GB1569013A - Prevention and eradication of fungal infections and diseases - Google Patents

Abstract

The fungicidal composition according to the invention contains, as at least one active ingredient, a compound of the formula I <IMAGE> in which R denotes a hydrogen atom or a methyl group. The fungicidal composition according to the invention can be used for controlling downy mildew infections in plants, caused by the fungal family of the Peronosporaceae, and for the treatment of crown and root rot caused by soil fungi from the genus Phytophthora.

Description

(54) PREVENTION AND ERADICATION OF FUNGAL INFECTIONS AND DISEASES (71) We, CHEVRON RESEARCH COMPANY, a corporation duly organized under the laws of the State of Delaware, United States of America, of 575 Market Street San Francisco, California 94105, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to the control of fungal infections and is particularly concerned with controlling downy mildew fungal infection on plants caused by Peronsporaceae fungi or crown or root rot diseases caused by soil:inhabiting Phytophthora fungi.

U.S. Patent No. 3,993,860, issued to David Cheong King Chan on January 26, 1976, and U.S. Patent No. 4,012,519, issued to David C eong King Chan on March 15, 1977, disclose the use of a large class of 3-(N-acyl-N-arylamino) lactones and 3 (N-acyl-N-arylamino) lactams as protectant fungicides. These patents do not teach curative or eradicant fungicidal activity for any of the 3-(N-acyl-N-arylamino) lactones or lactams disclosed in the patents.

U.K. Patent No. 1,445,387, published August 11, 1976, and U.S. Patent No.

4,015,648, issued May 24, 1977 to H. Moser, disclose the use of N (methoxycarbonylethyl)-N-haloacetylanilines as preventive and curative funigicides. It has been found by comparative testing that a compound of the subject invention is substantially more effective as an eradicant or curative fungicide than the fungicides of these patents.

German Patent Publication Nos. 2,643,403 and 2,643,445, published April 7, 1977, disclose the use of N-(alkylthio-carbonethyl)acetanilides for controlling fungi, particularly those of the class Phycomycetes.

Netherlands Patent Publication No. 152,849, published April 15, 1977, discloses the use of N-(alkoxymethyl)acetanilides as fungicides. it has been found that fungicidal compositions containing 3-(N-chloroacetyl N-2,6-dimethylphenylamino)-gamma-butyrolactone or 3-(N-chloroacetyl-N-2,6 dimethylphenylamino)-5-methyl-gamma-butyrolactones are effective for the control of downy mildew diseases and Phytophthora crown and root rot diseases.

The compositions employed in the invention are effective both as protectant fungicides, i.e., they prevent or protect against fungal infections, and as eradicant fungicides, i.e., they eliminate and cure established infections. As described in more detail hereinbelow, the finding of eradicant activity for the fungicidal compositions of the present invention is highly advantageous. The compositions of the invention are especially preferred for the control of grape downy mildew because it has been found that they do not inhibit the fermentation of grapes harvested from grapevines treated with the compounds of the invention. Also, it has been discovered that the compositions of the present invention have surprisingly high effectiveness for eradicating grapevine downy mildew and that grapevine downy mildew fungi do not appear to develop resistance to the comnositions.

The fungicidal compositions of the invention contain as the active ingredient a fungicidally effective amount of a compound represented by the formula

wherein R is hydrogen or methyl.

The compounds of formula (I) are described in U.S. 3,933,860.

The fungicidal compositions of the invention are highly effective for the control of plant downy mildew diseases caused by fungal species of the Peronosporaceae family and plant crown and root rots caused by soil-inhabiting fungal species of the Phytophthora genus.

Downy mildew is a widely distributed group of diseases of plants grown in the cool, humid areas of the world. Downy mildew diseases include downy mildew of lettuce caused by the species Bremia lactucae; downy mildew of spinach caused by the species Peronospora effusa; downy mildew of onions caused by the species p. destructor; downy mildew of soybeans caused by the species p. manshurica urica; downy mildew of broccoli caused by the species p. parasitica; downy mildew of cabbage caused by the species p. parasitica ssp. brassicae; downy mildew of tobacco caused by the species p. tabacina; downy mildew of alfalfa caused by the species p. trifolorium; downy mildew of sugar beets caused by the species p. schactit; downy mildew of lima beans caused by the species Phytophthoraphaseoli; downy mildew of grapevines caused by the species Plasmopara viticola; downy mildew of watermelon, cucumber, squash and related plants caused by the species Pseudoperonospora cubensis; and downy mildew of hops caused by the species Pseudoplasmopara humili.

Soil-inhabiting Phytophthora fungi cause a variety of crown and root rot diseases in plants. They are extremely difficult to control by fungicides because of the soil habitat of the fungus. Soil treatment to control the fungus is not generally effective, because many fungicides are not effectively distributed in soil and/or are detoxified in soil. Soil-inhabiting fungi can be controlled by downward systemic fungicides, i.e., a fungicide which translocates down to the roots of a plant after application of the fungicide to the plant foliage. However, most fungicides effective for the control of Phtophthora fungi do not possess downward systemic activity. The fungicides of the invention are systemic upward from the roots to the foliage and downward from the foliage to the roots. The fungicides of the invention are also not detoxified by the soil and are rapidly taken up by the roots of plants. Therefore the fungicides of the invention are highly effective for the control of soil-inhabiting Pkvwphthorn fungi.

Phywphthora species causing crown and root rot diseases in plants include Pkvwphthora cactorum (crown rot of walnut, root rot of sweetcloves, root cankers of avocado trees, Phytophthora rot of apples and pears); p cambivorn (ink disease of citrus trees); p. capsici root rot of peppers); p. cinnamoni (heart and root rot of pineapples, Phytophthora root rot of avocadoes, root rot of citrus trees);p. citricola (brown rot gummosis); p citrophthora (root rot of citrus trees); p. cryptogea (crown and root rot of tomato, safflower and tobacco); p. dreschleri (root rot of safflower); p. erythrosytica (pink rot of potato); p. fragariae (red stele of strawberry); p. megosperma (root rots of cherry, peach and walnuts); p. nicotianae (tobacco black shank): p. palmivora (root rot of citrus trees, bud rot of coconut palm, black pod rot of cacao); p. parasitica (root rot of watermelons, root rot of citrus trees); and p. syringe (root rot of citrus).

The fungicidal compositions of the invention are particularly useful fungicides because they cure established fungal infections. This permits economical use of the fungicides of the invention, because they need not be applied to plants unless fungal infection actually occurs. Thus, a preventative program of applying fungicides against potential fungal infection is not necessary.

Protectant or preventive fungicides and eradicant fungicides generally operate by completely different modes of action. For example, protectant or preventive fungicides generally prevent fungal infection by preventing sporulation and/or infection, whereas eradicant fungicides cure fungal diseases after the host is already infected. Therefore, it is highly surprising that the fungicides of the present invention act as both protectant and eradicant fungicides.

The compositions of the invention are applied in fungicidally effective amounts to fungi and/or their habitats, such as vegetative plant hosts and their growth medium or environment. The amount used will, of course depend on several factors such as the host, the species of fungus and the particular composition of the invention. The fungicidal compositions of the ivention generally contain conventional, biologically inert extenders or carriers normally employed for facilitating dispersion of the active fungicidal ingredient, recognizing that the formulation and mode of application may affect the activity of the fungicide. Thus, the fungicidal composition of the invention may be granules, powdery dusts, wettable powders, emulsifiable concentrates, solutions, or any of several other known types of formulations, depending on the desired mode of application.

Wettable powders are in the form of finely divided particles which disperse readily in water or other dispersant. These compositions normally contain from about 580% fungicide, and the rest inert material, which includes dispersing agents, emulsifying agents and wetting agents. The powder may be applied to the soil as a dry dust, or preferably as a suspension in water. Typical carriers include fuller's earth, kaolin clays, silicas, and other highly absorbent, wettable, inorganic diluents. Typical wetting, dispersing or emulsifying agents include, for example: the aryl and alkylaryl sulfonates and their sodium salts, alkylamide sulfonates, including fatty methyl taurides; alkylaryl polyether alcohols, sulfated higher alcohols and polyvinyl alcohols; polyethylene oxides, sulfonated animal and vegetable oils; sulfonated petroleum oils; fatty acid esters of polyhydric alcohols and the ethylene oxide addition products of such esters; and the addition products of long-chain mercaptans and ethylene oxide. Many other types of useful surfaceactive agents are available in commerce. The surface-active agent, when used, normally comprises from 1% to 15% by weight of the fungicidal composition.

Dusts are freely flowing admixtures of the active fungicide with finely divided solids such as talc, natural clays, kieselguhr, pyrophyllite, chalk, diatomaceous earths, calcium phosphates, calcium and magnesium carbonates, sulfur, lime, flours, and other organic and inorganic solids which act as dispersants and carriers for the toxicant. These finely divided solids have an average particle size of less than about 50 microns. A typical dust formulation useful herein contains 75% silica and 25% of the toxicant.

Useful liquid concentrates include the emulsifiable concentrates, which are homogeneous liquid or paste compositions which are readily dispersed in water or other dispersant, and may consist entirely of the fungicide with a liquid or solid emulsifying agent, or may also contain a liquid carrier such as xylene, heavy aromatic naphthas, isophorone, and other non-volatile organic solvents. For application, these concentrates are dispersed in water or other liquid carrier, and are normally applied as a spray to the area to be treated.

Other useful formulations for fungicidal applications include simple solutions of the active fungicide in a dispersant in which it is completely soluble at the desired concentration, such as acetone, alkylated naphthalenes, xylene, or other organic solvents. Granular formulations, wherein the fungicide is carried on relatively coarse particles, are of particular utility for aerial distribution of for penetration of cover-crop canopy. Pressurized sprays, typically aerosols wherein the active ingredient is dispersed in finely divided form as a result of vaporization of a low-boiling dispersant solvent carrier, such as a Freon (the word "Freon" is a Trade Mark) may also be used. All of those techniques for formulating and applying fungicides are well known in the art.

The percentages by weight of the active fungicide may vary according to the manner in which the composition is to be applied and the particular type of formulation, but in general comprise 0.5 to 95% of the active fungicide by weight of the fungicidal composition.

The fungicidal compositions may be formulated and applied with other active ingredients, including other fungicides, insecticides, nematocides, bactericides. plant growth regulators, fertilizers, etc.

EXAMPLES The preparation, formulation and use of the fungicidal compositions of the invention are illustrated by the following examples.

Example 1 - Preparation of 3-(N-chloroacetyl-N-2.6-dimethylphenylamino)-gamma- butyrolactone (Compound A) A solution of 410 g (2 mols) N-2,6-dimethylphenylamino-gammabutyrolactone, m.p. 85-86.50C, and 197.5 g (2.5 mols) pyridine in 2 liters benzene was heated to reflux. To the solution was added dropwise 260 g (2.3 mols) chloroacetyl chloride over a 40-minute period. The reaction mixture was heated under reflux for 20 additional minutes, cooled and filtered to remove a precipitate of pyridine hydrochloride. The filtrate was washed with water, dried over magnesium sulfate and evaporated under reduced pressure to give a colorless white solid. The solid was slurried with isopropanol, filtered, and dried to give 501 g of product, as a colorless solid, m.p. 145.5 -- 1470C.

The product has an oral LDso (rats) of > 1000 mg/kg and dermal LD50 (rats) of > 2000 mg/kg.

Example 2 -- Preparation of 3-(N-chloroacetyl-N-2 6-dimethyiphenylamino )-5-methyl- gamma-butyrolactone (Compound B) A 500-ml round-bottom flask equipped with a two-way stopcock was charged with 24.2 g (0.2 mol) 2,6-dimethylaniline and 19.0 g (0.106 mol) alpha-bromogamma-valerolactone. The flask was evacuated to 20 mm of Hg, then slowly heated to 1000C while periodically evacuating the flask by means of a water-aspirator to maintain the pressure at about 1740 mm of Hg. After heating the reaction mixture at about 100"C and at 17---40 mm of Hg for 22 hours, the reaction mixture was cooled and diluted with 300 ml ethyl ether. A solid precipitate of 2,6-dimethylaniline hydrobromide salt was removed by filtration. The filtrate was washed with 5% aqueous hydrochloric acid solution, water, dried over magnesium sulfate and evaporated under reduced pressure to give 19.2 g of 3-(N-2,6dimethylphenylamino)-5-methyl-gamma-butyrolactone, as a viscous oil.

A 10.9-g (0.096-mol) sample of chloroacetyl chloride was added slowly to a solution of 19.2 g (0.088 mol) 3-(N-2,6-dimethylphenylamino)-5-methyl-gammabutyrolactone and 7.6 g (0.096 mol) pyridine in 250 ml ethyl acetate. An exotherm ensued and a precipitate separated. After stirring for 16 hours at about 20"C, the reaction mixture was washed with water, washed with saturated aqueous sodium bicarbonate solution, washed with water, dried over magnesium sulfate and evaporated under reduced pressure to give a thick oil which crystallized from ethyl ether to give a yellow solid. The yellow solid was washed with cold ethyl/petroleum ether and air-dried to give 15.8 g of 3-(N-chloroacetyl-N-2,6-dimethyl- phenylamino)-5-methyl-gamma-butyrolactone, m.p. 128-131 0C.

Example 3 - Wettable Powder Formulation A 50% wt. wettable powder formulation was prepared by mixing 52.1 parts by weight of 3-(N-chloroacetyl-N-2,6-dimethylphenylamino)-gamma-butyrolactone (96% purity), 42.9 parts by weight of attapulgite clay and 5 parts by weight of a blend of anionic surfactants, lignosulfonates and sodium stearate.

Example 4 - Aqueous Flowable Formulation A 0.41 kg/liter flowable formulation was prepared by mixing 44.22 parts by weight of 3-(N-chloroacetyl-N-2,6-dimethylphenylamino)-gamma-butyrolactone (96% purity), 43.43 parts by weight water, 1.42 parts by weight of a polyvinyl acetate/polyvinyl alcohol anti-foaming agent, 9.73 parts by weight of propylene glycol, 0.20 parts by weight of a polysaccharide thickener and 1 part by weight of a nonionic surfactant.

Example 5 -- Preventative Grape Downy Mildew Control Compounds A and B, and several structurally related compounds, were tested for the control of the grape downy mildew organism Plasmora viticola. Detached leaves, between 70 and 85 mm in diameter, of 7-week-old Vitis vinifera cultivar Emperor grape seedlings were used as hosts. The leaves were sprayed with a solution of the test compound in acetone. The sprayed leaves were dried, inoculated with a spore suspension of the organism, placed in a humid environment chamber and incubated at 18 - 220C and about 100% relative humidity. Seven to nine days after inoculation, the amount of disease control was determined. The percent disease control provided by a given test compound was based on the percent disease reduction relative to untreated check plants. The test compounds, test concentrations and results are tabulated in Table I.

- Example 6 - Eradicant Grape Downy Mildew Control Compounds A and B and several structurally related compounds were tested for the eradicant control of the grape downy mildew organism Plasmopara viticola.

Detached leaves of between 70 and 85-mm diameter of 7-week-old Vitis vinifera cultivar Emperor grape seedlings were used as hosts. The leaves were inoculated with the organism and placed in an environment chamber and incubated at 18--22"C and at about 100% relative humidity for 2 days. The leaves were then sprayed with a solution of the test compound in acetone. The sprayed leaves were then maintained at 18--220C and at about 100% relative humidity. Seven to nine days after inoculation, the amount of disease control was determined. The percent disease control provided by a given test compound was based on the percent disease reduction relative to nontreated check plants. The test compounds, the test concentrations and the results are tabulated in Table I.

TABLE I Grape Downy Mildew Control with Compounds of the Formula

Grape Downy Mildew Control Preventive Eradicative No. Rx R R Y % (ppm) ED50/90* % (ppm) ED50/90 A 2,6-(CH3)2 CH2Cl H O 97 (6.4) 1.2/4.4 99 (6.4) 1/3 99 (100) B 2,6-(CH3)2 CH2Cl CH3 O 80 (100) 8/100 95 (40) 7/28 1 3,4-Cl2 CH2CH3 H O 0 (100) - 5 (40) 2 2,6-(CH3)2 3,4-Cl2-# H O - - 29 (100) 3 2-CH3O CH2Cl H O 0 (100) - 12 (100) 4 2,6-(CH3)2 CH2Cl H NCH3 - - 3 (100) 5 H CH2Cl H O - - 0 (100) 6 2,6-(C2H5)2 CH2Cl H O 0 (100) - 39 (100) 7 2-iC3H7 CH2Cl H O 3 (100) - 17 (16) 8 2-C2H5 CH2Cl H O 0 (100) - 0 (100) 9 2,6-Cl2 CH2Cl H O 0 (100) - 95 (100) 35/70 10 3,4-Cl2 CH2Cl H O 89 (100) 66/107 39 (100) 11 3,5-Cl2 CH2Cl H O 45 (100) - 54 (100) 12 2,6-(C2H5)2 CH2Cl CH3 O - - 87 (100) 38/100 13 2-CH3-6-C2H5 CH2Cl H O 0 (100) - 87 (100) 14 2-CH3-6-C2H5 CH2Cl CH3 O - - 29 (100) 15 2,6-(CH3)2 CH2Br H O - - 54 (100) 84/ * ED50 (ppm of applied spray for 50% control) ED90 (ppm of applied spray for 90% control) # phenyl TABLE I (Continued) Grape Downly Mildew Control Preventive Eradicative No. Rx R R Y % (ppm) ED50/90 % (ppm) ED50/90 16 2,6-(CH3O)2 CH2Cl H O - - 67 (100) 17 2,6-(CH3)2 CH2CH2Cl H O - - 50 (100) 117/18 2,6-(CH3)2 CH2Cl H NCH(CH3)2 15 (100) - 37 (100) 19 2,6-(CH3)2 CCl CCl2 H O - - 15 (100) 20 2,6-(CH3)2 CH2Cl H NCH2CH=CH2 - - 0 (100) 21 2,6-(CH3)2 CH2Cl H NH - - 0 (100) 22 2,6-(CH3)2 CH2Cl H N(3-CH2-4-CI)# - - 32 (100) 23 2,6-(CH3)2 4-Cl-# H NCH3 - - 0 (100) 24 2,4,6-(CH3)3 CH2Cl H O - - 0 (100) 25 2-CH3-6-t-C4H9 CH2Cl H O - - 0 (100) 26 3,4-(CH3)2 CH2Cl H O 12 (100) - 87 (100) 27 Open-chain ester** 78 (100) 32/152 96 (100) 5/10 28 Captafol*** 84 (40) 22/54 74 (200) 100/310 29 Bordeaux Mixture (water used as solvent) 100 (40) 100 (40) 2/13 5/19 92 (16) 86 (16) ** N-(1-methoxycarbonylethyl-N-alpha-chloracetyl-2,6-dimethylaniline (U.K. Patent 1,445,387) *** cis-N-(1,1,2,2-tetrachloroethylthio)-4-cyclohexene-1,2-dicarboximide Example 7 - Preventive Grape Downy Mildew Control A test was conducted to compare the effectiveness of 3-(N-chloracetyl-N-2,6dimethylphenylamino)-gamma-butyrolactone and two commercial fungicides for the control of grape downly mildew Plasmopara viticola. The commercial fungicides used were Folpet [N-(trichloromethylthio)phthalimide] and Captafol [cis-N (1,1,2,2-tetrachlorethylthio)-4-cyclohexene-1,2-dicarboximide. The test was conducted as follows: Detached leaves of 3-month-old Cabernet Sauvignon grape plants were used as hosts. Four leaves were used in each test. The leaves were sprayed with a solution of the test compound in a 1% acetone/99% water solution containing 40 ppm of a nonionic surfactant. The sprayed leaves were dried and inoculated with 25 droplets of a sporangial suspension of the organism (400,000 conidia/milliliter water). After inoculation, the leaves were kept in a high-humidity chamber. After 10 days, the amount of disease control was determined. The percent disease control provided by the test compound was based on the percent disease reduction relative to untreated check leaves. The test compound, the test concentration and the percent control are tabulated in Table II.

TABLE II Preventive Grape Downy Mildew Control Percent Control Test Compound 40 ppm 16 ppm 6.4 ppm Compound A 100 100 100 Folpet 97.7 98.8 80.1 Captafol 96.5 98.8 95.3 Example 8 -- Fermentation Test An in-vitro test was carried out to determine the influence of 3-(N chloroacetyl-N-2,6-dimethylphenylamino)-gamma-butyrolactone (Compound A) on yeasts responsible for the alcoholic fermentation of grapes. The test was conducted as follows: Erlenmeyer flasks (500 cc) were filled with 200 cc of grape juice (density 1.07 gm/cc) extracted from bunches of Madeleine Angevine grapes. The test compound was added to the grape juice and the extent of fermentation determined by measuring the cumulative loss of weight due to carbon dioxide escape. For comparison, the test was conducted with an untreated check and a commercial fungicide. The concentration of test compound and the results for the first 8 days of fermentation are tabulated in Table III.

TABLE III Fermentation Test Cumulative loss of weight (in grams) due to CO2 escape after Product Conc. added ppm 1 day 2 days 3 days 4 days 7 days 8 days Comp. A 1 0.9 5.0 10.5 11.3 14.2 14.5 2 0.8 5.2 10.4 11.1 13.4 13.7 A 1.0 5.2 10.4 11.1 13.1 13.3 8 1.0 5.4 11.0 11.8 14.5 15.2 Commercial 1 0.4 0.5 2.8 3.6 8.9 10.1 Fungicide 2 0.2 0.4 1.3 1.8 4.7 5.6 4 0.4 0.4 0.7 0.8 2.1 3.1 8 0.3 0.4 0.7 0.7 1.2 1.5 None - 0.9 5.4 11.1 11.6 14.2 14.5 Example 9 -- Eradicant Downy Mildew Control 3-(N-chloroacetyl-N-2,6-dimethylphenylamino)-gamma-butyrolactone (Compound A) and several commercial fungicides were tested for the eradicant control of downy mildew Plasmopara viticola on grape leaves. The commercial fungicides employed were: Captafol - cis-N-( l, l ,2,2-tetrachloroethylthio)-4-cyclohexane- 1 2-di- carboximide Pentinacetate -- triphenyltin acetate Chlorothalonil - 2,4,5,6-tetrachloroisophthalonitrile Cupric sulfate Detached leaves of Carignane and Emperor grape plants were used as hosts.

The leaves were inoculated with the organism and placed in an environment chamber and incubated at 18--22"C and at about 100% relative humidity for 1 to 3 days (1 to 2 days for Emperor leaves, 3 days for Carignane leaves). The leaves were then sprayed with a solution of the test compound in acetone. The sprayed leaves were then maintained at 18-220C and at about 100% relative humidity. Eight to nine days after inoculation, the amount of disease control was determined. The percent disease control provided by a given test compound was based on the percent disease reduction relative to nontreated check leaves. The test compound, the grape leaf variety, the time of treatment with the test compound (days after inoculation) and the results of ED50 (ppm of applied spray for 50% control) and ED, (ppm of applied spray for 90/O control) are tabulated in Table IV.

TABLE IV Eradicant Grape Downy Mildew Control Eradication EDso/EDgo Emperor Leaves Carignane Leaves Test Compound 1 day 2 days 3 days Compound A 9.3/58 27/99 20.7/113 Captafol 55/145 64/168 206/670 Fentinacetate 47/171 88 /219 254/562 Chlorothalonil 128/293 410/1000+ 313/992 Cupric sulfate* 118/289 204/445 380/610 * Water used as a solvent.

Example 10 -- Eradicant Downy Mildew Control A wettable powder formulation of 3-(N-chloroacetyl-N-2,6 dimethylphenylamino)-gamma-butyrolactone in attapulgite clay was tested for the eradicant control of grape downy mildew on grape leaves. Three-month-old single bud Cabernet Sauvignon cuttings (cultivated in gravel) containing 6 to 10 leaves were used as hosts. The undersides of the leaves were sprayed with a sporangial suspension of Plasmora viticola containing 510,000 conida per milliliter of water.

The inoculated cuttings were placed into a misting chamber. An aqueous suspension containing 62.5 ppm of test compound was sprayed on the cuttings at a rate of approximately 3.5 ml per 100 cm2 of leaves at four different dates after the date of inoculation. Ten to 11 days after the inoculation, the amount of disease control was determined. The percent disease control provided by the test compound was based on the percent disease reduction relative to untreated check cuttings. The results are tabulated in Table V.

TABLE V Eradicant Grape Downy Mildew Control Interval between inoculation Conc. of and fungicide treatment Fungicide % Leaf Surface % Disease (in days) (ppm) Infected Control 1 0 21 1 62.5 0.51 97.6 2 0 14.3 2 62.5 0.55 96.2 3 0 27.14 3 61.5 4.15 84.7 5 0 29.84 5 62.5 2.5 91.6 Example ii - Residual Preventive Grape Downy Mildew Control A wettable powder formulation of 3-(N-chloroacetyl-N-2,6-dimethyl phenylamino)-gamma-butyrolactone in attapulgite clay was tested for residual preventive downy mildew control on grape leaves. Three-month-old single-bud Cabernet Sauvignon cuttings (cultivated in gravel), containing 5 to 8 leaves, were used as hosts. The cuttings were sprayed with an aqueous suspension containing 160 ppm of the test compound at a rate of approximately 4 mV100 cm2 of leaves.

The cuttings were then placed in a humid chamber at 90 to 95% relative humidity.

Three days after fungicide treatment, the undersides of the leaves were sprayed with a sporangial suspension of Plasmopara viticola. The inoculated cuttings were put into a misting chamber. Eight to 10 days after the inoculation, the amount of disease control was determined. The percent disease control provided by the test compound was based on the percent disease reduction relative to untreated check cuttings. The results are tabulated in Table VI TABLE VI Residual Preventive Grape Downy Mildew Control Interval between inoculation Conc. of and fungicide treatment Fungicide % Leaf Surface % Disease (in days) (ppm) Infected Control 3 0 12.81 3 160 0.03 99.8 Example 12 - Contrnl of Foliar Downy Mildew Infection bv Root Absorption A 50% wettable powder formulation of 3-(N-chloroacetyl-N-2,6 dimethylphenylamino)-gamma-butyrolactone in attapulgite clay was tested for the control of foliar grape downy mildew infection by root absorption. Three-month old single-bud Cabernet Sauvignon cuttings (cultivated in gravel), containing 9 to 12 leaves, were used as hosts. The roots of the cuttings were dipped for 6 hours in an aqueous suspension containing 50 ppm of the test compound. The cuttings were then replanted in gravel and put into a misting chamber. At four different times after root treatment, the leaf undersides were sprayed with a sporangial suspension of Plasmopora viticola. The inoculated cuttings were placed into the misting chamber to stimulate disease development. Ten to 12 days after inoculation, the amount of disease control was determined. The percent disease control provided by the test compound was based on the percent disease reduction relative to untreated check cuttings. The results are tabulated in Table VII.

TABLE VII Control of Grape Downy Mildew by Root Absorption Interval between root treatment Conc. of and inoculation Fungicide SG Leaf Surface % Disease (in days) (ppm) Infected Control 1 0 10.92 1 50 6.26 33.5 5 0 17.51 5 50 0.32 98 9 0 10.11 - 9 160 0.19 99 16 0 39.35 16 160 22.43 43 Example 13 - Control of Lettu

TABLE VIII Lettuce Downy Mildew Control Total No.

Rates Seedlings % Dead Fungicide g active/hi per flat Seedlings Control Test Compound 25 689 5.9 75.8 Test Compound 50 780 1.1 90.6 Test Compound 100 780 2.3 95.5 Captafol 160 614 3.6 85.2 Maneb* 160 422 14.5 40.6 Untreated uncon taminated check - 363 1.9 Untreated con taminated check - 427 24.4 * Manganous ethylene bisdithiocarbamate.

Example 14 -- Preventive and Curative Control of Cabbage Downy Mildew A 50% wettable powder formulation of 3-(N-chloroacetyl-N-2,6-dimethyl phenylamino)-gamma-butyrolactone in attapulgite clay was tested for the control of the cabbage downy mildew organism, Peronospora parasitica ssp. brassicae.

Preventive Control Cabbage seeds (cultivar Milan hatif d'Aubervilliers were planted in plastic flats containing a soil mixture of 3 parts compost and 1 part sand. The seeded flats were maintained in a high-humidity greenhouse environment. Seven days after planting, 3 flats of cabbage seedlings were sprayed until runoff with an aqueous suspension of the test compound at various concentrations. Two days after fungicide application, the flats of cabbage seedlings were sprayed with an aqueous suspension of the conidia (about 300,000 per ml) of the organism. Eleven days after inoculation, amount of disease control was determined by counting the number of diseased seedlings at the 1-leaf stage covered with a white mycelium. The results for flats treated with the test compound, a commercial standard and check flats are tabulated in Table IX.

Curative Control Cabbage seeds (cultivar Milan hatif d'Aubervilliers) were planted in plastic flats containing a soil mixture of 3 parts compost and l part sand. The seeded flats were maintained in a high-humidity environment. Nine days after planting, 3 flats of cabbage seedlings were sprayed with an aqueous suspension of the conidia (about 300,000 per ml) of the organism. Four days after inoculation, the flats were sprayed until runoff with an aqueous suspension of the test compound at various concentrations. Seven days after fungicide application, the amount of disease control was determined by counting the number of diseased seedlings at the 1-leaf stage covered with white mycelium. The results for the flats treated with the test compound, a commercial standard and check flats are tabulated in Table IX.

TABLE IX Control of Cabbage Downy Mildew Preventive Rates a.i. Total No. of % Diseased Fungicide g/hl Seedlings Seedlings Control* Compound A 80 231 1.5 98.5 Compound A 40 138 2.2 97.7 Compound A 20 171 1.8 98.2 Captafol 160 161 59.6 38.9 None/inoculated 175 97.6 None/not inoculated - 177 1.7 Curative Rates a.i. Total No. of % Diseased Fungicide g/hl Seedlings Seedlings Control* Compound A 80 155 0.6 99.4 Compound A 40 203 1.0 99.0 Compound A 20 165 1,8 98.2 Captafol 160 148 65.5 32.9 None/inoculated - - - - None/not inoculated - - - * Disease reduction relative to check flat which was not treated with fungicide Example 15 - Foliar Treatment of Cucumber Downy Mildew Compound A was tested by a foliar spray application for the control of the cucumber downy mildew organism Pseudoperonospora cubensis.

A 3-week old cucumber plant (cultivar Marketeer) was sprayed with a solution of the test compound in a 1% acetone/99% water suspension containing 40 ppm of a nonionic surfactant. Four leaves were detached from the plant, dried and inoculated by spraying with a spore suspension of the organism. After inoculation, the leaves were kept at 2O250C in a high-humidity chamber. After 6 days, the amount of disease infection was determined. The percent disease control provided by the test compound was based on the percent disease reduction relative to untreated check leaves. The test compound, the test concentration and the percent control are tabulated in Table X.

TABLE X Foliar Spray Control of Cucumber Downy Mildew Test Compound Conc. (ppm) % Control Compound A 100 100 Compound A 40 88 Compound A 16 63 Maneb 100 98.3 Maneb 40 90 Maneb 16 80 Example 16 - Control of Snapdragon Crown and Root Rot Compound A was tested to determine its activity against the crown and root rot organism Phytophthora cryptogea on snapdragon plants (cultivar Antirrhinum).

For comparison, Captafol and Mancozeb were included in the test.

Soil Drench Four pots filled with young plants were transplanted into 13-cm soil infected with the organism. Forty ml of a l00-ppm aqueous solution of the test compound was poured in the pots. The plants were then maintained in a greenhouse for disease development. Five days after treatment, the plants were rated for leaf necrosis and wilt, and crown rot. The percent disease control provided by the test compound was based on disease reduction related to non-treated check plants. The results are tabulated in Table XI.

Foliar Spray Young plants were transplanted into 13-cm pots (4) filled with soil infected with the organism. The soil was covered with a plastic covering and the plant foliage was sprayed to runoff with 100 ppm aqueous suspension of the test compound. The plants were then placed in a greenhouse for disease development.

Five days after treatment, the plants were rated for leaf necrosis and wilt, and crown rot. The percent disease control provided by the test compound was based on disease reduction related to non-treated check plants. The results are tabulated in Table XI.

TABLE XI Snapdragon Crown and Root Rot Control % Control Compound Soil Drench Foliar Spray A 100 97 Captafol 0 0 Mancozeb* 0 0 * ] [1 2-ethanediylbis(carbamodithioato)](2-) manganese mixture with {[1,2-ethanediylbis(carbamodithioato)](2-)}zinc Example 17 -- Systemic Foliar Treatment for Safflower Crown and Root Rot Control Compound A was tested to determine its systemic activity in foliar applications against the crown and root rot organism Phytophthora cryptogea.

Two-week-old safflower seedlings were used as hosts. Pots containing the seedlings were sprayed with an aqueous solution of the test compound at various test concentrations. One day after treatment a spawn of the organism was poured on the soil surface in the pots. The spawn was prepared by cultivating the organism in a mixture of oat flakes, potato dextrose and soil. The inoculated seedlings were then maintained in a greenhouse at 2O-25CC day and lS-200C night temperature.

Three to four weeks after inoculation, the plant roots and crown were rated for disease. The percent disease control provided by the test compound was based on percent disease reduction relative to non-treated check plants. The test concentration and the percent disease control are tabulated in Table XII.

TABLE XII Safflower Crown and Root Rot Control by Foliar Spray Compound Conc. ppm % Control

Compound A 100 100 40 97 o /ccH2cl 16 92 C113 \~/ \ 100 100 10 CHCo2CH3 100 10 Coif3 CH3 40 0 CH3 16 0 Standard** (5-ethoxy-3-trichloro 100 61 methyl-i, 2,4-thiadiazole) 40 1 16 0 ** U.S. Patent Nos. 3,260,588 and 3,260,725.

Example 18 - Systemic Soil Drench Treatment for Safflower Crown and Root Rot Control Compound A was tested to determine its systemic activity in soil-drench applications against the safflower crown and root rot organisms, Phytophthora cryptogea and P. parasitica.

Two-week-old safflower seedlings were used as hosts. Pots containing the seedlings were drenched with an aqueous suspension of the test compound at various test concentrations (four pots per concentration level). One day after treatment a spawn of the organism was poured on the soil surface in the pots. The spawn was prepared by cultivating the organism in a mixture of oat flakes, potato dextrose and soil. The inoculated seedlings were then maintained in a greenhouse at 2W25 C day and 15--200C night temperature. Three to four weeks after inoculation, the plant roots and crown were rated for disease. The percent disease control provided by the test compound was based on percent disease reduction relative to non-treated check plants. The test concentrations and the percent disease control are tabulated in Table XIII.

TABLE XIII Safflower Crown and Root Rot Control by Soil Drench SO Control Conc.

Compound ppm P. Cryptogea P. Parasitica Compound A 100* 100 100 40 97 99 16 92 94 Standard** (5-ethoxy-3- 100 78 80 trichloromethyl-1,2,4 thiadiazole) 40 12 21 16 0 0 * 100 ppm= 50 micrograms /cm2 4.46 Ibs,'acre ** U.S. Patents 3,260,588 and 3,260,725 Example 19 -- Systemic Soil Drench Treatment for Tobacco Crown and Root Rot Control Compound A was tested to determine its systemic activity in soil-drench applications against the crown and root rot organisms Phytophthora parasitica and P. cryptogea.

Ten-week-old tobacco seedlings (cultivar Glurk) were used as hosts. Pots containing the seedlings were drenched with an aqueous solution of the test compound at various test concentrations (4 pots per concentration level). One day after treatment a spawn of the organism was poured on the soil surface in the pots.

The spawn was prepared by cultivating the organism in a mixture of oat flakes, potato dextrose and soil. The inoculated seedlings were then maintained in a greenhouse at 20-250C day and 15--20"C night temperature. Three to four weeks after inoculation, the plant roots and crown were rated for disease. The percent disease control provided by the test compound was based on percent disease reduction relative to non-treated check plants. The test concentration and the percent disease control are tabulated in Table XIV.

TABLE XIV Tobacco Crown and Root Rot Control by Soil Drench % Control Conc.

Compound ppm P. Cryptogea P. Parasitica Compound A 100* 100 100 Compound A 40 99.8 99.8 Compound A 16 96 96 Standard** (5-ethoxy-3- 100 80 52 trichloromethyl-1,2,4 thiadiazole) 40 48 30 16 9 0 * 100 ppm = 50 micrograms/cm2 = 4.46 1bs /acre ** U.S. Patents 3,260,588 and 3,260,725 Example 20 -- Control of Phytophthora Rot in Sweet Peppers A 50% wettable powder formulation of 3-(N-chloroacetyl-N-2,6-dimethylphenylamino)-gamma-butyrolactone in attapulgite clay was tested for the control of Phytophthora rot in sweet peppers caused by the soil-inhabiting Phytophthora capsici organism.

Sweet pepper seedlings (cultivar Doux de Valence) at the 4-leaf stage were planted in pots filled with a sterilized mixed soil of 1/2 compost and 1/2 sandy soil.

The pots were then inoculated with the organism by sprea ing a bed of oats grain (contaminated with the Phytophthora capsici organism) on the soil surface and covering the bed with a I-cm depth of sterilized soil. The sweet pepper seedlings were then sprayed to runoff with an aqueous suspension of the test compound at various test concentrations (12 pots per concentration level). The amount of disease control was determined by counting the number of dead plants. The percent disease control provided by the test compound was based on the percent disease reduction relative to untreated check seedlings. The results are tabulated in Table XV.

TABLE XV Control of Pepper Phytophthora Rot Conc. of Fungicide % of Alive 70 Lead Surface g/hl Seedlings C < C Control Damaged 100 50 25 0 200 100 100 1.3 400 100 100 1.63 0 33.3 - 0

Claims (11)

WHAT WE CLAIM IS:

1. A method of controlling downy mildew fungal infection on plants caused by Peronsporaceae fungi or crown and root rot diseases caused by soil-inhabiting Phytophthora fungi, which comprises applying to said fungi or their habitats an effective amount of a compound of the general formula:

wherein R is hydrogen or methyl.

2. A method of preventing or eradicating downy mildew fungal infection on plants caused by Peronsporaceae fungi, which comprises applying to plants liable to or having said fungal infection an effective amount of a compound of the general formula defined in Claim 1.

3. A method according to Claim 2, wherein the plants are grape plants.

4. A method according to Claim 2, wherein the plants are grape plants which produce grapes for fermentation.

5. A method according to Claim 2, wherein the plants are lettuces or cabbages.

6. A method of preventing or eradicating crown or root rot diseases caused by soil-inhabiting Phytophthora fungi, which comprises applying to the growth medium of plants or plant hosts of Phytophthora fungi an effective amount of a compound of the general formula defined in Claim 1.

7. A method according to Claim 6, wherein the plant or plant host is tobacco, snapdragon, safflower or pepper.

8. A method according to any preceding claim, wherein R is hydrogen.

9. A method in accordance with Claim 2 of preventing or eradicating downy mildew fungal infection on plants caused by Peronsporaceae fungi, substantially as described in any one of the foregoing Examples 5 to 15.

10. A method in accordance with Claim 6 of preventing or eradicating crown or root rot diseases caused by soil-inhabiting Phytophthora fungi, substantially as described in any one of the foregoing Examples 16 to 20.

11. For use in preventing or eradicating grape downy mildew fungal infection or preventing or eradicating crown or root rot diseases, a fungicidal composition comprising as the essential active ingredient a compound of the general formula defined in Claim I in association with an inert diluent or carrier therefor.