IE51922B1 - Acaricide compositions active against hibernating eggs - Google Patents

Abstract

A method and compositions for combatting mite infestations on useful plants, by treating the hibernating (or over-wintering) eggs with a compound of the general formula: <IMAGE> in which R' represents an alkyl group having from 8 to 11 carbon atoms, R'' represents a hydrogen atom, an alkyl group having from 1 to 4 carbon atoms, an allyl group or a <IMAGE> group, in which R<2> represents an alkyl group having from 1 to 4 carbon atoms, a cycloalkyl having from 3 to 6 carbon atoms or a phenyl group.

Description

This invention relates to a method for combating acari infestations on useful plants, and in particular to a method which comprises treating the hibernating (or overwintering) eggs of mites with compounds belonging to the class of hydroquinone diethers. The invention further relates to compositions which are active against overwintering eggs of mites, containing certain hydroquinone diethers.

In evaluation the acaricide activity of a compound active against mite eggs, a distinction is made between the ovicide activity against the summer eggs and the ovicide activity against the overwintering eggs. Some mite species overwinter in the stage of eggs and these overwintering eggs are less sensitive to pesticides in comparison to summer eggs. This phenomenon is due to the state of quiescence of the embryonal life and to the fact that the chorion of the egg, which forms a barrier to the penetration of the active substance, is more resistant in the overwintering eggs to that of the summer eggs.

The known acaricide compounds include some which are active against the summer eggs of mites, others active against neanides or adult mites. However, because of the particular characteristics of the overwintering eggs of mites, most of the known acaricide compounds prove to be inactive against this kind of eggs.

There are other compounds which have proved to be only partially active and exclusively during the very short period of time close to the hatching of the eggs. The winter control of mites is generally, conducted by using formulations of phosphoric esters (in particular Parathion) in mineral oils. However, such formulations are never completely effective and it is necessary to treat in coincidence with the hatching of the eggs.

In the short period of time in which such a treatment may be useful, there are often adverse weather conditions. If treatment before the abovementioned period takes place there is little effect on winter eggs because they are particularly resistant to penetration of the pesticide. If a delayed treatment takes place it may produce the phenomena of phytotoxicity since the advanced vegetative stage of the plants is sensitive to many mineral oils.

The availability of specific products active against overwintering eggs would allow treatment to be conducted in full winter, thereby eliminating the above described difficulties and at the same time offering the advantage of not affecting the numerous species of insects useful for controlling mites (predatory insects). Moreover, from a practical point of view, the possibility of treating the cultivations in the winter time to prevent mite infestation, during which period the work on the farm tends to be limited, is a further advantage.

There does not appear to be any specific acaricide compounds commercially available which are active against the overwintering eggs of mites.

Italian Patent Applications Nos. 21003 A/80 and 26205 A/80 disclose hydroquinone diethers within the general formula: in which R represents an alkyl or an alkenyl group containing from 4 to 18 carbon atoms, X represents an oxygen atom, a -CH=CH- or a -C=C- group; m and n independently represent a positive integer from 1 to 4, Y represents an OH or SH group, an -0-R^ or -S-R^ group or an -0-C-R2 II group, in which: rT represents an alkyl group containing from 1 to 4 carbon atoms, an alkenyl or alkynyl group containing from 2 to 4 carbon atoms, and R represents an alkyl group containing from 1 to 4 carbon atoms, a cycloalkyl group containing 3 to 6 carbon atoms, or a phenyl group.

The compounds of formula (I) are endowed with acaricide activity 15 effective both on adult mites as well as on their summer eggs.

Furthermore, these compounds are endowed with practically negligible toxicity towards warm-blooded animals and fish, and they are characterised by the absence of phytotoxicity, even at high dosage rates, towards the most diffised agrarian cultivations. 61822 It has now been discovered that certain of the compounds within the scope of formula (I) are endowed with a particularly high acaricide activity against the overwintering eggs of mites.

Therefore according to the present Invention there is provided a 5 method of combating mite infestation comprising treating the over- wintering eggs of the mites with one or more of the compounds of the formula R0 ^θ^-Ο-CHg-CHg-CHg-C s C-CHg-O-R (11) in which: 10 R* represents an alkyl group having from 8 to 11 carbon atoms, R represents a hydrogen atom, an alkyl group having from 1 to 4 carbon atoms, an allyl group or a group in which p R represents an alkyl group having from 1 to 4 carbon atoms, a cycloalkyl having from 3 to 6 carbon atoms or a phenyl group.

According to a further aspect of the present invention there is provided acaricide compositions active against the overwintering eggs of mites, having as an active ingredient one or more of the compounds of formula (II).

The effectiveness of the compounds of formula (II) against the overwintering eggs is more than satisfactory for a practical use in agriculture. The compounds of formula (II) are endowed with a high acaricide activity against the overwintering eggs even at rather low doses. Furthermore, the compounds, when applied in such a manner so as to contact all the mite eggs, exert a substantially complete acaricide action and consequently the plants remain disinfected for a long period of time, e.g. for two months after the period of hatching of the eggs, thus any treatments against the adult mites which may be present later on as a consequence of re-infestations of a different origin can be delayed considerably.

The known products which have been used against the winter eggs of mites, e.g. mineral oils additioned with phosphoric esters, besides displaying the above described drawbacks regarding their application, do not possess complete acaricide action and thus, in order to obtain the same results as with the present invention, it is necessary to carry out at least two further spring treatments with acaricide products.

For practical applications in agriculture, it is better to use the compounds of formula (II) in the form of suitable compositions in order to facilitate the best possible distribution of the product so as to reach all the mite eggs which are often deposited on parts of the plants which are difficult to reach. Such compositions may comprise one or more of the compounds of formula (II) as active ingredient together with an inert carrier and a surfactant. The choice of the vehicle (carrier) and of any other additives depends on the type of formulation needed. 81933 Suitable formulations are the emulsifiable concentrates comprising the active ingredient, a liquid vehicle, e.g. an organic solvent, and one or more surfactants. Suitable organic solvents include aromatic or alkylaromatic hydrocarbons, e.g. xylol and other commercial mixtures of alkylaromatic hydrocarbons, alcohols, e.g. butyl or isoamyl alcohol, and ketones, e.g. ethyl-amyl-ketone or cyclohexanone.

Examples of suitable surfactants include alkylbenzenesulphonates, polyoxyethylated alkyl phenols, polyoxyethylated vegetable oils, glycerides of polyoxyethylated fatty acids, polyoxyethylated sorbitan oleates or mixtures thereof.

A suitable emulsifiable concentrate comprises: A) Active ingredient (compound of formula II) B) Organic solvent C) Surfactant 0.5 to 50% by weight 30 to 80% by weight 0.5 to 20% by weight.

It is known that mineral oils possess a certain activity against the overwintering eggs of mites. Such activity, which is not very pronounced, is essentially of a physical character, in as much as the oils may cover the mite eggs with a very thin film thus hindering the gaseous exchanges which may result in the death of the embryo. Thus, in the above described compositions mineral oil may have the functions both of vehicle and as an additional active substance.

Suitable mineral oils include commercial oils having a content in unsulphonable substances of at least 80%. Suitable solvents and surfactants are those described above.

Formulations incorporating mineral oil may comprise the components in the following ranges: A) Compound of formula (II) 0.5 to 30% by weight B) Mineral oil 40 to 80% by weight C) Organic solvent 5 to 30% by weight D) Surfactant 0.5 to 20% by weight Whenever a special situation should require it, it is possible to include other active substances useful for the winter control of other plant pests and diseases. Such active substances include insecticides and in particular fungicides.

The acari species that may be effectively controlled in the stage of overwintering eggs according to the invention belong to the family of Tetranychidae, genera: Panopychus, Bryobia and Oligonychus.

Amongst these species, the most important one from the extent of the damage inflicted to plants and from the wide distribution in all temperate areas, is Panopychus ulmi which generally shows a high level of resistance to the different pesticides due to the intensive chemical attack to which it has been systematically subjected.

The amount of active substance to be distributed in order to ensure an effective action against the overwintering eggs of mites, may vary depending on different factors. In general, amounts comprised between 0.1 and 3 Kg/ha are quite sufficient.

The preparation of the compositions of the present invention does not require any particular procedure.

The active ingredient (compound of formula II), the solvent and the surfactant are mixed together without any preferred order at room temperature. To this mixture the mineral oil is admixed when necessary. 51822 The invention will now be illustrated by the following Examples.

Example 1 Preparation of acaricide compositions The acaricide compositions reported in the following Table 1 were prepared by simple admixture of the recited components at room tempetature. In the case of those compositions containing mineral oil, the latter was admixed to a mixture of the other ingredients. lg In Table 1, the following abbreviations have been used: a.i. = active Ingredient the following compoundsof formula (II) were used as the active ingredient. 1) ch3-(ch2)9-o-^0>- o-ch2-ch2-ch2-c=c-ch2-o2) ch3-(ch2)i0-0^O^0-ch2-ch2-ch2-c=c-ch2-0CH, 3) CH3-(CH2)?-0 O-CH -CH -CH -C= C-CH -O-CH-CH 2 2 2 2 6h33 4) ch3- ( ch2 ) 7 o-ch2-ch2-ch2-c = c-ch2-o-ch. ) ch3-(ch2)7-0-^0^· o-ch2-ch2-ch2-c=c-ch2-o-ch2-ch3 6) CH3-(CH2)g-0-< 0)= 0-CHo-CH5-CHo-CBC-CH9-0H 7) CH3-(CH2) g-O’^O^- O-CH2-CH2-CH2-C= C-CH,, 8) ch3-(ch2)9-o-^O^o-ch2-ch2-ch2-c=c-ch2-o-c-ch39) ch3-(ch2)9 0®· O-CH -CH -CH -C= C-CH -O-C-CH(CH )n 2 2 2 2 μ 3 2 ) CH3-(CH2)9-O-^y_,O-CH-CH-CH-C”)C-CH-O-CH-CH=CH 2 2 2 2 2 2 51933 Solvents Sol 1 = xylol, commercially available mixture have been used Sol 2 = isobutyl alcohol Sol 3 = cyclohexanone.

Mineral Oils MO 1 = mineral oil with a content of unsulphonable substances of at least 90% MO 2 = mineral oil with a content of unsulphonable substances of at least 80% Surfactants Sur 1 = Mixture of polyoxyethylated nonyl-phenol (7 moles of ethylene oxide per mole of substrate), polyoxyethylated sorbltan-oleate (20 moles of ethylene oxide per mole of substrate) and calcium dodecylbenzenesulphonate in the ratio 4.9:2.1:3.

Sur 2 = Mixture of polyoxyethylated nonyl-phenol (7 ETO) and sorbitan-oleate (20 ETO) In the ratio 5:3.

Sur 3 = Mixture of polyoxyethylated nonyl-phenol (7 ETO) and sorbitan-oleate (20 ETO) in the ratio 7:3.

Table 1 Acaricide compositions (amounts of components expressed as percentage by weight) Composition No.

Components 1 2 3 4 5 6 7 8 9 a.i. (%) 20 20 20 10 SO 5 5 20 2.5 MO 1 (%) - - - - - 80 - 45 80 MO 2 (%) - . - - - - 80 - - Sol 1 (%) 70 - - 80 40 7 7 25 9.5 Sol 2 [%} - 70 - - - - - - - Sol 3 (%) - - 70 - - - - - - Sur 1 (%) 10 10 10 10 10 - - Sur 2 (%) - - - - - 8 8 - 8 Sur 3 (%) - - - - - - 10 * Example 2 Determination of the acarlcide activity on winter eggs of Panonychus ulmi Twigs heavily infested with £. ulmi eggs were cut off in autumn from apple trees grown in an orchard naturally infested by mites. The twigs were kept in the open under natural conditions.

During the winter, operating in an unheated environment, small portions on which the presence of eggs was particularly concentrated were cut from the twigs and for each of these portions the number of eggs that were clearly vital were counted and all the damaged eggs and those of uncertain hatching were removed. Each of the compounds under investigation were incorporated into suitable compositions and formulations, and applied by spraying to twenty twig-portions carrying 800 to 1,000 eggs in total. After drying,the twig portions were kept in the open under a shelter in natural conditions until the conclusion of the test.

The results were assessed several days after the end of the hatching of the eggs in a control sample (portions of infested twigs treated only with a water-acetone solution and a surfactant), by counting the unhatched eggs in comparison with the eggs present before the treatment and taking into account the unhatched eggs in the control. 51923 Adopting the same procedure, infested twig portions were also treated with a commercial formulation containing Parathion in mineral oil.

Table 2 reports the activity data against winter eggs of 5 Panonychus ulmi of some compounds in accordance with the invention compared to known compounds.

A certain number of mite eggs, both in the test and in the control may have been effected or missing for natural undefined causes and accordingly the results have been expressed by classes of activity rather than by actual percentage values which would not be suitable for the practical character of the experiment. The classification system applied was as follows: ++++ = practically complete acaricide activity +++ = high activity ++= partial activity + = negligible or no activity.

The data reported in Table 2 shows that the compounds used in the invention possess a high activity against mites winter eggs. 2Q The activity is high even when the compounds are used as simple water-acetone solutions and becomes substantially completely effective when the compounds are formulsited independently of the presence of a mineral oil.

Table 2 Acaricide activity against £. ulmi winter eggs Active ingredient Formulation Dose a.i. (%) p min. oi ij Acaricide activity Compound No. 1 water-acetone solution 0.05 0.01 ++++ +++ EC 20 0.05 0.01 ++++ ++++ EC 20 + mineral oil 0.01 [2] ++++ Compound No. 2 water-acetone solution 0.05 0.01 +++ ++ Compound No. 6 EC 20 0.05 0.01 ++++ ++++ EC 20 + mineral oil o.oi [2] ++++ Compound No. 9 EC 20 0.05 0.01 ++++ ++++ EC 20 + mineral oil o-oi [z] ++++ Compound No. 10 EC 20 0.05 0.01 ++++ ++++ EC 20 + mineral oil 0.01 [2] ++++ Compound A (Comparative) EC 20 0.05 0.01 + + EC 20 + mineral oil o.oi [2] ++ Parathion in mineral oil (Comparative) Commercial formulation 0.06 [θ.96] ++ Mineral oil (Comparative) - ++ Notes to Table 2 (a) Active ingredients Compounds 1, 2, 6, 9 and 10 are as defined in Example 1. Compound A is a comparative compound of the formula 0- CH2-CH2-CH2-C = CH (A) according to United States Patent Specification No. 4 061 683.

Parathion is the common name of the compound 0,0-di ethyl-0-p-ni trophenyl-phosphorothioate.

Mineral oil is a mineral oil having a content of unsulphonable substances of at least 80%. An emulsion of mineral oil (80% by weight) in water was used in the tests. (b) EC 20 means emulsifiable concentrate at 20% by weight of active ingredient.

EC 20 + mineral oil is a mixture prepared at the moment of the treatment. 15 Water-acetone solution is a solution or dispersion of the active ingredient in a water-acetone mixture (acetone. 10% by weight). (c) Comparable results have been obtained by using compositions according to Example 1 and containing the other active compounds of formula (II) listed in Example 1, both with mineral oil and without.

Claims (20)

1. A method for combating mite infestation comprising treating the overwintering eggs of the mites with one or more of the compounds of the formula: o-ch 2 -ch 2 -ch 2 -c=c-ch 2 -o-r (II) in which R 1 represents an alkyl group having from 8 to 11 carbon atoms, R“ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an allyl group or a ,o r 2 group in which R^ represents an alkyl group having from 1 to 4 carbon atoms, a cycloalkyl having from 3 to 6 carbon atoms or a phenyl group.

2. A method as claimed in Claim 1, in which the compound of 15 formula (II) is applied in a composition containing an inert carrier, a surfactant and optionally a mineral oil.

3. A method as claimed in Claim 2, in which the compositions is obtained from an emulsifiable concentrate in which the carrier is an organic solvent. 20

4. A method as claimed in Claim 3, in which the emulsifiable concentrate comprises: A) Compound of formula (II) B) Organic solvent C) Surfactant

5. A method as claimed in 5 concentrate comprises: A) Compound of formula (II) B) Mineral oil C) Organic solvent 0) Surfactant 0.5 to 50% by weight 30 to 80% by weight 0.5 to 20% by weight. Claim 3, in which the emulsifiable 0.5 to 30% by weight 40 to 80% by weight 5 to 30% by weight 0.5 to 20% by weight. 10 5. A method as claimed in any one of Claims 3 to 5, in which the organic solvent is an alkyl-aromatic hydrocarbon, alcohol or ketone.

6. 7. A method as claimed in any one of Claims 3 to 5, in which the surfactant is an alkylbenzenesulphonate, polyoxyethylated alkylphenol, polyoxyethylated vegetable oil, polyoxyethylated sorbitan-oleate or 15 any combination thereof.

7. 8. A method as claimed in any one of Claims 3 to 7, in which the mineral oil is a mineral oil having a content of unsulphonable substances of at least 80%.

8. 9. A method as claimed in any preceding claim, in which the mites 20 belong to the family Tetranychidae, genera: Panonychus, Bryobia and Oligonychus.

9. 10. A method as claimed in Claim 9, in which the mites belong to the species Panonychus ulmi. 51822

10. 11. A method for combating mite infestations as claimed in Claim 1 substantially as herein described with reference to either Example.

11. 12. An acaricide composition suitable for fighting mite infestations by treatment of the overwintering eggs containing as 5 active ingredient one or more of the compounds of the formula: R'-O 0-CH 2 -CH 2 -CH 2 -C»C-CH 2 -0-R (II) in which R 1 represents an alkyl group having from 8 to 11 carbon atoms, R represents a hydrogen atom, an alkyl group having from 1 to 4 carbon atoms, an allyl group or a -C-R 2 ll group in which p R represents an alkyl group having from 1 to 4 carbon atoms, a cycloalkyl having from 3 to 6 carbon atoms or a phenyl group.

12. 13. An acaricide compositions as claimed in Claim 12, containing a compound of formula (II) together with an inert carrier, a surfactant and optionally a mineral oil.

13. 14. An acaricide composition as claimed in Claim 13, in the form of an emulsifiable concentrate in which the carrier is an organic solvent.

14. 15. An acaricide composition as claimed in Claim 14, comprising : 519 22 A) Compound of formula (II) 0.5 to 50% by weight B) Organic solvent C) Surfactant 30 to 80% by weight 0.5 to 20% by weight.

15. 16. An acaricide composition as claimed in Claim 14, comprising: A) Compound of formula (II) 0.5 to 30% by weight B) Mineral Oil C) Organic solvent 0) Surfactant 40 to 80% by weight 5 to 30% by weight 0.5 to 20% by weight.

16. 17. An acaricide composition as claimed in any one of Claims 14 to 16, in which the organic solvent is an alkyl-aromatic hydrocarbon, an alcohol or a ketone.

17. 18. An acaricide composition as claimed in any one of Claims 14 to 17, in which the surfactant is an alkylbenzenesulphonate, polyoxyethylated alkylphenol, polyoxyethylated vegetable oil, polyoxyethylated sorbitan-oleate or any combination thereof.

18. 19. An acaricide composition as claimed in any one of Claims 14 to 18, in which the mineral oil is a mineral oil having a content of unsulphonable substances of at least 80%.

19.

20. An acaricide composition suitable for fighting mite infestations substantially as herein described with reference to either Example.