CA1037866A - Fungicidal dispersions - Google Patents

Abstract

FUNGICIDAL DISPERSIONS
Abstract of the Disclosure:
Oily dispersions having an improved systemic fungicidal activity are composed of about 5 to 30 % by weight of BCM, about 60 to 85 % by weight of an aliphatic mineral oil having a flash point of from 65 to 180°C and a viscosity of from 1.5 to 30 centipoise at 20°C, about 6 to 15 % by weight of a combination of dispersible agents comprising a monoalkylphenol polyglycol ether having from 8 to 12 carbon atoms and a tri-isobutylphenol polyglycol ether and about 0.1 to 3 X by weight of calcium (C8 - C15) monoalkylbenzene sulfonate.

Description

~ HOE 73/F 326 The present invention relates to fungicidal disperslons of 2-benzimidazole methylcarbamate (BCM) of the formula ~ N
H
.
It is known from Britiæh Patent Specification No.
1,190,614 that BCM has excellent properties as a systemic plant -fungicide. Because of its complete insolubility in lipoids, however, it does not penetrate easily through the plant sur-- face into the interior of the plant where it can display its -systemic activity. As a consequence, much of the materlal remains on the outer plant surface where it acts as a pro-phylactic fungicide only and is sub~ect to the deteriorating influence of the weather.
The British patent describes a number of ways by which the penetrating capacity of BCM and hence its systemic activity may be improved, such as grinding it to a very fine particle size (below 5 microns) or adding larger-than-usual amounts of so-called "penetrants", i.e. compounds that facilitate the penetration of BCM into the plant interior. However, while these measures remove the drawbacks described above, they create others. For instance, dry milling to a very fine t partlcle slze requires special types of mills and expensive ' 25 filtering apparatus, and the addition of large amounts of i pene*rants may causle toxicity hazards in the treated plants.
Especially, it has not been possible to produce useful dis-per~ions of BCM by the ways descrlbed in the British patent.
29 Such dispersions have a number of advantage over usual

2 ~
,. q~ .
-10378~6 formulations such as dusts and wettable powders.
Since for making dispersions the active compounds are ground in the wet state as slurries they do not require ex-pensive filtering devices. Furthermore, dispersions are more easily dosable and do not dust while handling, thus reducing the hazards of toxicity to humans.
The preparation of stable dispersions is difficult.
In order to prevent premature sedimentation, the active com-pounds have to be ground very finely. In this state, however, strong Van der Waal's attraction forces appear between the dispersed particles causing aggregation and flocculation of the particles. To prevent this a surface active agent is usually added which concentrates at the solid-liquid interface and forms a solvating envelope around the individual particles carrying uniform electric charges and thus preventing agglo-meration. Even so, however, the solvating envelope may break down partially e.g. if the dispersion is kept at higher temper-atures over prolonged periods of time, which results in in-creasing viscosity, flocculation and irreversible sedimen-tation.
It is an object of the present invention to provide stable oily dispersions of BCM.
It is a further ob~ect of the invention to provide oily dispersions of BCM which have an improved systemic fungicidal Z5 activity as compared with previously described BCM-formulations :. :
and which are equallto the most active standard plant fungi-cides such as Benomyl (1-n-butylcarbamoyl-2-methoxy-carbonyl-amino-benzimidazol).
29 The fungicidal oily dispersions of the invention are ;
_ 3 _ ' ~ ,.

r 10;~7~i6 characterized by a content of a) about 5 to 30 % by weight of a compound of the formula ~ H-COOC~3 b) about 60 to 85 % by weight of an aliphatic mineral oil having - - -a flash point off`from 65 to 180C and a viscosity of from 1.5 to 30 centipoise at 20, c) about 6 to 15 % by weight of a combination of dispersible agents comprising a monoalkylphenol polyglycol ether having from 8 to 12 carbon atoms and a triisobutylphenol polyglycol ether and d) about 0.1 to 3 % by weight of calcium (C8 -~C15) monalkyl-benzene sulfonate.
Suitable mineral oils are~ for example, aliphatic and/or alicyclic hydrocarbons or mixtures thereof, especially technical grade mineral oils consisting essentially of straight-chain ali-phatic or of alicyclic hydrocarbons. Such mineral oils are, for `
instance Essobayol(R)~ e.g. Essobayol 50, Essobayol 80 and Essobayol 90, Shellsol K(R), BP-n-Paraffine I and BP-n-Paraffine III. These mineral oils have viscosities between 1.5 and 29.5 centipoise, flash points between 66 and 178C, boiling ranges between 192 and about 420C and paraffine contents above 95 %
until 100 %. -Suitable monoalkylphenol polyglycol ethers are especially those having 8 to 9 carbon atoms in the alkyl moiety and variable degrees of ethoxylation, preferably 8 to 12 ethylene -- 4 - ~

HOE 73~F ~26 , 1037~6 oxide (AeO) units. Examples of such compounds are the types commercially available under the trade name "Triton(R)", for example Triton X-45, X-114 and X-207. Their proportion in the total formulation is advantageously from 5 to 10 % by weight .
The triisobutylphenol polyglycol ethers which are also re-quired are commercially available under the trade name "Sapogenat(R)", for example Sapogenat T 100, T 110 or T 150, where the polyglycol portion has a degree of polymerization of from 8 to 15, preferably of from 10 to 11. These compounds are preferably used in amounts of 1 to 5 % by weight.
Calcium salts of the higher monoalkylbenzene sulfonate5 are used as additives to the dispersions owing to their oil-solubility. Especially preferred are calcium salts of (C10-C12) monoalkylbenzene sulfonic acids, particularly of dodecylbenzene sulfonic acid, The Ca-alkylbenzene sulfonates may be added as solids or, preferably, in alcoholic solution, for example in isopropanol or isobutanol.
- The oily dispersions of the invention are prepared inknown manner, for example by grinding the starting material in ball mills by means of quartz pearls having a diameter of from 1 to 2 mm. The active ingredient in the dispersions obtained has a particle size of less than 10, preferably of less than 5 micrOnh.
The compsition of the emulsifier is critical for the properties of the folrmulation. Comparative tests have shown that commonly used emulsifiers such as polyglycol esters of l oleic acid, stearic acid or palmitic acid, polyglycol deri-¦ 29 vatives of dodecylmercaptan, of oleylamine~ or stearylamines ; - 5 -HOE 73~F ~26 do not form storable dispersions with BCM. The same applies to polyglycol ethers of oleyl, stearyl and technical coconut fat alcohols and of dodecylalcohol, of varying degrees of poly-merization. Tests with emulsifiers of the type of polyoxethylene sorbitan having varying degrees of polymerization gave also unsatisfactury results. Alkylphenol polyglycol ethers used alone were likewise unsuitable.
The dispersions according to the invention on the other hand are distinguished by an excellent activity and a high storability. In this respect they are considerably æuperior to the dispersions known from British Patent Specification No. 1,190,614 (example 5). Their efficiency is also superior to known wettable powder formulations of BCM and to Benomyl formulations, as the following examples illustrate.
E X_A M P L E 1 (Comparative agent 1) According to example 5 of British Patent Specification No. 1,190,614 a dispersion was prepared containing 26 ~ by weight of BCM

A~ 38.57 % by weight of indene resin (Piccolyte resin S-10) - 26.43 % by weight of low boiling isoparaffin oil (Soltrol 130(R)) 9 % by weight of lauryl alcohol polyglycol ether.
115.71 g (38.57 %) of Piccolyte resin S-10 were dissolved in 79.29 g(26.43 %) of Soltrol 130 and introduced into the stirring compartment of a ball mill. Then 78 g (26 %) of BCM, 27 g (9 %) of laurylalcohol polyglycol ether having a poly-29 merization degree of 10 and 500 g of 1 mm quartz pearls were .. , - . , . . ~ . , . .................................... -- ' ` ' .' ~ '' ' ,. , ,-~037866 ¦ added and the whole was ground for 6 hours. Thereafter the ¦ BCM had a particle size of less than 5 microns. The quartz pearls were then separated by sieving.
After a storage life of 3 months the dispersion wa~
viscous, the sediment could not be redispersed in the container and dispersed in water only with great difficulty.

., A BCM dispersion according to the invention and containing 25 % by weight of BCM
~ 101 % by weight of Ca-dodecylbenzene sulfonate :, (in the form of a 70 % solution in i-butanol) 2 % by weight of triisobutylphenol polyglycol ether ("Sapogenat T-100(R)") 156 % by weight of octylphenol polyglycol ether ~ ("Triton X-207(R)) i! 66 % by weight of paraffinic mineral oil i ("Essobayol go(R) ~ ) was prepared in the same manner.
Essobayol 90 has the following characteristics:
i ~iscosity 27.5 cp at 20C
flash point 170C
boiling range 300 - 400C
parafflne cont~t 95 Another BCM dispersion had the following composition:
20.00 % by ~eight of BCM ;
2.25 % by weight of Ca-dodecylbenzene sulfonate (in the form of a 70 % solution in i~obutanol)

3.80 % by weight of triisobutylphenol polyglycol ether ! ~ 7 ~
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10378~6 ("Sapogenat T-100(R)") 8.75 % by weight of octylphenol polyglycol ether t"Triton X-207(R)") 65.20 % by weight of paraffinic mineral oil ("Essobayol go~R) ll ) Commercial wettable powder based on Benomyl was used as a further comparatif agent (comparatif agent 2) In order to demonstrate the biological efficiency the following tests were carried out, which were also confirmed by field tests.
E X A M P L E 4:
Cucumber plants were cut off above the first two true leaves. As soon as these were completely grown, the cotelydons situated below were also removed and th lower parts of the leaves were sprayed to the drip off with aqueous preparations of the compo8itions of examples 2 and 3 by means of a micro-applicator. Contamination by active ingredient of the upper surface of the leaves and other parts of the plant as well as the 80il was thus prevented.
The comparative preparation was a compo~ition prepared according to British Specification No. 1,190,614 (comparative agent 1) and a commercial wettable powder based on Benomyl (comparative agent 2).
e composition of the test preparations and of the com-parative agent~ were applied in concentrations of 1000, 500, 250, 125, 60 and ~0 mg each of active ingredient per liter ~ of 8praying liquid.
3 After drying, the upper surface of the leaves wa8 infected 29 with conidia of cucumber mildew (Erysiphe cichoracearum).

~ . .

HOE 73/F ~26 1a378~i6 The plants were then placed in a green house at a relative humidity of 80 to 90 ~0 and a temperature of from 23 to 25C.
After an incubation time of 14 days the plants were examined visually as to the degree of damage by cucumber mildew.
The degree of damage was expressed in percent of attacked sur-face of the leaves compared to infected untreated controls.
From the result indicated in table 1 it is seen that the activity of the dispersion prepared according to British Patent Specification No. 1,190,614 was considerably lower than that of the oily dispersions prepared according to examples 2 and 3 of the invention. The latter dispersion was also by far superior to the commercial formulation of Benomyl.
E X A M P L E 5:
Apple seedlings in the 8-leaf-state were defoliated, es~ept for the 4 yougest unfilded leaves, strongly infected with conidia of apple scab (Venturia inaequalis) and placed dripping wet in a climatic chamber having a relative humidity of 100 % and a temperature of 20C.
After 2 days the plants were put in a green-house ad-usted to a temperature of 18C and a relative humidity of 90 to 95 %.
After 3 days the lower surfaces of the leaves were sprayed to the drip off with aqueous reparations of the oily dispersions prepared according to examples 2, 3 and 4 using the same pre-cautions as in Example 3.
A dispersion prlepared according to British Patent Speci-fication No. 1,190,614 and a usual wettable powder formulation of Benomyl (comparative agent 2) were applied as comparative 29 a~ents in an analogous manner. The applied concentrations were _ g _ ;:

HO~ 7 ~F_~26 .
10378~i6 1000, 500, 250, 60 and 30 mg each of active ingredient per liter of spraying liquid.
After drying the plants were replaced in the green-house and examined visually as to the degree of damage by apple scap after an incubation time of 21 days. The degree of damage was expressed in percent of attacked surface of the leaves calcu-lated on infected untreated the controls.
From the test result indicated in table 2 it is seen that the activity of the formulations according to the invention was - 10 considerably higher than that of the composition prepared according to British Patent Specification No. 1,190,614.
The formulations according to the invention were also superior to the composition based on Benomyl.

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Claims (3)

What is claimed is:

1. Fungicidal dispersions, comprising a) about 5 to 30 % by weight of the compound of the formula b) about 60 to 85 % by weight of an aliphatic mineral oil having a flash point of from 65 to 180°C and a viscosity of from 1.5 to 30 centipoise at 20°

c) about 6 to 15 % by weight of a combination of dis-persible agents comprising a monoalkylphenol polyglycol ether having from 8 to 12 carbon atoms and a triiso-butylphenol polyglycol ether and d) about 0.1 to 3 % by weight of calcium (C8-C15) mono-alkylbenzene sulfonate.

2. Fungicidal dispersions as claimed in claim 1, wherein the mineral oil is Shellsol(R)K .

3. Fungicidal dispersions as claimed in claim 1, wherein the mineral oil is Essobayol(R)90.