Note: Descriptions are shown in the official language in which they were submitted.
76
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 5
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)
R7 N R5
R6
~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
R9
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
--5--
... ... . . .
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
R14
~ coY4
R13 o
I
R12
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
R18
R17~ coY5
11 (V)
~ N ~
O I R15
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
-8-
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.
.. . .
76
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-
-13-
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.
14
* 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
76
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.
-16-
