CS228908B2 - Acaricide - Google Patents

Description

BACKGROUND OF THE INVENTION The present invention relates to acaricidal compositions effective against hibernating ova, containing as active ingredient a hydroquinone diether group. The invention further relates to a method of controlling mites on useful plants, in particular to a method of controlling such pests, comprising treating the hibernating eggs of the mites or the compositions containing said compounds.

In evaluating the acaricidal activity of compounds active against mites, a distinction should be made between ovicidal activity against summer eggs and ovicidal activity against hibernating eggs.

Some mite species hibernate at the egg stage, and these hibernating eggs are less sensitive to pesticides compared to summer eggs, due to both the resting stage of embryonic life and the existence of a barrier created by the chorion of the hibernating egg, which is more resistant penetration of the active substance.

Various acaricidally active compounds are known, some of which are active against mite summer eggs, others are active against mite adults. However, due to the special properties of the hibernating ova, most of the known acaricidal compounds have proven ineffective on this type of ova.

Other compounds have only been shown to be partially active, and this exclusively during a short period of time around the hatching of the eggs. Winter mite control is generally carried out using phosphoric acid esters (especially parathion) in mineral oils. Again, the efficacy of such compositions is always incomplete and the desired results are only achieved when applied during the hatching period.

Weather conditions are often unfavorable in a short period of time in which this treatment can be effective. Treatment prior to the aforementioned period of time is poorly effective on winter eggs, since, as mentioned above, they are particularly resistant to pesticide penetration. In contrast, delayed treatment may result in phytotoxicity, as plants at this vegetative stage are sensitive to numerous mineral oils.

The existence of specific products effective against hibernating eggs would make it possible to carry out treatments in the winter and thus eliminate the above-mentioned difficulties, while also benefiting from the fact that many insects that act as natural enemies of mites and these mites kill. From a practical point of view, the possibility of protecting cultures against mite infestations in winter, ie at a time when there is not so much work in agricultural plants, is undoubtedly another advantage.

As far as is known, there are no specific acaricidal compounds on the market which are effective against hibernating ova.

European Patent Publication No. 37,092 describes dihydroethers of hydroquinone, which can be summarized by the general formula I

R-O- <O> -O- < ^c H ₂ ) _m -X- (CH ₂ ) _n -r (1) in which

R represents an alkyl or alkenyl group having 4 to 18 carbon atoms,

X represents an oxygen atom, a group —CH = CH- or -С = C—, each of the symbols man, which may be the same or different, represents an integer positive number of 1 to 4, and

Y is OH, SH, -O-R ¹ , -S-R ^1, or -O-C-R ² , wherein

II o

R ¹ represents an alkyl group having 1-4 carbon atoms, alkenyl or alkinyl with 2 to 4 carbon atoms and

R ² represents an alkyl group having 1 to 4 carbon atoms, cycloalkyl having 3 to 6 carbon atoms or phenyl.

The compounds of the formula I described in the above-mentioned published European patent application exhibit acaricidal activity against both spider mites and their summer eggs.

In addition, the above compounds have practically negligible toxicity to warm-blooded animals and fish and are not phytotoxic, even at very high doses, for the most widely used agricultural crop plants.

It has now been found that some of the compounds of formula (I) above exhibit particularly high acaricidal activity against mite hibernating eggs. These compounds can be described by the following formula (II) in which:

R * represents an alkyl group having 8 to 11 carbon atoms and

R "is hydrogen, alkyl having 1 to 4 carbon atoms, allyl or a radical of formula -C-R ² wherein

O

R ² represents an alkyl group having 1 to 4 carbon atoms, cycloalkyl having 3 to 6 carbon atoms or phenyl.

SUMMARY OF THE INVENTION The present invention relates to acaricidal compositions which are active against mite hibernating eggs, characterized in that they contain one or more compounds of the formula II as active ingredient.

The invention also relates to a method for combating mites on crops by applying to the hibernating eggs of the mites, either as such or in the form of suitable compositions.

For practical use in agriculture, the activity of the compounds of formula (II) against overwintering mites is more than satisfactory. The compounds of formula (II) show high acaricidal activity against hibernating ova, even when applied at relatively low doses.

In addition, the above compounds, when properly applied to affect all mites, have virtually total acaricidal activity and, as a result, the plants remain uninfected for a long time (even up to two months after the hatching period of the eggs), allowing considerable delay in treatment against adult mites, which may occur on the plant later as a result of a new infection of a different origin.

In addition to the above mentioned application disadvantages, the known compositions used against winter fowl eggs (e.g. mineral oils containing phosphoric acid esters) do not show total efficacy and at least two additional spring treatments with these acaricidal agents must be carried out to achieve the same results.

For practical agricultural applications, the compounds of formula (II) are preferably used in the form of suitable compositions, with the particular aim of achieving the best possible distribution of the active ingredient in such a way as to affect all mite eggs often found in such places of plants. where they are hard to hit.

The aforementioned compositions may contain, in addition to one or more compounds of formula (II) as active ingredient, an inert carrier and a surfactant.

The choice of carrier and other ingredients will depend upon the type of formulation desired.

Suitable formulations are emulsifiable

RO - (O - O - (CH ₂ ) ₃ -C ^C - CH, or (II) concentrates consisting of the active ingredient, a liquid carrier such as an organic solvent, and a surfactant, As examples of organic solvents useful in the above aromatic or alkylaromatic hydrocarbons such as industrial xylene or other commercial mixtures of alkylaromatic hydrocarbons, alcohols such as butyl or isoamyl alcohol, ketones such as ethyl amyl ketone or cyclohexanone.

Examples of surfactants which can be used in the above compositions are alkylbenzene sulfonates, polyoxyethylated alkylphenols, polyoxyethylated vegetable oils, polyoxyethylated fatty acid glycerides, polyoxyethylated sorbitan oleate, or mixtures thereof.

In the above compositions, the individual components may be present in the following amounts:

A - active substance (compound of formula II)

0.5 - 50% by weight B - organic solvent - 80% by weight C - surfactant

0.5 - 20% by weight

It is known that mineral oils show some activity against hibernating ova. This efficiency, which is not very pronounced, is essentially of a physical nature. These oils can cover the mites' eggs with a very thin film, which prevents the exchange of gases and often causes the death of the embryo.

It is therefore also possible to add to the compositions described above also mineral oils which act both as carrier and as active ingredient.

Mineral oils suitable for this purpose are commercial oils having a non-sulphonable content of 80% or more. In this case, the substances mentioned above can be used as solvents and surfactants.

In these compositions, the individual components may be present in the following amounts:

A - a compound of formula II

0.5 - 30% by weight

B - mineral · oil - 80% C - organic solvent - 30% D - surfactant

0.5 - 20% by weight

Where appropriate, other active substances suitable for combating other pests and plant diseases in the winter may also be added to the compositions of the invention.

These active substances may be insecticides, but in particular fungicides.

The mites which can be effectively controlled in the hibernating egg state using the compositions of the invention belong to the family Tetranychus (spider mite), the genera Pancnychus, Bryobia and Oligonychus.

Of these pest species, Panonychus ulml is the most important due to the extent of the damage it inflicts on plants and its widespread occurrence in all temperature zones. This pest exhibits a high degree of resistance to various pesticides almost everywhere as a result of intensive chemical interventions to which it is systematically subjected and exposed.

The amount of active agent applied to achieve the desired effect against the mite hibernating eggs may vary depending on various factors. In general, doses of between 0.1 and 3 kg / ha are sufficient.

The preparation of the compositions of the invention does not require any particular methods or measures.

In general, the active compound (the compound of formula II), the solvent and the surfactant are mixed at room temperature without the order of addition of the individual components having a role to play. Mineral oil is then added to the mixture if necessary.

The invention is illustrated by the following non-limiting examples.

Example 1

Preparation of acaricidal compositions

Representative examples of acaricidal compositions are summarized in Table 1 below. For the sake of simplicity, in Table 1, the active ingredient is designated as Ú1, the following compounds of formula II being used as these:

3)

сн _ъ

4

^ CH (CH _z) -0

7) СН ^ Сн ^ -О - ^^ - О-СН-СН-СН ^ С-СН ^ О-С

3) ch-ich ^ o - ^ - o-ch-ch-ch ^ csc-сн-о-с-Сн _ь о

9) СН- (CH _s) g0- (Oy-0-CH-CH-CH-C-C-CH-C _I 0-CH _{(CH2)) i} о

10) СН- (сн ^ о - ^^ - о-сн-сн-сн-с = С-СЧ-О-СН ^ СНхСН.,

Solvents, mineral oils and surfactants used are abbreviated as follows:

Solvents

R1 = technical xylene - commercial mixture

R2 = isobutyl alcohol

R3 = cyclohexanone

Mineral oils

МО 1 = mineral oil with a non-sulphonable content of 90% or more

MO 2 = mineral oil with an unsulioinizable content of 80 ° / q or more

Surfactants

PC 1 = mixture of polyoxyethylated nonylphenol (7 moles of ethylene oxide per mole of substrate), polyoxyethylated sorbitan oleate (20 moles of ethylene oxide per mole of substrate) and calcium dodecylbenzenesulfonate in a ratio of

4.9: 2.1: 3

PC 2 = 5: 3 mixture of polyoxyethylated nonylphenol (7 moles ethylene oxide) and sorbitan oleate (20 moles ethylene oxide)

Β 3 = 7: 3 mixture of polyoxyethylated nonylphenol (7 moles ethylene oxide) and sorbitan oleate (20 moles ethylene oxide).

TABLE 1

Acaricidal compositions (amounts of active compounds expressed in% by weight) component

2 means no.

4 5 6

1 (%) 20 May 20 May 20 May MO 1 (%) - - _ MO 2 (%) - - - R1 (%) 70 - - R2 (%) - 70 - R 3 (%) - - 70 P1 (Oo) 10 10 10 PC 2 (%) - - - PC 3 (%) - - -

10 50 5 5 20 May 2.5 - - 80 - 45 80 - - - 80 - - 80 40 7 7 25 9.5 - - - - - - _ _ _ _ _ _

The compositions in Table 1 are prepared by simply mixing the ingredients at room temperature. Compositions containing also mineral oils are prepared by mixing this oil with a mixture of the other ingredients.

Example 2

Determination of acaricidal activity on winter eggs of Panonychus ulmi

In autumn, twigs heavily infected with the above pest are cut off from apple trees grown in an orchard naturally infested with Panonychus ulmi. These twigs are then stored without any protection in natural conditions.

During the winter, small portions of particularly high egg concentration are cut off from the twigs and the number of unambiguously vital eggs is detected, removing all damaged eggs and eggs of indeterminate vitality. All these. operations are carried out in a natural unheated environment.

All test compounds are converted to suitable formulations and sprayed with 20 portions of twigs containing a total of 800 to 1000 eggs in each case.

After drying, the twigs are kept under shelter under natural conditions until the end of the test.

A few days after the hatching of eggs in the control experiment (parts of the infected twigs treated with an aqueous acetone solution and a surfactant only), the experiment is evaluated by counting no

10 - - - - - - 8 8 - 8 - - - - 10 - hatched eggs compared to the number of eggs before treatment and compared to the number of hatched eggs in the control experiment.

In the same way, the infected parts of the twigs are also treated with a commercial preparation containing parathion in mineral oil.

Table 2 below shows the potency values for Panonychus winter eggs ulmi of some of the compounds of the invention and several known compounds.

Since a certain number of mite eggs, both in the tests and in the control experiment, may change or be lost for natural indefinite reasons, the results are not reported in percentages that would be impractical from a practical point of view but in degrees of efficacy Use the following symbols:

+++ + = practically complete acaricidal efficacy +++ = high efficacy ++ · = partial efficacy + = little or no efficacy

The data in Table 2 shows that the compounds of the present invention exhibit high activity against mite winter eggs. This efficacy is high even when the compounds are applied as simple solutions in aqueous acetone and becomes virtually complete when formulated into suitable formulations, whether or not they contain formulations. mineral oil.

TABLE 2

Acaricidal activity against winter eggs Panonychus ulmi active substance ³¹ agent ^b) dose of active substance (%) acaricidal (% mineral oil) efficacy ⁰¹

Compound No. 1 aqueous acetone solution ЕС 20 Compound No. 2 ЕС 20 + mineral oil aqueous acetone Compound No. 6 solution ЕС 20 Compound No. 9 ЕС 20 + mineral oil ЕС 20 Compound No. 10 ЕС 20 + mineral oil ЕС 20 Compound A ЕС 20 + mineral oil ЕС 20 (comparative) parathion in mine- ЕС 20 + mineral oil commercial preparation mineral oil _

0.05 4 - +++ 0.01 ++ + 0.05 ++ ++ 0.01 + ’+ + + 0.01 (2) ++ ++ 0.05 + + + 0.01 ++ 0.05 + +++ 0.01 ++++ 0.01 (2) + + + + 0.05 ++++ 0.01 + + + + 0.01 (2) + + + + 0.05 ++ ++ 0.01 +++ + 0.01 (2) ++ ++ 0.05 + 0.01 + 0.01 (2) + + 0.06 (0,96) + + (2) ++

Legend:

^(a) active ingredients: compounds 1, 2, 6, 9 and 10 of the invention were identified by their formulas in Example 1; Compound A is a comparative of the formula

U.S. Patent 4,061,683;

parathion is the common name for O, O-diethyl-O-p-nitrophenylphosphorothioate;

the mineral oil is a mineral oil containing more than 80% non-sulfonatable substances. A mineral oil emulsion (80% by weight) in water is used in the tests.

^(b) ЕС 20 represents an emulsifiable concentrate containing 20% by weight of the active substance;

ЕС 20 -I mineral oil is the appropriate mixture prepared in dcba treatment;

The aqueous acetone solution is a solution or dispersion of the active ingredient in a mixture of water and acetone containing 10% by weight of acetone.

^(c) Similarly good results are obtained with the compositions of Example 1 containing other active substances of the formula II mentioned in Example 1, both with and without mineral oil.

Claims (2)

An acaricidal composition suitable for combating mites by treating hibernating ova, characterized in that it contains as active substance one or more compounds of the general formula II R-0 O ~ (CH _{I) i} -C? C-CH _í ^OR '(II) wherein R 8 represents an alkyl group having 8 to 11 carbon atoms and R "is hydrogen, alkyl having 1 to 4 carbon atoms, allyl or a radical of formula -C-R ² wherein O R ' ² is C 1 -C 4 alkyl, C 3 -C 6 cycloalkyl or phenyl. 2. A composition according to claim 1, wherein the active ingredient is one or more compounds of the above formula (II) in which: R ‘has the meaning as in point 1 a R 1 represents a hydrogen atom, a C 1 -C 4 alkyl group or a radical of the formula -C 1 -R 2 wherein O R 2 is C 1 -C 4 alkyl, C 3 -C 6 cycloalkyl or phenyl.