Plant protecting and regulating compositions – Antidotes – Hetero ring containing antidote
Reexamination Certificate
2000-01-18
2001-08-28
Clardy, S. Mark (Department: 1616)
Plant protecting and regulating compositions
Antidotes
Hetero ring containing antidote
Reexamination Certificate
active
06281168
ABSTRACT:
BACKGROUND OF THE INVENTION
One of the most common practices for controlling undesirable plant species is the use of post-emergent selective herbicides. For example, certain compounds which inhibit the enzymes acetohydroxyacid synthase (AHAS), acetyl CoA carboxylase (ACC) and/or 5-hydroxyphenyl-pyruvate-dioxygenase (HPPD) are known herbicides which are effective against certain annual and perennial grass and broadleaf weeds. Unfortunately these herbicides cannot be used in all crops, especially cereal crops such as corn, wheat, barley and rice, because of unacceptable crop tolerance.
Therefore what is needed in the art is a herbicide which is effective against weeds, while protecting the gramineous crop from injury.
It is known, for example from U.S. Pat. No. 4,931,581 and U.S. Pat. No. 5,229,384, that certain benzothiadiazole derivatives have the capability to prevent healthy plants from attack by harmful microorganisms by stimulating the plants'own biological defense system. The term for the plant response on such stimulating agents is systemic acquired resistance (SAR).
SUMMARY OF THE INVENTION
The present invention relates to a a method for protecting cereal crops from injury caused by a herbicidally effective amount of a herbicide, in particular, selected from the group consisting of AHAS-inhibiting, ACCase-inhibiting and HPPD-inhibiting herbicides, which comprises applying to the crop plant, the seed of the crop, or the soil surrounding the crop or crop seed an effective non-phytotoxic antidotal amount of a benzothiazole derivative of formula I
wherein
A represents an alkyl, alkoxy, haloalkoxy, hydroxy, cyano or nitro group or a group of the formula
in which
W represents O or S, and
R represents a hydroxy, thiol, alkoxy, thioalkyl, amino, alkylamino or dialkylamino group; and
X represents CH or N.
This invention also includes a safened herbicidal composition which is effective against weeds, but spares the crop.
The invention furthermore relates to seeds treated with an effective nonphytotoxic antidotal amount a benzothiazole derivative of formula I.
Other objects and advantages of the present invention will be apparent to those skilled in the art from the following description and the appended claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention relates to a method for protecting cereal crops from injury caused by a herbicidally effective amount of herbicides which comprises applying to the crop plant, the seed of the crop, or to the soil surrounding the crop or crop seed an effective non-phytotoxic antidotal amount of a benzothiazole derivative of formula I.
Benzothiazole derivatives which are suitable for use in the present invention are the compounds of formula I. Of these, preferred benzothiazole derivatives are the compounds of formula I wherein X represents N, and A is a —CO—SCH
3
group attached to the 7-position of the benzothiazole moiety or a methyl, cyano, hydroxy or difluoromethoxy group attached to the 4-, 5- or 6-position of the benzothiazole moiety.
The benzothiadiazole derivatives of formula I wherein A
1
represents a methyl, hydroxy, or a C
1-6
fluoroalkoxy group, are especially preferred for safening seeds, especially barley seeds.
As used herein, “Halogen” means a fluorine, chlorine, bromine or iodine atom, and preferably is fluorine, chlorine or bromine.
Generally, when any of the above mentioned moieties comprises an alkyl or alkoxy group, such groups, unless otherwise specified, may be linear or branched and may contain 1 to 6, and preferably 1 to 4, carbon atoms. Examples of such alkyl groups are methyl, ethyl, propyl, isopropyl and butyl. Representative alkoxy groups are those such as methoxy, ethoxy, propoxy, butoxy, and the corresponding branched chain analogs thereof.
Generally, when any of the above mentioned moieties comprises a haloalkoxy group, such groups, unless otherwise specified, may be linear or branched and may contain 1 to 6, and preferably 1 to 4, carbon atoms. Examples of such groups are halomethoxy, haloethoxy, halopropoxy, haloisopropoxy, halobutoxy, haloisobutoxy and halo-tertiary-butoxy groups. Haloalkoxy moieties of any groups within the definitions used herein can contain one or more halogen atoms, preferably fluorine, chlorine or bromine. Haloalkoxy preferably represents mono-, di-, tri- or perfluoroalkoxy groups, especially difluoromethoxy, trifluoromethoxy, pentafluoroethoxy, or 2,2,2-trifluoroethoxy, with difluoromethoxy being especially preferred.
The alkylamino groups are those wherein the alkyl portion contains 1 to 6, and preferably 1 to 4, carbon atoms, and are typically aminomethyl, 2-aminoethyl and the like. Dialkylamino substituents likewise contain 1 to 6, and preferably 1 to 4, carbon atoms in the alkyl portion, as representative variants include dimethylamino, diethylamino and the like for safening seeds, especially barley seeds.
Most preferred are the benzothiazoles selected from the group consisting of 4-difluoromethoxybenzo-1,2,3-thiadiazole, 5-cyanobenzo-1,2,3-thiadiazole, 6-methylbenzo-1,2,3-thiadiazole and 6-hydroxybenzo-1,2,3-thiadiazole.
Another preferred group of benzothiazoles are those compounds of formula I wherein X represents CH, and A is a nitro group attached to the 5-position of the benzothiazole moiety.
The benzothiazoles of formula I are known in the art and may be prepared by the processes described in U.S. Pat. Nos. 4,931,581, and 5,229,384, EP 0 039 795 and British Patent 1177972.
Herbicides which are suitable for use in the present invention include, but are not limited to, AHAS-inhibiting herbicides, ACCase-inhibiting herbicides and HPPD-inhibiting herbicides. Preferred herbicides of the present invention include imidazolinone herbicides such as methyl 6-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-m-toluate and methyl 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)p-toluate (imazamethabenz-methyl), 5-ethyl-2-(4-isopropyl-4-methyl-5oxo-2-imidazolin-2-y)nicotinic acid (imazethapyr), 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-y)nicotinic acid, 5-methoxymethyl-2-(4-isopropyl-4-methyl-5oxo-2-imidazolin-2-y)nicotinic acid and 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl) quinoline-3-carboxylic acid (imazaquin); aryloxyphenoxy propionic acids, such as fenoxaprop including fenoxaprop-P and fenoxaprop-P-ethyl, and clodinafop including clodinafop-propargyl and a mixture of clodinafop-propargyl and cloquintocet; and benzothiopyran derivatives such as (E)-6-{{1-ethyl-5-[(propylsulfonyl)oxy]pyrazol-4-yl}carbonyl}-2,3-dihydro-5-methyl-4-oxo-1,1-dioxide-4H-1-benzothiopyran, 4-(O-methyloxime) and the zinc chelate of (E)-6-{{1-ethyl-5-hydroxypyrazol-4-yl}carbonyl}-2,3-dihydro-5-methyl-4-oxo-1,1-dioxide-4H-1-benzothiopyran, 4-(O-methyloxime).
Although many of these herbicides have been used with success in certain crops, they have been found to be phytotoxic in many cereal crops. Surprisingly, it has been found that by applying certain benzothiazole derivatives of formula I to the crop plant, the seed of the crop, or the soil surrounding the crop or crop seed, the herbicide is safened.
Safening of cereal crops such as corn, wheat, barley and rice from the post emergence application of herbicides may also be effected by allowing said crop plants to grow until the third to early fourth leaf stage and then spraying with an aqueous solution of the safener either alone, or tank-mixed with at least one of the above-described herbicides. The tank mix should contain effective amounts of herbicide and effective amounts of the safener. Although rates will naturally vary with the particular herbicide and crop, typical rates of application for the safener are about 0.05 kg/ha to 2.0 kg/ha.
The application rate of the compound of the herbicides is usually in the range of 0.001 to 2.0 kg/ha, with rates between 0.02-0.5 kg/ha often achieving satisfactory control. In general, the preferred application rate of the herbicides is in the range of 0.01 to 0.5 kg/ha, preferably 0.02-0.3 kg/ha.
The optimal rate for a specific application w
Baltruschat Helmut Siegfried
Nelgen Norbert
Shaner Dale Lester
American Cyanamid Co.
Clardy S. Mark
Maurer Barbara V.
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