GB2169511A - Quaternary ammonium microbicides - Google Patents

Abstract

Microbicidal agents for the control of phytopathogenic bacteria and fungi in pomiculture, horticulture, agriculture, and in decorative and meadow thicket, contain quaternary ammonium bactericides of formula <IMAGE> in which n is 1-20, X is halogen and R1 and R2 are each H, C1-4 alkyl or C1-4 hydroxyalkyl. The quaternary ammonium compounds may be used in admixture with fungicides selected from benzimidazoles or benzimidazole formers, phthalinides, alkyl-morpholines or dithiocarbamates.

Description

SPECIFICATION Agents for the Control of Phytopathogenic Bacteria and Fungi The invention describes microbiocide agents for the control of phytopathogenic bacteria and fungi in pomiculture and horticulture, agriculture and on ornamental and meadow thickets or woody plants. The active ingredients in the agents are bacteriocidesfrom the compound class of the quaternary ammonium compounds with the general formula

in which R1 and R2 are hydrogen, alkyl radicals or hydroxyalkyl radicals with C1-C4 carbon atoms, CnH2n+1 is an alkyl radical with 1 to 20 carbon atoms, and xis halogen for example chlorine, bromine or iodine and which are produced and used, if necessary in a mixture with fungicides from the class of benzimidazoles or benzimidazole formers, phthalimides, alkyl-morpholines or dithiocarbamates. The aim of the invention is to prevent microbial disease in cultivated plants during the vegetation period.

The invention relates to microbiocide active components whose formulation and combination serves to control bacteria and fungi in pomiculture, horticulture, agriculture and outdoor meadow thicket. The agents according to the invention can be used either before, during or after the vegetation period of the cultivated plants, bushes or thickets to control bacterial or fungal diseases.

There are hardly any means for controlling bacterial disease in plants available on an international scale. Bacteriocides, which enable rapid control of disease in fruit orchards, which act specifically and which can be applied without toxicological hazard, have not previously been available on a world-wide scale.

The control of bacterial disease in pomiculture, horticulture, agriculture and decorative and meadow thicket has become increasingly important following the epidemic spread of bacterial disease on the European continent within the last 20 years. While fungicidal agents with chloramphenicol (East German Patent No. WP 78423 and East German Patent No. WP 84958 as patent of addition, East German Patent No.

WP 107 204 and East German Patent No. WP 110423 as patent of addition) or Bronopol (East German Patent No. WP 133 885) are used to control bacterial rot during storage of potatoes and types of head cabbage, such preparations have not been available in pomiculture. Rather, the opportunities for the rapid spread of disease in the stocks caused by insects, rain splashes or cultivation methods have often caused orchards to be cleared and burnt on a large scale.

Chemical means for disinfecting wounds in plants and cutting tools with means containing mercury chloride or cresol or tar, mercury cyanide, sodium hypochlorite or lysol either did not have the required results or were not to be recommended from a toxicologicai point of view. Copper preparations were used very early on and are still used today to prevent infection of blossoms. However, it was disadvantageous that copper compounds caused considerable rust disease in leaves and fruit.

Organic fungicides have only a limited bacteriocidal effect. However, it is only possible to suppress bacterial disease using Mancozeb, Thiram or Maneb, wherein there are regional differences in the European countries with regard to use.

Antibiotics such as penicillin, streptomycin, terramycin, agrimycin, tetracycline, and so on, proved to be promising, especially streptomycin which achieved considerable importance. The frequent use of antibiotics, however, led within a short time to streptomycin-resistant strains (Crosse, J. E.: "Prospects for the use of bacteriocides for the control of bacterial disease". 6. Brit. Insect. & Fungicid. Conf. 1971 in Brighton, Proceedings 1971,694 . . . 705), so that increasing use was once again made of copper agents or combinations of copper agents with antibiotics (Moller et al: Fireblight, Streptomycin-Resistant Control Studies, 1971 Calif. Agric. 27 (1973), H 6, P. 4--5).

From the point of view of human medicine, the use of antibiotics in phytopathology has been rejected for various reasons in order not to increase the problems of resistance in human medicine by way of residues in foodstuffs. Economic reasons also limit the use of antibiotics. The frequently taken step of removing the diseased thickets by clearing or chemical elimination using preparations containing 2,4 D and 2,4,5 T, or Fosamin or Glyphosate is often unjustifiable for economical and/or toxicological reasons or from the point of view of environmental protection.

It is known that quaternary ammonium compounds have strong bacteriocidal properties and are used as disinfection agents in human medicine.

It is further known that quaternary ammonium compounds have an algicidal effect (USA Patent No.

3 166 471, Belgium Patent No. 1120 523) and can be used for this purpose in combination with carbamide herbicides (East German Patent No. WP 158 502). It is still further known that quaternary ammonium compounds have a considerably wide range of effect against bacteria and fungi in the disinfection field and also work very well against alternaria and botrytis fungi (Witek et al: East German Patent No. WP 140 403.9.

The aim of the invention is to prevent bacterial disease in cultivated plants, fruit and decorative plants during vegetation as well as the spread of this disease through infection of the blossoms or cultivation methods and simultaneously to enable production of trees or decorative plants by eliminating the primary infection, and to preserve existing planted stands in recreation areas, in grassed areas and roadside areas as well as meadow thickets. Atthe same time, these agents should be sufficiently compatible with plants. It is also intended to combine the bacteriocidal effect with a fungicidal effect and thus to increase the range of application.

It has been found that quaternary ammonium compounds with the general formula

in which R, +R2 are hydrogen, alkyl radicals or hydroxyalkylradicals with C1-C4 carbon atoms, CnH2n+1 is an alkyl radical with 1 to 20 carbon atoms, and xis halogen for example as chlorine, bromine or iodine, can overcome, together with fungicides, the defects of the previously known technical solutions. The agents according to the invention suitable for controlling bacterial and fungal pathogens in pomiculture, horticulture and agriculture and ornamental and meadow thickets.

Once the active agents have been formulated accordingly, they can be applied by means of dusting, sprinkling, spraying, immersing or other suitable methods.

Thus the following technical problems in known solutions can be avoided: - clearance of affected thickets - saving of 5 . . . 15 applications in the case of antibiotics - resistance problems - clearance of hawthorn hedges near orchards destruction of bee colonies near sources of infection - yield losses over longer periods of time.

Embodiments The following examples illustrate the invention without limiting it: 1. The quaternary ammonium compound benzalkonium chloride (BAC) with an average length of chain of n=15 in which R1 +R2 are methyl radicals was tested as a 50% concentrate for its suitability for disinfecting work tools. For this purpose, the surface of conventional tools was contaminated with exciter germs, then disinfected with BAC and 1,000 cuts were made. The results of the disinfection are shown in Table 1.

2. In order to prevent a blossom infection by Erwinia amylovora, blossoms were prophylactically treated with benzalkonium chloride and then contaminated with an exciter suspension.The blossoms were externally sterilized and checked for infection by Erwinia amylovora with the aid of a culture medium. The results are shown in Table 2.

3. Preventing the flowering of decorative thickets is an important and completely new means of preventing the spread of infection. For this purpose, 500 buds were treated with the biocide according to the invention. The number of blossoms opening was recorded. The results are listed in Table 3.

4: In further extensive tests, it was possible to determine that the biocide according to the invention is suitable for achieving a quantitatively higher degree of propagation of shoots in thickets. For this, thickets of the same kind and age were treated at the time of flowering with benzalkonium chloride, and the number of shoots which were suitable for nursery plants were counted and compared with untreated thickets. The results are given in Table 4 and clearly show that the biocide in accordance with the invention can be used for chemical cutting (pruning) and to increase the production of nursery plants.

TABLE 1 Efficacy of Benzalkonium Chloride for the bisinfection of Work Tools with Reference to Erwinia Amylovora Fruit Tree Secateurs (Coated) Biocide Immersion Wiping Spraying BAC 1% BAC 5% Key: very good effect +++ good effect ++ no effect -.

TABLE 2 Effect of BAC for Prevention of Blossom Infection by Erwinia Amylovora (n=50 Blossoms) Number of Affected Blossoms Biocide 1x104 Density of Suspension 1 X109 BAC 50 ppm 0% 0% BAC 10 ppm 14% 22% Control 60% 100% TABLE 3 Efficacy of the Biocide for the Prevention of Flowering (n=500) Number of Open Blossoms Concentration Untreated Thicket 2% 2.5% 3% Control Hawthorn 12 8 10 500 Fire thorn 2 0 1 500 TABLE 4 Number of New Shoots after Treatment with 20% BAC Untreated Pyracantha Test Control 2% BAC 1 6 15 2 5 21 3 6 17 4 8 18 5 10 25 TABLE 5 Effect of the Preparation on a Bacteria Suspension of Varying Germ Density Concentration of Time to Take Effect the Preparations Immediate 1 min. 5 min. Immediate 1 min. 5 min.

Exciter % 2x109 Germs/ml 2x104 Germs/ml Corynebakterium 1 + + + + + + michiganense 2 + + + + + + p.v. michiganense 5 + + + + + + Bacillus subtilis 1 - - - - - 2 - - - - - 5 - - - - - Pseudomonas 1 - - - - - + syringae 2 - - + + + + 5 - - + + + + Erwinia 1 + + + + + + amylovora 2 + + + + + + 5 + + + + + + Key: + Preparation effective - Preparation ineffective.

TABLE 6 Efficacy of the Preparation 'In-Vitro (Plate Test) Concentration of the Preparation Exciter 1000 ppm 500 ppm 100 ppm Erwinia amylovora + + Pseudomonassyringae + + pr. tomato Corynebakterium +++ ++ ++ michiganense pr. michiganense Bacillussubtilis ++ ++ ++ Key: - no areas of inhibition + small areas of inhibition ++ average areas of inhibition +++ large areas of inhibition.

Claims (5)

1. Agents for controlling phytopathogenic bacteria and fungi particularly in pomiculture, horticulture and agriculture and in decorative and meadow thickets or woody plants, which contains, in addition to conventional solvents and formulation aids, quaternary ammonium compounds of formula I

in which R1 and R2 each separately represent hydrogen, alkyl radicals or hydroxyalkyl radicals having C1-C4 carbon atoms CnH2n+, represents an alkyl radical having from 1 to 20 carbon atoms and x represents halogen for example chlorine, bromine or iodine.

2. Agents as claimed in claim 1, in which the quaternary ammonium compounds comprise a mixture of homologous alkyl-dimethyl-benzyl-ammonium chlorides (benzalkonium chlorides).

3. Agents as claimed in claim 2, in which the benzalkonium chlorides are present in aqueous solution.

4. Agents as claimed in any of claims 1 to 3, in which there is also present one or more fungicides from the class of benzimidazoles or benzimidazole formers, phthalimides, alkyl-morpholines or dithiocarbamates.

5. Agents according to claim 1 substantially as hereinbefore particularly described.