingredients in addition to the 
compound of formula (I). For example, mixtures with fungicidally active 
ingredient may be used. 
Wettable powders and granular concentrate formulations for use in the 
method of the invention can be prepared by grinding together a 
1-phenylpyrazole compound of formula (I), with about 1% to 20% by weight 
of a solid anionic surfactant. One suitable anionic surfactant is a 
dioctyl ester of sodium sulfosuccinic acid. About 85% to 95%, by weight, 
of an inert solid diluent, such as montmorillonite, attapulgite, chalk, 
talc, kaolin, diatomaceous earth, limestone, silicates or the like is also 
included in such formulations, as well as other adjuvants as previously 
indicated. 
In addition to the granules and wettable powder formulations described 
hereinabove, flowable formulations can be used since they are readily 
dispersible in water and can be applied to the proper locus where the 
plant growth regulating action is required. 
The pyrazole derivatives used in the method of the present invention have a 
low solubility in water but can be used at low doses. So, they can be 
applied to plants in aqueous solutions or emulsions or, preferably, 
suspensions comprising water and, optionnally, other adjuvants. Partial 
aqueous media include those formed of water and, for instance, acetone or 
methyl ethyl ketone. Any liquid medium can be used provided that it is not 
toxic to the plant, and preferably not to the environment. Where any 
particular pyrazole derivative is less water-soluble, it can be 
solubilized by the use of co-solvents or wetting agents or it can be 
suspended by mean of dispersing agents which can be used simultaneously 
with e.g. surfactants and extenders. Other media, including solids, like 
talc, will occur to those skilled in the art. The compounds used in the 
process of this invention can be absorbed onto solid carriers such as 
vermiculite, attaclay, talc and the like for application via a granular 
vehicle. Application of diluted aqueous formulations or solids is 
accomplished using conventional equipment that is well known in the art. 
As will be demonstrated in connection with certain examples in this 
specification, compounds used in the process of the present invention have 
been effective in regulating plant growth and development in connection 
with a wide variety of plant species at various concentrations of active 
pyrazole compounds. 
The precise amount of pyrazole compound to be used will depend, inter alia, 
upon the particular plant species being treated. A suitable dose may be 
determined by the man skilled in the art by routine experimentation. The 
plant response will depend upon the total amount of compound used, as well 
as the particular plant species which is being treated. Of course, the 
amount of pyrazole compound should be non-phytotoxic with respect to the 
plant being treated. 
Although the preferred method of application of the compounds used in the 
process of this invention is directly to the foliage and stems of plants, 
the compounds can be applied to the soil in which the plants are growing. 
Such compounds will be root-absorbed to a sufficient extent so as to 
result in plant responses in accordance with the teachings of this 
invention. 
The process of the present invention is often preferably carried out on 
growing plants as set forth in many of the examples in this specification. 
However, the process of the present inventions is advantageously carried 
out as a seed treatment, for instance, of rice seed, lettuce seeds, oat 
seeds and soybean seeds.

The following examples are illustrative of methods of plant growth 
regulation according to the invention, but should not be understood as 
limiting the invention as modifications in materials and methods will be 
apparent to the skilled worker. All measurements of plant growth 
regulating effects were determined using untreated seeds and/or plants as 
controls. 
EXAMPLE 1 
Rice seed was treated by mixing the seed with a suspension concentrate 
containing 5% w/w of compound A. This mixing resulted in a coated seed 
which was immediately sown on a 1000 m2 area so as to have 30g/ha of 
active ingredient. The results were observed from the seedling emergence 
through to harvest. Some insects were present and killed. Results were 
observed 35 days after sowing. A 5.4% yield increase was observed with 
following plant growth regulating effect: greener plants, higher plants, 
less dead basal leaves, bigger leaf blade, flowering 2 days earlier. 
EXAMPLE 2 
Example 1 was repeated. Results were observed 60 days after sowing. A 7% 
yield increase was observed with following plant growth regulating effect: 
greener plants, higher plants, less dead basal leaves, bigger leaf blade, 
flowering 2 days earlier, longer panicles, brighter color of grain. 
EXAMPLE 3 
Example 1 was repeated except that 40 g/ha of active ingredient were 
applied. The same results were obtained but also stronger tillers were 
observed as well as less plant verse. 
EXAMPLE 4 
Example 1 was repeated except that 50 g/ha of active ingredient were 
applied. The same results were obtained but also a 15% growth tillers 
increase was observed as well as a 9.5% yield increase. 
EXAMPLE 5 
Rice seed was sown and the seed bed (acid sulphate soil) was treated (soil 
treatment) by spraying it with a suspension concentrate containing 5% w/w 
of compound A. After treatment, transplantation of rice was made as usual. 
The treatment of seed bed was made 24 days before transplantation. The 
following plant growth regulating effects were observed: stronger 
seedlings, flowering 6 days earlier, 25% increase in tillers, harvest 6 
days earlier, 100% yield increase. 
EXAMPLE 6 
Rice seed was sown and the flooded seed bed was treated (soil treatment) by 
sprinkling granules containing 0.3% w/w of compound A on it. After 
treatment, transplantation of rice was made as usual. The treatment of 
seed bed was made 11 days before transplantation. The following plant 
growth regulating effects were observed: stronger seedlings, 50% increase 
in tillers, fertilizers reduced by 40 kg urea and 50 kg/ha of 
superphosphate, 7% yield increase. 
EXAMPLE 7 
Corn seeds were sown in 3.5 liters pots (six plants per pot). Immediately 
after sowing, granules containing compound A were spread on the soil. The 
granules contained 1.5% w/w of active ingredient and they were spread so 
as to have a dose of 120 g/ha of active ingredient on the soil. Plants 
were properly watered. One month and one week after, the dry root weight 
was measured. The root weight is about 42 g for the treated pots and 30 g 
for the untreated pots. 
EXAMPLE 8 
Rice seed was germinated 48 hours in water at 30.degree. C. and then sown 
in pots. After the emergence of the seedings, granules containing 0.3% w/w 
of compound A were applied to the soil at rates of 200 and 100 g/ha. No 
phytotoxicity was observed with any of the formulations or rates. 
Periodically, sets of pots were harvested and dry weights of the roots 
were determined. Pyrazole treatments increased the dry root mass per pot 
by an average of 36% over that of the untreated seedlings 28 days after 
treatment. 
EXAMPLE 9 
Soybean seed was treated with a mixture of an insecticidally active 
compound together with a fungicidally active compound. Soybean was sown at 
60 kg/ha in a plot having, after growing, 1000 plants per plot. The seeds 
germinated and the plants were grown up, up to the time of harvest, and 
observations were made all along that time. 
The results in the following Table demonstrate dearly that the plant growth 
regulating activity of compound A is not attributable simply to its 
insecticidal activity. Other comparable insecticides do not produce plant 
growth regulation whereas the results obtained with compound A clearly 
show a plant growth regulatory effect. 
The following active ingredients and doses were applied: 
______________________________________ 
Yield Number 
Dose of Dose of 
(kg) of pod 
insecticide 
fungicide 
per 250 
per plants 
Insecticide 
Fungicide 
in g/ha in g/ha 
plants 
(average) 
______________________________________ 
Compound A 
Benomyl 30 150 4.87 26 
Compound A 
Captan 30 300 6.21 26.7 
Carbosulfan 
Benomyl 300 150 3.46 19.6 
Carbosulfan 
Captan 300 300 2.18 16.8 
Thiodicarb 
Benomyl 675 150 3.27 16.5 
Thiodicarb 
Captan 675 300 2.15 21.1 
Methomyl Benomyl 225 150 1.85 16.2 
Methomyl Captan 225 300 3.57 22.7 
______________________________________ 
The following observations were made: Bean fly control was higher than 95% 
both with compound A and Carbosulfan. The plant growth with compound A was 
very much accelerated during the first month after sowing. Compound 
A-treated plants were taller and healthier, leaves were wider, greener and 
shiny, branches were stronger and there were more branches, and plant 
canopying was faster than other treatments so that there were less weeds. 
The number of pod/plant was 24 to 37% higher with Compound A than with 
Carbosulfan. The yield was much higher when compound A was applied. Both 
the yield and the average number of pods per plant were also higher using 
compound A than when thiodicarb and methomyl were used. 
EXAMPLE 10 
Rice seed was treated with a formulation of compound A at a rate of 40 
g/hectare field-sown at a rate of 150 kg/hectare and covered with a thin 
layer of soil. Afterwards the seed was allowed to germinate and the plants 
grow to maturity and the rice crop harvested. A yield increase of 660 
kg/hectare above normal conditions (not sown seed treated with compound A) 
was found. The amount of savings in fertiliser was the following: 
Nitrogen--18 kg/hectare that is to say 18% less than standard protocol; 
Phosphates 7 kg/hectare, that is to say 16% less than standard protocol. 
When repeating the experimental conditions of examples 1 to 10 with loci in 
which no insects were expected to be or to pass through, inhabit, visit or 
fly through, the same results were obtained: the plant growth regulation 
effects of compound A were the same as the conditions in which insects 
were present at the loci. The insects, if any, were eliminated by 
application of compound A. When no insects were expected, there is no 
reason to apply compound A as an insecticidally active ingredient or 
composition. The application of compound A for plant growth regulation 
purposes was producing the effects as indicated in examples 1 to 10. 
While the invention has been described in terms of various preferred 
embodiments, the skilled artisan will appreciate that various 
modifications, substitutions, omissions and changes can be made without 
departing from the spirit thereof. Accordingly, it is intended that the 
scope of the present invention be limited solely by the scope of the 
following claims, including equivalents thereof.