CA1108076A - Agricultural production of ergot - Google Patents

Abstract

Abstract of the Disclosure The production of ergot in gramineous plants is increased when the plants are treated with a chemical gametocide to induce sterility prior to infection with ergot spores.

Description

The Disclos_re This invention relates to methods for producing ergot using chemical gametocides.
Ergot, the sclerotium of the parasitic fungus Clavice~s ~ur~urea, has historically been an insidious pest in the cultivation of cereal crops. However, in recent years the development of many useful therapeutic dru~s from ergot alkaloids has made its production not only desirable but also commercially attractive. While ergo~ can be grown in vitro, most of the ergot used in drug production comes from its agricultural cultivation, primarily in rye. Since ergot yields from such cultivation are usually about 50 to 200 kg./ha and the total alkaloid content of this ergot usually ranges between only 0.1 and 0.3 percent, methods for ~-5 enhancing the yield of ergot or the quantity of ergot alkaloids produced in each plant would be particularly desirable.
The ergot fungus goes through a three-phase life cycle. In the first stage, fungal ascospores carried by the wind or by insects attack the ovaries of gramineous plants, which when infected produce "honeydew", a liqu~d exudate containing ergot conidiospores (conidia). The con-idia are then transferred usually by insects to other ovaries in the same or a different plant or from wild plants to cultivated grain crops. From the infection of the conidia, the fungus enters a second stage, the production of a dark violet or purplish black mass referred to as the sclerotium.
It is the sclerotium which is harvested and from which 'ne ergot alkaloids are extracted. Finally, the sclerotia 3 which are not harvested fall to the ground, and thereafter germinate to produce the ~ruiting bodies from which the ascospores are discharged.
In the commercial production of ergot, the infec-tion of the ovaries of the host plant is carried out by directly applying to the flowers of the plant a suspension of conidia, usually in water. After development of the sclerotia, harvesting can then be carried out by hand or by conventional mechanical harvesting methods capable of separating the mature grain from the ergot sclerotia.
It has now been found that the agricultural pro-duction of ergot can be improved by applying a chemical gametocide to the gramineous host plant prior to in~ecting the plant with the ergot conidia. The chemical gametocide is generally applied in an amount which will be effective in producing significant sterility in the host plant.
Any chemical gametocide ~- that is, a compound capable of producing thè desired degree of sterillty, with-out causing an adverse phytotoxic response in the host plant -- can be used. In general, those chemical gametocides having little or no fungicidal activity towards the ergot and havlng no signi~icant level o~ adverse growth regulatory activity or phytotoxicity towards th host plant are preferred.
Among the pre~erred classes of compounds are (1) l arylpyrid-

2-cnes of the formula R3- J~ COY

2 ~ N ~ O
ll ~~3 8~

wherein Rl is a group of the formula ~ - 1 or ~

wherein X ls an amino group, a halogen atom, a (Cl-C5)alkyl group, a trifluoromethyl group, a methoxy group, or a nitro group, xl is a halogen atom, a methyl group, a trifluoro-methyl group, or a methoxy group, and n is 0, 1, or 2, R2 is a methyl group or an ethyl group, R3 is a hydrogen atom, a chlorine atom, a methyl group~ or an ethyl group, R4 is a methyl group or an ethyl group, and Y is a bromine atom, a chlorine atom, an amino group, a hydroxy group, or a agronomically-acceptable salt thereof, or a (Cl-C5)alkoxy group, which arè described and claimed in U.SO Patent 3,576,814, granted April 27, 1971, and U.S. Patent 3,761,240, granted September 25, 1973, of Seidel et al; (2) 1-arylpyxid-4-ones of the formula o 8 ~ 1 R ~ ~ COY (II) ~4--8~
wherein R5 is a (Cl-C4)alkyl group, R6 is an unsubstituted phenyl group or a substituted phenyl group having up to 3 substituents, preferably selected ~rom halogen atoms, (Cl-C4)-alkyl groups~ most preferably methyl, (Cl-C4)-alkoxy groups, most preferably methoxy~ trifluoro-methyl groups, and nitro groups, R7 is a hydrogen atom or a (Cl-C4)alkyl group, R8 is a hydrogen atom, a (Cl~C4)alkyl group, or a halogen atom, and yl is an amino group, a (Cl-C4)alkyl- or di(Cl-C4)-alkylamino group, a hydroxy group, or an agronomi-cally-acceptable salt thereof, or a (Cl-C12)-alkoxy group, which are described and claimed in Canadian Patent 1,095,409, of Carlson, granted February 3, 1981; (3) 1-aryl~4-pyridazones of the formula Rll--1 ~ coY3 ~ ~ (III) 10 N ' R

wherein Y3 is a hvdroxy group, or an agronomically~acceptable salt thereof, or a (Cl-C4)alkoxy group, R9 is an unsubstituted phenyl group or a substituted phenyl group having up to 3 substituents, prefer-ably selected from halogen atoms, (Cl-C4)alkyl groups, most preferably methyl~ (Cl-C4)alkoxy ... ... . . .

71~

groups, most preferably methoxy, and trifluoro-methyl groups, R is a (Cl-C4)alkyl group, and Rll is a hydrogen atom, a (Cl~C4)alkyl group, or a halogen atomg which are described and claimed in Canadian Appllcation No. 297,781 of Fujimoto, filed February 27, 1978;
(4) 1-aryl-6-pyrimidones of the formula ~ coY4 R13 o I

wherein Y4 is a hydroxy group, or an agronomically-acceptable salt thereof, a (Cl-C4)alkoxy group, an amino group~ or a (Cl-C4)alkYl or di(cl-c4)alkyl amino group, R12 is an unsubstituted phenyl or naphthyl group or a substituted phenyl group having up to 3 sub-stituents, preferably selected ~rom halogen atoms, (Cl-C4)alkyl groups, most preferably methyl, (Cl-C4)alkoxy groups, most pre~erably methoxy, trifluoromethyl groups, and nitro groups, R 3 is a hydrogen atom~ a (C1-C4)alkyl group, an aryl group having up to 10 carbon atoms, or a~
aralkyl group having up to 10 carbon atoms, and R14 is a (Cl-C4)alkyl group, an aryl group having up to 10 carbon atoms~ or an aralkyl group having ~.

up to 10 carbon atoms~
which are described and claimed in U.S. Patent No. 4,147,528 of McNulty et al, granted April 3, 1979; and ~5) l-arylpyrid-2-ones of the formula the formula R17~ coY5 11 (V) ~ N ~

R16 ~ !

wherein Y5 is a hydroxy group, or an agronomically-acceptable salt thereof, or a (Cl-C4)alkoxy group, R15 is a (Cl-C4)alkyl group, R16 is an unsubstituted phenyl or naphthyl group ~ .
or a substituted phenyl group having up to 2 substituents, preferably selected f.rom halogen atoms, (Cl-C4)alkyl groups, most preferably methyl, (Cl-C4)alkoxy groups, most preferably methoxy, trifluoromethyl groups, and nitro groups, R 7 is a hydrogen atom, a (Cl-C4)alkyl group, or a halogen atom, and R is a hydrogen atom or a (Cl-C4)alkyl group, which are described and claimed in Canadian Patent 1,085,857 20 of Carlson, granted September 16, 1980.
The compounds of formulas I, II, IIX and V are preferred. Typical compounds within the scope of formulas I ~o V include:

, .~
.

N-(4-chlorophenyl)~3-carboxy-4,6-dimethylpyrid-2-one N-(4-bromophenyl)-3-carboxy-4,6-dimethylpyrid-2-one N-(4-tri~luoromethylphenyl)-3-carboxy-4,6-dimethylpyrid-2-one N-(3-chlorophenyl) 3-carboxy-4,6-dimethylpyrid-2-one N-(3,4-dichlorophenyl)-3-carboxy-4,6-dimethylpyrid-2-one N-(4-chlorona~hthy~-3-carboxy-4,6-dimethylpyrid-2-one N-t4-chlorophenyl)-3-carboxy-2,6-dimethylpyrid-4-one N-(4-fluorophenyl)-3-carboxy-2,6-dimethylpyrid-4-one N-phenyl-3-carboxy-2,6-dimethylpyrid-4-one N-(4-bromophenyl-3-carboxy-2,6-dimethylpyrid-4-one N-(3-chlorophenyl)-3-carboxy-2,6-dimethylpyrid-4-one N-(4-tri~luoromethylphenyl)-3-carboxy-2,6-dimethylpyrid-4-one N-phenyl-5-bromo-3-carboxy-2,6-dimethylpyrid-4-one l-phenyl-1,4-dihydro-4-oxo-6-methylpyridazinone-3-carboxylic acid 1-(4-chlorophenyl)-1,4-dihydro-4-oxo 6-methylpyridazinone-3-car~oxylic acid 1-(4-bromophenyl)-1,4-dihydro-4-oxo-6-methylpyridazinone-3-carboxylic acid 1-(3-chlorophenyl)-1,4-dihydro-4-oxo-6-methylpyridazinone-3-carboxylic acid l-t4-tri~luoromethylphenyl)-1,4-dihydro-4-oxo-6-methylpyri-dazinone-3-carboxylic acid Ekhyl l-phenyl-1,4-dihydro-4-oxo-6-methylpyridazi.none-3-carboxylate Ethyl 1-(4-chlorophenyl)-1,4-dihydro-4-oxo-6-methylpyrida-zinone-3-carboxylate 1-(4-chlorophenyl)-1,6-dihydro-4-methyl-6~oxopyrimidine-5-carboxylic acid 1-(3,4-dichlorophenyl~-1,6-dihydro-4-methyl-6-oxopyrimidine-5-carboxylic acid 1-(4-chlorophenyl)-1,6-dihydro 2,4-dimethyl-6-oxopyrimidine-5-carboxylic acid 1-(3,4-dichlorophenyl)-1,6~dihydro-2,4-dimethyl-6~oxopyrimi-dine-5~carboxylic acid 1-(4-chlorophenyl)-5-carboxy 4,6-dimethylpyrid-2-one 1-(4-bromophenyl)-5-carboxy-4,6-dimethylpyrid-2-one 1-(3,4-dichlorophenyl)-5-carboxy-4,6-dimethylpyrid-2-one Ethyl 1-(4-bromophenyl)-4,6 dimethylpyrid~2-one-5-carboxylate Ethyl 1-(4-chlorophenyl)-4,6-dimethylpyrid-2-one~5-carboxylate ~ Other chemical gametocides which can be used in the pra.ctice of the present invention include gibberellins, auxins, morphactin~s~ maleic hydrazide, sodium 2,3-dichloroisobutyrate, naphthalene acetic acid and derivatives, 2,3,5-triiodobenzoic acid, 2-chloroethylphosphoric acid, 3-(4-chlorophenyl)-6-methoxy-5-triazine-2,4-(lH,3H)-dione, and the like. Mixtures of these chemical gametocides can also be employed.
The chemical gametocides can be applied to the ergot host plant ln any amount which will produce significant sterility in the plant. Preferably, about 60~ or more male or ~emale sterility, or both, will be most advantageous.
Generally, the desired level of ste.rility will be obtained by applying the chemical gametocide to the host plant at a rate of about 1/32 to about 20 pounds per acre, and prefer-ably about 1/16 to about 8 pounds per acre. The rate of application will vary depending on the host plant being treated, the chemical gametocide being applied, the time of treatment, and related factors.
A preferred method of applying the chemical game~
tocide is by foliar application. When this method is employed, sterility is generally most e~fectively induced when the gametocide is applied between flower initiation and meiosis.
The chemical gametocide can also be applied as a seed treat-ment by soaking the seed in a liquid formulation containing the gametocide or by coating the seed with the compound. In seed treatment applications, the g~metocide will generally 7~

be applied at a rate of about 1/4 to about 10 pounds per hundred~eight of seed.
A wide variety of gramineous plants can be employed as the host plant. Among the preferred plants are the cereal ~rains, such as wheat,includin~ durum3 rye, triti-cale, and the liXe. One of the advantages of the present inven~ion is that wheat, not normally susceptible to heavy infestation by ergot using conventional methods, is quite suitable for producing good yields of ergot by the method of the present inventionO Not only does wheat have a high inherent capacity for ergot in~ection, it also resists lodgin~ better than rye, the conventional host plant, thereby facilitating harvesting, and produces heavier, more compact ergot sclerotia. Generally, the chemical gametocide first will be applied to the host plant, preferably prior to flowering, and the host plant will be inoculated with ergot spores by any conventional procedure~ subsequently, prefer-ably at the time of or soon after flower opening. After the ergot has been allowed to mature, it can be harvested by conventional procedures.
The chemical gametocide can be applied to the plants to be treated either by itsel or, as is generally done, as a component in an agricultural composition or formulation which also comprises an agronomically acceptable carrier. By "agronomically-acceptable carrier" is meant any substance which can be used to dissolve, disperse, or diffuse the chemical gametocide in the composition, without impairing its effectiveness and which by itself has no significant detrimental effect on the soil, equipment, crops 3 or agronomic environment. Mixtures of chemical gametocides --10~

7~

may also be used in any of these formulations. The compo-3itions of the invention can be either solid or liquid formulations or solutions. For example, the chemical gametocides can be formulated as wettable powders, emul-sifiable concentrates, dusts, granular formulations, aero-sols, or flowable emulsion concentrates. In such formula-tions, ~he active compounds are extended with a liquid or solid carrier and, when desired suitable surf`actants are incorporated.
It is usually desirable, particularly in foliar applications, to include adjuvants, such as wetting agents, spreading agents, dispersing agents, stickers, adhesives, and the like, in accordance with agricultural practices.
Examples of adjuvants which are commonly used in the art can be found in the John W. McCutcheon, Inc. publication "Detergents and Emulsiflers Annual."
The chemical gametocides can be dissolved in any appropriate solvent. Examples of solvents which are useful in the practice of this invention include water, alcohols, ketones, aromatic hydrocarbons, halogenated hydrocarbons, dimethylformamide, dioxane, dimethyl sulfoxide, and the like. Mi~tures of these solvents can also be used. The concentration of active ingredient in the solution can vary from about 2~ to about 98% b~ weight with a preferred range being about 20% to about 75%.
For the preparation of emulsifiable concentrates, the active compound can be dissolved in organic solvents, such as benzene, toluene, xylene, methylated naphthalene, corn oila pine oil, o-dichlorobenzene, isophorone~ cyclo-hexanone, methyl oleate, and the like. or in mixtures of 7~

these solven~s, together with an emulsifying agent or surfactant which permits dispersion in water. Suitable emulsifiers include, for example, the ethylene oxide deriv atives of alkylphenols or long-chain alcohols, mercaptans, carboxylic acids, and reactive amines and partially ester-ified polyhydric alcohols. Solvent-soluble sulfates or sul~nates, such as ~he a ~ lme e~h metal salts or ~ne salts o~ alkylbenzenesulfonates and the fatty alcohol sodium sulfates, having surface-active properties can be used as emulsifiers either alone or in con~unction with an ethylene oxide reaction product. Flowable emulsion concentrates are formulated similarly to the emulsifiable concentrates and include, in addition to the above components, water and a stabilizing agent such as a water-soluble cellulose deriva-tlve or a water-soluble salt of a polyacrylic acidO The concentration of the active ingredient in emulsifiable con-centrates of usually about 10% to 50% by weight and in flowable emulsion concentrate this can be as high as about 75~.
Wettable powders sultable for spraying, can be prepared by admixing the chemical gametocide with a finely divided solid, such as clays, inorganic silicates and carbonates, and silicas and incorporating wetting agents, sticking agents, and/or dispersing agents in such mixtures.
The concentration of active ingredients in such formulations is usually in the range of about 20% to 98% by weight, preferably about 40~0 to 75~. A dispersing agent may generally constitute about 0.5% to about 3% by weight of the compo-sition, and a wetting aæent may generally constitu~e from

3 about 0.1% to about 5% by welght o~ the composition.

.. . .

Dusts can be pre~ared by mi~ing the che~ical gametocides with finely divided inert solids which may be organic or inorganic in nature. Materials useful for this ~urpose include, for example, botanical flours~ silica3, silicates, carbonates and clays. One convenient method of preparing a dust is to dilute a wettable powder with a finely divided carrier. Dust concentrates containing about 20~ to 80% of the active ingredient are commonly made and are subsequently diluted to about 1% to 10% by weight use concentration.
Granular formulations can be prepared by impreg-nating a solid such as granular fuller's earth 3 vermiculite, gound corn cobs, seed hulls, including bran or other grain hulls, or similar material. A solution of one or more of the active compounds in a solatile organic solvent can be sprayed or mixed with the granular solid and the solvent then removed by e~aporation. The granular material can have any suitable size, with a preferable size range of 16 to 60 mesh. The active compound will usually comprise about 2 ~0 to 15~o by weight of the granular formulation.
Salts, such as sodium, potassium, lithium, calciu~, magnesiumj ammonium, substituted ammonium salts, and the like, of the chemical gametocides can be formulated and applied as aqueous solutions. The salt will typically comprise about 0 05 to about 50% by weight, preferably about 0.1% to about 10%, of the solution. These compositions can also be fur-ther diluted with water if desired prior to actual appli-^ation. In some applications, the activity o~ these compo~
sitions can be enhanced by incorporating into the composition an adjuvant such as glycerin, methylethylcellulose, hydroxy-ethylcellulose~ polyoxymethylenesorbitan monooleate, poly-propylene glycol, polyacrylic acid, polyethylene sodium malate, polyethylene oxide, or the like. ~he adjuvant will generally comprise about 0.1 to about 5~ by weight, preferably abcut 0.5 to about 2%, of the composition. Such compositions can also optionally include an agronomically-acceptable sur~actant.
The chemical gametocides can be applied as sprays by methods commonly employed, such as conventional hydraulic sprays~ aerial sprays, and dusts. For low-volume appli-cations a solution of the active compound is usually usedO
The dilution and volume of application w~ll usually depend upon such factors as the type of equipment employed, the method o~ application, the area to be treated and the type and stage of development of the crop being treated.
The following example will further illustrate the use of chemical gametocides in the agricultural production of ergot but are not intended to limit the invention in any way.
The following procedures are used ~or evaluating chemical gametocides in agricultural ergot production.
Test plantings of wheat, durum, and triticale are treated with the chemical gametocide during the stem extension period (between stage 8 an~ stage 9 on the Feekes 2~ scale). In a typical treatment, an aqueous formulation of the chemical gametocide sodium N-(4-bromophenyl3 4~6-dime~hyl-pyrid-2-one-5-carboxylate in a carrier volume of 500 liters/ha.
containing a surfactant, such as about 0.03% by weight of I~Triton X-lOO.Ii*The concentration of the chemical gametocide is set to give an application rate of about 1 to 2 kg/ha.

* Octylp~xy polyeth~xy e~ol, a nonlonie surfac~nt. "Tri~?n ? X-100" is a trad~rk of ~Dhm and Haas C~ny.

7~

~he composition is then sprayed onto the test plants using conventional techniques.
~ hen a signi~icant percentage of the flowers of the test plants have opened, the plants are inoculated with ergot spores by spraying a suspension of ergot conidia with an atomizer, preferably directly on the opened flo~ers. If possible, the spraying is carried out during hot, humid weather to insure effective inoculation of the ~lowers with the conidia.
One con~enient method for preparing the conidial suspension used in the inoculation is that described by Campbell, Canad. ~. Botany, 3S (1957). Ergot sclerotia which have been sterilized by shaking for 30 seconds in a 0.1~ aqueous mercuric chloride solution are rinsed in sterile water and cut into small pieces with a sterile knife. The pieces are plated out on an acidified medium~ prepared from 10 g de~trose, 5 g malt extract, 5 g yeast ex~ract, 20 g agar, and 1 liter water. When mycelia have begun to grow out cf the er~ot fragments, they are transferred to slants of potato dextrose agar for sporulation. The spores are then collected and formulated in water to give an optimum concentration of 105 conidia/ml. If desired, 2% sucrose can also be included in the conidial formulation to improve transfer of the ergot spores between plants by insects.
~ithin about three weeks after inoculation, si~nificant growth of ergot sclerotia has occurred. Upon maturity, the sclerotia can be conveniently harvested with a combine and separated from the cereal Orains by hand or by conventional mechanical means. Hi~h yields of ergot are obtained from this treatment, with up to 10 sclerotia per plant varying in weight from about 50 mg to about 650 mg.
It is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (10)

CLAIMS:

1. In a method for the agricultural production of ergot by infecting a gramineous plant with ergot spores and harvesting the mature ergot sclerotia, the improvement which comprises applying to the plant prior to infection with the ergot spores a chemical gametocide in an amount effec-tive to produce significant sterility in the plant.

2. The method of claim 1 wherein the chemical gametocide is applied at a rate of about 1/32 to about 20 pounds per acre.

3. The method of claim 2 wherein the chemical gametocide is a compound of the formula wherein R1 is a group of the formula wherein X is an amino group, a halogen atom, a (C1-C5)alkyl group, a trifluoromethyl group, a methoxy group, or a nitro group, x1 is a halogen atom, a methyl group, a trifluoromethyl group, or a methoxy group, and n is 0, 1, or 2, R2 is a methyl group or an ethyl group, R3 is a hydrogen atom, a chlorine atom, a methyl group, or an ethyl group, R4 is a methyl group or an ethyl group, and Y is a bromine atom, a chlorine atom, an amino group, a hydroxy group, or a agronomically-acceptable salt thereof, or a (C1-C5)alkoxy group.

4. The method of claim 2 wherein the chemical gametocide is a compound of the formula wherein R5 is a (C1-C4)alkyl group, R6 is an unsubstituted phenyl group or a substituted phenyl group having up to 3 substituents selected from halogen atoms, (C1-C4)alkyl groups, (C1-C4)-alkoxy groups, trifluoromethyl groups, and nitro groups, R7 is a hydrogen atom or a (C1-C4)alkyl group, R8 is a hydrogen atom, a (C1-C4)alkyl group, or a halogen atom, and y1 is an amino group, a (C1-C4)alkyl- or di(C1-C4) alkylamino group, a hydroxy group, or an agronomic-ally-acceptable salt thereof, or a (C1-C12)-alkoxy group.

5. The method of claim 2 wherein the chemical gametocide is a compound of the formula wherein Y3 is a hydroxy group, or an agronomically-acceptable salt thereof, or a (C1-C4)alkoxy group, R9 is an unsubstituted phenyl group or a substituted phenyl group having up to 3 substituents selected from halogen atoms, (C1-C4)alkyl groups, (C1-C4)-alkoxy groups, and trifluoromethyl groups, R10 is a (C1-C4)alkyl group, and R11 is a hydrogen atom, a (C1-C4)alkyl group, or a halogen atom,

6. The method of claim 2 wherein the chemical gametocide is a compound of the formula wherein Y5 is a hydroxy group, or an agronomically-acceptable salt thereof, or a (C1-C4)alkoxy group, R15 is a (C1-C4)alkyl group, R16 is an unsubstituted phenyl or naphtyl group or a substituted phenyl group having up to 2 substituents selected from halogen atoms, (C1-C4)alkyl groups, (C1-C4)alkoxy groups, trifluoromethyl groups, and nitro groups, R17 is a hydrogen atom, a (C1-C4)alkyl group, or a halogen atom, and R18 is a hydrogen atom or a (C1-C4)alkyl group.

7. The method of claim 6 wherein R15 is a methyl group, R16 is a halophenyl group, R17 is a hydrogen atom and R18 is a methyl group.

8. The method of claim 8 wherein the chemical gametocide is N-(4-bromophenyl)-4,6-dimethylpyrid-2-one-5-carboxylic acid or an agronomically-acceptable salt thereof.

9. The method of claim 1 wherein the plant is a cereal grain.

10. The method of claim 1 wherein the plant is wheat, durum, rye or triticale.