NO123226B - - Google Patents

Description

Fungicidal preparations.

The invention relates to compositions for destroying or combating fungi.

It was found that a satisfactory control of fungi and the like can be achieved by using compositions, which contain as the active principle compounds of the general formula:

where R is a monocyclic carboxyl group, which may be substituted and which may be attached to N via a methylene group. We have found that N-(4-methylphenyl) and N-cyclohexyl compounds are particularly effective.

The compounds can be used in the form of compositions, which contain the active ingredient and a diluent material, which can either be a solid or a liquid, depending on the way in which the composition is to be used. If the composition is to be used as a dusting preparation, the diluent may consist of talc, diatomaceous earth or another inert solid diluent. If, however, the preparation is to be in liquid form, it can be used in the form of a solution of the active ingredient in a suitable solvent, possibly in the presence of a dispersant, or it can be in the form of an emulsion or dispersion in water of the active material or a solution thereof.

It was found that such fungicide composi-

tions can be used for such purposes as the treatment and preservation of wood or timber, reconstituted wood products (such as wooden boards of different species), textiles and similar substances, which may be exposed to infection by fungi and the like. The use of the preparations to combat slime fungi, such as myxomycetes,

in cellulose factories and to preserve cellulose and wood pulp against fungal attack, is also important. An advantage of their application for industrial use is their stability and freedom from stain-forming properties. A further advantage is the simple way in which they can be produced, namely by condensation of dichloromaleic anhydride with a suitable primary amine, which means that the production costs are relatively low.

When treating plants to prevent or combat fungal attacks, the compounds according to the invention can be used in the form of foliar sprays, nebulizers and the like. We have found that the N-(4-methylphenyl) compound is particularly effective in most cases where it is necessary to use a foliar fungicide. Experiments with preparations containing N-cyclohexyldichloromaleimide show that it is particularly valuable as a general foliar fungicide.

Example 1.

Pieces of fresh pine wood with a dimension of 18 x 5 x 1.3 cm were cut out from a freshly felled tree and split lengthways, so that two plates or discs with a dimension of 18 x 5 x 0.65 cm were obtained, one of these plates served as a control sample for the other treated plate. After the two plates were separated from each other, the test pieces were immersed for 15 seconds in a solution of the compounds to be examined with respect to fungicidal activity. The compounds were diluted in acetone, so that % and 1% solutions were obtained. Sodium pentachlorophenate in water was used as a standard fungicide, as this is known as an agent to prevent rot. Ten test plates were used for each dilution and the control plate was immersed for the same time in acetone for comparison with the treated plates. For at least 2 hours the excess liquid was allowed to drain from the plates, after which they were built up in stacks of ten with 3 mm glass disc rods between each successive layer. The stacks were placed over water in aluminum dishes and incubated for 3 weeks in a closed chamber at 25°C.

Fungal growth was assessed using perspex measuring plates, which were divided into rectangles of 2.5 x 1.3 cm. The growth or spot formation in each rectangle was graded on a scale of 10 units and the total result for the 28 rectangles was calculated by addition. The result for the treated plates is converted into a percentage of the result for the control plates. No difference was made with regard to the numerical assessment between different types of staining or the different surface fungi.

The following table shows the percentage

Example 2.

A further series of experiments was carried out in a similar manner to that set out in Example 1. The solutions or dispersions of the active compound used contained 0.06%, 0.12%, 0.25% and 0.5% of the active ingredient. The standard fungicide was sodium pentachlorophenate and solutions were used containing 0.25%, 0.5%, 1.0% and 2% of fungal attack for each compound at the three concentrations used.

sodium pentachlorophenate. 10 plates were used for each dilution, as stated in example 1 to achieve a satisfactory average result and after excess liquid had been allowed to drip off the plates, and had been stacked, they were sprayed with a spore suspension of Ceratocystis pilifera. The results of these trials, expressed in percent protection achieved by means of the immersion liquid, are listed in Table 2.

Example 3.

Experiments were also carried out on a larger scale accompanied by storage over a longer period. For these experiments, fresh Scotch pine boards of dimensions 106 x 15 x 1.3 cm were used and these boards were immersed in dispersions of N-(4-methylphenyl)-dichloromaleimide, and dispersions containing 0.1% were used , 0.25% and 0.5% of the active ingredient. For comparison, similar boards were immersed in solutions containing 1% and 2% sodium o-phenylphenate. 40 tables were treated with each dilution. 20 boards from each treatment were incubated under tropical conditions in a chamber at 29°C and 95% relative humidity. The other 20 tables were stored under a plastic cover in a closed manner at outdoor summer temperatures (15-25° C). The tables were stacked in separate stacks and kept apart in the first

month of the incubation with logs, and

then they were stacked close together for another two months. The protection of the total tree excess after 1, 2 and 3 months was assessed and expressed as a percentage. The results of the experiments are shown in table 3.

Example 4-

Experiments were also carried out to determine the effect of N-(4-methylphenyl)-dichloromaleimide on the decay of timber. Air-dried sticks of pine and beech 5 x 2.5 x 1.3 cm were impregnated in vacuum with acetone solutions of 0.25 and 0.5% N-(4-methylphenyl)-dichloromaleimide and examined to determine their resistance to decay in according to the procedure described in British Standard Specification 838. For this purpose, the prepared weighed pieces are placed on mycelial mats of pure cultures of four wood-rotting fungal species and incubated at 20-22° C for 3 months. The resulting decay is measured in terms of weight loss of the oven-dried sticks. Assuming that the rods were not heated after impregnation, they were satisfactorily preserved during the trial period.

Example 5.

Experiments were conducted to determine the effectiveness of N-phenyl and N-(4-methylphenyl)-dichloromaleimides for the protection of cotton fabrics. N-(4-Methylphenyl)-dichloromaleimide was investigated in more detail using laboratory and soil burial tests on leached fabrics and/or fabrics that were exposed to the effects of the atmosphere. Neither compound was effective in preventing cotton rot of Chaetomium globosum in a laboratory experiment, but soil rot was completely prevented by 0.4% N-(4-methylphenyl)-dichloromaleimide and by 0.8% when the cloth was exposed to leaching and to the influence of the atmosphere. Powdery mildew was well controlled by 0.4% N-(4-methylphenyl)-dichloromaleimide, but only partially controlled by the same concentration of N-phenyldichloromaleimide.

The tests with regard to the resistance to powdery mildew were carried out on three strips of light cotton cloth of 7.5 x 2.5 cm, which were impregnated with a solution of the test substance in acetone. These strips or pieces were incubated on mycelial mats for three weeks at 25°C and fungal growth was determined by periodic observation of the approximate area of infection. Mycelial mats were prepared by inoculating slant cultures of 2% malt agar in bottles with a spore suspension of Aspergillus niger, Cladosporium herbarum and Penicillium italicum and the loosely stoppered bottles were incubated for 2 days at 25°C.

To carry out decay resistance tests, three strips of impregnated cloth, frayed at the edges, were incubated on mycelial mats of Chaetomium globosum for 3 weeks at 25° C. Decay was judged by visual observation and by measuring the breaking strength of the cloth before and after incubation. The mycelium mat was prepared by inoculating the slant culture of a mineral salt-containing agar with a spore suspension of Chaetomium globosum and it was incubated in closed bottles for three days at 25°C.

The soil burial experiments were carried out by burying three strips of impregnated cloth horizontally in a matured mixture of 1 part horse manure and 3 parts garden soil. Similar strips which had previously been exposed to the influence of the weather were hung in frames for 3 weeks in the open and the strips were washed out for 4 hours in running tap water and strips which had been exposed to the leaching and the influence of the weather were buried in the same way. The soil containing the strips is incubated for 17 days at 29° C in a moisture-saturated room. The resistance of the pieces of cloth to decay is measured by determining the tensile strength of the buried and non-incubated samples. After burial in this way, the untreated cloth strips were completely dissolved.

Table 4 below shows the results of these trials with preparations containing N-(4-methylphenyl)-dichloromaleimide, no results being given for N-phenyldichloromaleimide, which, although active, is not as effective as N-(4- methylphenyl)-dichloromaleimide.

Example 6.

The effectiveness of certain dichloromaleimides for controlling slime fungi in pulp and paper mills was determined on the basis of their ability to kill the slime bacteria Flavobacterium sp. and the slime mold Oospora lactis in pulp suspensions.

The experiments were carried out using a stock suspension of the test chemical prepared either by ball mill treatment overnight or by dissolving the chemical substance in acetone and dispersing it with a wetting agent. The preparation of the dispersion by treatment in a ball mill was carried out in a similar manner to that indicated in method (a) in Example 7. The suspension was serially diluted from 256 to 16 parts per million (d.p.m.) with sterile water and inoculated with a pure culture of the organisms used in the experiment. After contact periods of 3 and 24 hours under shaking, the liquids were subcultured on nutrient agar and incubated for 48 hours to determine at which dilutions the sterilization had taken place. The results of these experiments are shown in table 5.

The most active chemical substance in the above experiment, N-(4-methylphenyl)-dichloromaleimide, was added to a laboratory circulating system, which contained 0.125% pulp, 0.25% peptone and 1.0% sucrose at concentrations so that one got 8 and 16 d.p.m. in the system. The fluid was circulated at each concentration for 1 week at room temperature and the filtration rate and bacterial counts were determined as a measure of slime formation. There were no visible signs of mucus and the counts were as for the control systems and the filtration rates were much lower than for the control samples. Parallel systems treated with 2 d.p.m. of mercury, although they initially showed greatly reduced counts, produced significantly more bacteria and as much mucus as the control system within a week of the experiment.

Example 7.

Experiments were conducted to determine the effectiveness of certain of the compounds in fungicide preparations for use as a foliar fungicide. The experiments were carried out in a greenhouse and field trials were carried out for one of the preparations.

A. Greenhouse experiments.

Four diseases were used in the foliar fungicide experiments in greenhouses. These were Alternaria solani on tomatoes, Erysiphe on oats, Puccinia triticina on wheat and Phytophthora infestans on tomatoes. The procedure for testing the compounds varied slightly for each disease, but the order of the processes was the same for all diseases.

The plants were first sprayed with a dispersion of the compound to be investigated. Up to four different concentrations of each chemical substance were used, and two or three control experiments were used for each concentration. One set of control plants was sprayed with distilled water and another set with a standard comparison fungicide. After spraying or sprinkling, the plants were allowed to dry overnight. They were then inoculated with spores of the chosen appropriate pathogen and placed in an environment favorable for spore development and infection. The plants were then placed in a greenhouse for a period which allowed symptoms to develop. The assessment was then carried out and the degree of disease on the treated plants was expressed as a percentage of the disease on the control plants. The ED 95 value, i.e. the concentration required to achieve 95% control of the disease, was obtained by recording the percentage disease figures at the different spray concentrations on a logarithmic scale, and a reading of the value was obtained from the regression curve. Observation was carried out all the time of the damage due to the phytotoxicity of the compound under investigation and this damage was graded as follows: 0 — no damage 1 — very weak damage

2 — slight damage

3 — moderate damage

4 — serious injury

5 — very serious injury Table 6 indicates the small variations in the procedure, which are necessary when the different diseases are used.

The dispersions of the compound in water were obtained by grinding together in water in a ball mill an appropriate amount of the compound under investigation with either (a) an equivalent amount of the surface-active agent, which is known under the trade name "Dispersol T", or ( b) 1 part of the surfactant known under the trade name "Wafex goulac" with 25 parts of the compound under investigation. The second method, (b), of dispersion was only used with N-(4-methylphenyl)-dichloromaleimide. In all trials with Erysiphe graminis on oats, a wetting agent was added to the water dispersion of the compound before it was applied to the plants. Humectants and their final concentrations in the water dispersion applied to the plants were “Lubrol E” at 0.015%, “Tween 20” at 0.1 and 1.0% and “Agral LN” at 0.1 and 1.0%.

B. Field trials.

A field trial was carried out against Phylophthora infi slans on potato plants. The experiment was carried out in the form of randomly selected pieces. Four pieces were used for each treatment and on each piece there were three rows of wounds and they were 4.5 m long.

Four applications of N-(4-methylphenyl)-dichloromaleimide at 0.1%, dispersed in water with "Wafex goulac", and of "Perenox" (50% copper oxide) with 0.2% Cu were applied at approximately 14 day intervals. The assessment was carried out using the disease assessment key for potato blight described in Plant Pathology 1952, I, 109.

Table 8 shows the results obtained from field trials with N-(4-methylphenyl)-dichloromalcimide and the preparation containing copper oxydul which is known under the registered trademark "Perenox".

Note: The percentage disease numbers are the upper and lower limits that could be observed on four different pieces for each treatment. These figures were obtained 30 days after the last application. The disease did not appear until between 2 and 3 weeks after the last injection.

Example 8.

Foliar fungicide tests were carried out using the same compounds as in example 1 with the exception that for the standard fungicide tetramethylthiuram disulphide was used instead of sodium pentachlorophenate.

The experiments were carried out on tomato plants. The plants were first sprayed with a dispersion of the compound to be tested. The material was allowed to dry and the plant was then inoculated with Alternaria solani. This was carried out by spraying with an aqueous suspension of the fungal spores. The plants were then placed for a period of 24 hours in a room with high humidity as an incubation period. The plants were then placed in a greenhouse until disease phenomena appeared. Three plants were treated in each experiment together with three control plants, and the treatment of these differed in that they were sprayed with distilled water instead of the compound being investigated. 72 hours after inoculation, the disease damage on five main leaves of each of five leaves per plant the count. The disease count on the treated plants is converted to a percentage of the damage on the control plants. The ED 95 and ED 50 values, i.e. the concentration of the fungicide to achieve a 95% resp. 50% disease control is obtained by recording the percentage disease figures at the different applied concentrations on a logarithmic scale and the values are read from the regression curves obtained.

At all times, observations were made of the damage due to the phytotoxicity of the compound under investigation, and the damage is graded as follows: 0 — no damage 1 — very little damage

2 — minor damage

3 — moderate damage

4 — serious injury

5 — very serious damage The following table shows the results obtained at four different spray concentrations, namely 0.05, 0.01, 0.002 and 0.0004%. The dispersions of the compounds in water were prepared by grinding together in water in a ball mill an appropriate amount of the compound under investigation with an equivalent amount of the surfactant known under the trade name "Dispersol T".

The figures given show the percentage disease, the damage due to phytotoxicity, and the ED 95 and ED 50 values, i.e. the concentration of the compound necessary in each case to bring about a control of the disease of 95% or 50%.

Claims (6)

/ 1. Fungicidal preparation containing as an active ingredient a compound of the general formula: where the group R is a monocyclic carboxyl group, which may be substituted and which may be attached to N via a methylene group. 2. Fungicidal preparation as stated in claim 1, where the active ingredient is N-(4-methyl-phenyl)-dichloromaleimide. 3. Fungicidal preparation as stated in claim 1, where the active ingredient is N-cyclohexyldichloromaleimide. 4. Powdered fungicide preparation as set forth in one of the preceding claims, wherein the active compound is intimately united with an inert solid diluent. 5. Liquid fungicidal preparation as stated in one of claims 1 to 3, where the active compound is dissolved or dispersed in a suitable liquid. 6. Fungicidal preparation as stated in claim 4 or 5, characterized in that it contains a water-soluble dispersant and possibly a wetting agent.