WO2006120231A2 - Method of enhancing resistibility of crop plants - Google Patents

Abstract

A method of enhancing resistibility of crop plants against bacterial and/or fungal diseases, which comprises treating the plants or seeds with low rates of 2-{1-[4-(3,5-difluorophenyl)semicarbazono]ethyl}nicotinic acid, common name diflufenzopyr, a method for controlling harmful fungi and bacteria using mixtures of diflufenzopyr and compounds Il and/or III, and also compositions comprising these mixtures.

Description

Method of enhancing resistibility of crop plants

Description

The present invention relates to a method of enhancing resistibility of crop plants against bacterial and/or fungal diseases, which comprises treating the plants, the soil or seeds with low rates of 2-{1-[4-(3,5-difluorophenyl)semicarbazono]ethyl}nicotinic acid, common name diflufenzopyr (DFFP) of formula I

DFFP is known in agriculture as a herbicide. When applied alone at rates in the range of 100 to 250 g/ha, diflufenzopyr causes moderate herbicidal effects in a number of plant species. DFFP acts as an inhibitor of auxin transport in higher plants [cf. Weed Science Vol. 45, 621-627 (1997)]. The herbicidal usefulness of diflufenzopyr is much more evident in combination with auxin-type herbicides, such as dicamba [Bowe et al., Proceedings of the Brighton Pest Control Conference - Weeds, BCPC, pp. 35-40 (1999)].

When combined with strobilurin type fungicides diflufenzopyr increases the fungicidal activity of the strobilurin. In WO 98/41094 certain combinations of strobilurins and diflufenzopyr are disclosed.

At very low dosages of 10 to 5,000 mg/ha diflufenzopyr can be used to increase fruit set and yield in crop plants such as cotton and soybean [cf. WO 01/43544].

It was an object of the invention to enhance the resistibility of crop plants against bacterial and/or fungal diseases in order to reduce the need for potentially harmful agro- chemicals.

It has now been found that treating crop plants with low, non-phytotoxic dosages of diflufenzopyr results in lowered incidences of bacterial and fungal pathogens later in the season, although diflufenzopyr itself has no relevant bactericidal or fungicidal activity.

Moreover, the invention relates to a method for controlling harmful fungi using mixtures of diflufenzopyr and compounds Il and/or III by using the mixtures according to the invention and the use of the compounds I with compounds Il and/or III for preparing such mixtures, and also to compositions comprising these mixtures. In the method according to the invention, diflufenzopyr is preferably taken up via the leaves of the plants and distributed throughout the plant with the sap.

This is why the effect after using the method according to the invention is not only ob- served in those plant parts which were sprayed directly, but the resistibility to bacterial and/or fungal diseases is increased throughout the plant.

In a preferred embodiment of the method, the foliage are treated with a formulation of diflufenzopyr.

In another preferred embodiment of the method, the seed is treated with a formulation of diflufenzopyr.

In another preferred embodiment of the method diflufenzopyr is applied in combination with a fungicide Il and/or bactericide III. Due to the effect of diflufenzopyr the amount of the other active ingredient can be lowered.

The active compounds diflufenzopyr and Il and/or III can be applied simultaneously, that is jointly or separately, or in succession, where, in the case of separate application, diflufenzopyr is preferably applied first.

Diflufenzopyr and the fungicide Il or bactericide III are usually applied in a weight ratio of from 1:1000 to 1:30, preferably from 1:1000 to 1 :50, especially 1 :500 to 1:100.

Depending on the type of plant to be protected, the application rate of diflufenzopyr is 50 mg to 10 g/ha, preferably from 100 mg to 2 g/ha.

For protecting monocotyledonous plants amounts of 100 mg to 10 g/ha, preferably between 100 mg and 5 g/ha diflufenzopyr are sufficient to enhance resistibility of the plants.

For protecting dicotyledonous plants amounts of 50 mg to 5 g/ha, preferably 100 mg to 2 g/ha diflufenzopyr are used.

If diflufenzopyr is applied in combination with a fungicide Il /and/or bactericide III such mixtures are, depending on the efficacy of the compound Il and/or III, applied from 5 g/ha to 1000 g/ha, preferably 50 to 900 g/ha, in particular 50 to 750 g/ha.

Correspondingly, the application rates for the compound Il or III are generally from 1 to 1000 g/ha, preferably from 10 to 900 g/ha, in particular from 20 to 750 g/ha. In the treatment of seed, application rates of diflufenzopyr are generally from 1 to 1000 mg/ 100 kg of seed, preferably from 1 to 750 mg/100 kg, in particular from 5 to 500 mg/100 kg.

In the treatment of seed, application rates of mixture are generally from 1 to 1000 g/ 100 kg of seed, preferably from 1 to 750 g/100 kg, in particular from 5 to 500 g/100 kg.

Diflufenzopyr either solo or in combination with the fungicides Il and/or bactericides III or the simultaneous, that is joint or separate, use of diflufenzopyr and the compounds Il and/or III are distinguished by being highly active against a wide range of phytopatho- genic fungi, in particular from the classes of the Ascomycetes, Deuteromycetes, Oo- mycetes and Basidiomycetes. They can be used in crop protection as foliar fungicides and as fungicides for seed dressing.

They are particularly important for protecting various cultivated plants, such as bananas, cotton, vegetable species (for example cucumbers, beans and cucurbits), barley, grass, oats, coffee, potatoes, corn, fruit species, rice, rye, soybeans, tomatoes, grapevines, wheat, ornamental plants, sugar cane and on a large number of seeds against multitude of fungi or bacteria.

Particularly advantageously, diflufenzopyr and mixtures containing it are suitable for the treatment of legumes, in particular soybeans and of cereals.

The method according to the invention is especially suitable for controlling of soybean diseases:

• soybean rust caused by Phakopsora pachyrhizi and Phakopsora meibomiae,

• powdery mildew caused by Microsphaera diffusa,

• Cercospora leaf blight and purple seed stain caused by Cercospora kikuchii,

• frogeye leaf spot caused by Cercospora sojina, • brown spot caused by Septoria glycines,

• anthracnose caused by Colletotrichum truncatum,

• target spot caused by Corynespora cassiicola,

• late season disease, a combination of Cercospora leaf blight and brown spot,

• bacterial blight caused by Pseudomonas syringae pv. glycinea,

and of cereal diseases, such as

• Bipolaris and Drechslera species,

• Blumeria graminis (powdery mildew),

• Fusarium and Verticillium species, • Mycosphaerella species,

• Pseudocercosporella herpotrichoides,

• Pseudoperonospora species, • Puccinia species,

• Rhizoctonia species,

• Septoria tr/t/c/ and Stagonospora nodorum, and

• Ustilago species.

When preparing the mixtures, it is preferred to employ the pure diflufenzopyr and compounds ll/lll, to which further active compounds against harmful fungi or against other pests, such as insects, arachnids or nematodes, or else herbicidal or growth- regulating active compounds or fertilizers can be added according to need.

Compounds Il and/or ill according to the invention are in particular fungicides and bactericides selected from the following groups:

• acylalanines, such as benalaxyl, metalaxyl, ofurace, oxadixyl, • amine derivatives, such as aldimorph, dodine, dodemorph, fenpropimorph, fen- propidin, guazatine, iminoctadine, spiroxamine, tridemorph,

• anilinopyrimidines, such as pyrimethanil, mepanipyrim or cyprodinil,

• antibiotics, such as cycloheximid, griseofulvin, kasugamycin, natamycin, polyoxin or streptomycin, • azoles, such as bitertanol, bromoconazole, cyproconazole, difenoconazole, dinitro- conazole, enilconazole, epoxiconazole, fenbuconazole, fluquinconazole, flusilazole, flutriafol, hexaconazole, imazalil, ipconazole, metconazole, myclobutanil, pencona- zole, propiconazole, prochloraz, prothioconazole, simeconazole, tebuconazole, tet- raconazole, triadimefon, triadimenol, triflumizol, triticonazole, • dicarboximides, such as iprodione, myclozolin, procymidone, vinclozolin,

• dithiocarbamates, such as ferbam, nabam, maneb, mancozeb, metam, metiram, propineb, polycarbamate, thiram, ziram, zineb,

• heterocyclic compounds, such as anilazine, benomyl, boscalid, carbendazim, car- boxin, oxycarboxin, cyazofamid, dazomet, dithianon, famoxadone, fenamidone, fenarimol, fuberidazole, flutolanil, furametpyr, isoprothiolan, mepronil, nuarimol, penthiopyrad, picobenzamid, probenazole, proquinazid, pyrifenox, pyroquilon, qui- noxyfen, silthiofam, thiabendazole, thifluzamid, thiophanate-methyl, tiadinil, tricy- clazole, triforine,

• copper fungicides, such as Bordeaux mixture, copper acetate, copper oxychioride, basic copper sulfate,

• nitrophenyl derivatives, such as binapacryl, dinocap, dinobuton, nitrophthal- isopropyl,

• phenylpyrroles, such as fenpiclonil or fludioxonil,

• sulfur, • other fungicides, such as benthiavalicarb, carpropamid, chlorothalonil, cyflufena- mid, cymoxanil, diclomezine, diclocymet, diethofencarb, edifenphos, ethaboxam, fenhexamid, fentin acetate, fenoxanil, ferimzone, fluazinam, fosetyl, fosetyl- aluminum, iprovalicarb, hexachlorobenzene, mandipropamid, metrafenone, pency- curon, propamocarb, phosphorous acid, phthalide, toloclofos-methyl, quintozene, zoxamide,

• strobilurins, such as azoxystrobin, dimoxystrobin, enestroburin, fluoxastrobin, kresoxim-methyl, metominostrobin, orysastrobin, picoxystrobin, pyraclostrobin or tri- floxystrobin,

• sulfenic acid derivatives, such as captafol, captan, dichlofluanid, folpet, tolylfluanid,

• cinnamides and analogous compounds, such as dimethomorph, flumetover or flu- morph, or

• resistance inductors such as acibenzoIar-S-methyl or prohexadione.

The compounds Il and III are well known and commercially available.

Preference is given to combined use of diflufenzopyr with a fungicide selected from the azoles or strobilurines as mentioned above. More preferred is the combined use of diflufenzopyr with one of the following fungicides: bromoconazole, cyproconazole, ep- oxiconazole, fenbuconazole, fluquiconazole, flusilazol, metconazole, myclobutanil, propiconazole, prochloraz, prothioconazole, tebuconazole, triticonazole, azoxystrobin, dimoxystrobin, fluoxastrobin, kresoxim-methyl, metominostrobin, orysastrobin, picoxystrobin, pyraclostrobin, trifloxystrobin.

What is usually used are mixtures of diflufenzopyr with a fungicide II. In certain cases, however, mixtures of diflufenzopyr with two or more compounds Il and/or III may be advantageous.

Diflufenzopyr is applied by treating seeds or shoots of the plants to be protected with an effective amount. Application can be effected both before and after infection of the plants or seeds. Prophylactic application is preferred.

In a preferred embodiment of the method, the plant is treated concomitantly with the application of the fungicide Il and/or bactericide III. A markedly reduced susceptibility of the plant to infection is observed.

The method for controlling harmful fungi is carried out in agricultural crops by the separate or joint application of diflufenzopyr and the compounds Il and/or III or of the mixtures of diflufenzopyr and the compounds Il and/or III, by spraying or dusting the seeds or the shoots of the plants before sowing or after emergence of the plants, resp. In permanent crops such as fruit trees or grapevines, the treatment is preferably carried out before or during the annual growth phase. The mixtures according to the invention, or the compound I and ll/lll, can be converted into the customary formulations, for example solutions, emulsions, suspensions, dusts, powders, pastes and granules. The use form depends on the particular intended purpose; in each case, it should ensure a fine and even distribution of the compound according to the invention.

The formulations are prepared in a known manner, for example by extending the active compound with solvents and/or carriers, if desired using emulsifiers and dispersants. Solvents/auxiliaries suitable for this purpose are essentially: - water, aromatic solvents (for example Solvesso products, xylene), paraffins (for example mineral oil fractions), alcohols (for example methanol, butanol, pentanol, benzyl alcohol), ketones (for example cyclohexanone, gamma-butyrolactone), pyrrolidones (NMP, NOP), acetates (glycol diacetate), glycols, fatty acid dimethylamides, fatty acids and fatty acid esters. In principle, solvent mixtures may also be used, carriers such as ground natural minerals (for example kaolins, clays, talc, chalk) and ground synthetic minerals (for example highly disperse silica, silicates); emulsifiers such as nonionogenic and anionic emulsifiers (for example polyoxyethylene fatty alcohol ethers, alkylsulfonates and arylsulfonates) and dispersants such as lignosulfite waste liquors and methylcellulose.

Suitable surfactants used are alkali metal, alkaline earth metal and ammonium salts of lignosulfonic acid, naphthalenesulfonic acid, phenolsulfonic acid, dibutylnaphthalenesulfonic acid, alkylarylsulfonates, alkyl sulfates, alkylsulfonates, fatty alcohol sulfates, fatty acids and sulfated fatty alcohol glycol ethers, furthermore condensates of sulfonated naphthalene and naphthalene derivatives with formaldehyde, condensates of naphthalene or of naphthalenesulfonic acid with phenol and formaldehyde, polyoxyethylene octylphenyl ether, ethoxylated isooctylphenol, octylphenol, nonylphenol, alkylphenyl polyglycol ethers, tributylphenyl polyglycol ether, tristearylphenyl polyglycol ether, alkylaryl polyether alcohols, alcohol and fatty alcohol ethylene oxide condensates, ethoxylated castor oil, polyoxyethylene alkyl ethers, ethoxylated polyoxypropylene, Iauryl alcohol polyglycol ether acetal, sorbitol esters, lignosulfite waste liquors and methylcellulose.

Substances which are suitable for the preparation of directly sprayable solutions, emulsions, pastes or oil dispersions are mineral oil fractions of medium to high boiling point, such as kerosene or diesel oil, furthermore coal tar oils and oils of vegetable or animal origin, aliphatic, cyclic and aromatic hydrocarbons, for example toluene, xylene, paraffin, tetrahydronaphthalene, alkylated naphthalenes or their derivatives, methanol, ethanol, propanol, butanol, cyclohexanol, cyclohexanone, isophorone, highly polar solvents, for example dimethyl sulfoxide, N-methylpyrrolidone and water. Powders, materials for spreading and dustable products can be prepared by mixing or concomitantly grinding the active substances with a solid carrier.

Granules, for example coated granules, impregnated granules and homogeneous granules, can be prepared by binding the active compounds to solid carriers. Examples of solid carriers are mineral earths such as silica gels, silicates, talc, kaolin, attaclay, limestone, lime, chalk, bole, loess, clay, dolomite, diatomaceous earth, calcium sulfate, magnesium sulfate, magnesium oxide, ground synthetic materials, fertilizers, such as, for example, ammonium sulfate, ammonium phosphate, ammonium nitrate, ureas, and products of vegetable origin, such as cereal meal, tree bark meal, wood meal and nutshell meal, cellulose powders and other solid carriers.

In general, the formulations comprise from 0.01 to 95% by weight, preferably from 0.1 to 90% by weight, of the active compounds. The active compounds are employed in a purity of from 90% to 100%, preferably from 95% to 100% (according to NMR spectrum).

The following are examples of formulations: 1. Products for dilution with water

A) Water-soluble concentrates (SL)

10 parts by weight of the active compounds are dissolved in water or in a water-soluble solvent. As an alternative, wetters or other auxiliaries are added. The active compound dissolves upon dilution with water.

B) Dispersible concentrates (DC)

20 parts by weight of the active compounds are dissolved in cyclohexanone with addition of a dispersant, for example polyvinylpyrrolidone. Dilution with water gives a dispersion.

C) Emulsifiable concentrates (EC)

15 parts by weight of the active compounds are dissolved in xylene with addition of calcium dodecylbenzenesulfonate and castor oil ethoxylate (in each case 5% strength). Dilution with water gives an emulsion.

D) Emulsions (EW, EO)

40 parts by weight of the active compounds are dissolved in xylene with addition of calcium dodecylbenzenesulfonate and castor oil ethoxylate (in each case 5% strength). This mixture is introduced into water by means of an emulsifying machine (Ultraturrax) and made into a homogeneous emulsion. Dilution with water gives an emulsion.

E) Suspensions (SC, OD)

In an agitated ball mill, 20 parts by weight of the active compounds are comminuted with addition of dispersants, wetters and water or an organic solvent to give a fine active compound suspension. Dilution with water gives a stable suspension of the active compound.

F) Water-dispersible granules and water-soluble granules (WG, SG)

50 parts by weight of the active compounds are ground finely with addition of dispersants and wetters and prepared as water-dispersible or water-soluble granules by means of technical appliances (for example extrusion, spray tower, fluidized bed). Dilution with water gives a stable dispersion or solution of the active compound.

G) Water-dispersible powders and water-soluble powders (WP, SP) 75 parts by weight of the active compounds are ground in a rotor-stator mill with addition of dispersants, wetters and silica gel. Dilution with water gives a stable dispersion or solution of the active compound.

2. Products to be applied undiluted

H) Dustable powders (DP)

5 parts by weight of the active compounds are ground finely and mixed intimately with 95% of finely divided kaolin. This gives a dustable product.

I) Granules (GR, FG, GG, MG)

0.5 part by weight of the active compounds is ground finely and associated with 95.5% carriers. Current methods are extrusion, spray-drying or the fluidized bed. This gives granules to be applied undiluted.

J) ULV solutions (UL)

10 parts by weight of the active compounds are dissolved in an organic solvent, for example xylene. This gives a product to be applied undiluted.

The active compounds can be used as such, in the form of their formulations or the use forms prepared therefrom, for example in the form of directly sprayable solutions, powders, suspensions or dispersions, emulsions, oil dispersions, pastes, dustable products, materials for spreading, or granules, by means of spraying, atomizing, dusting, spreading or pouring. The use forms depend entirely on the intended purposes; they are intended to ensure in each case the finest possible distribution of the active compounds according to the invention.

Aqueous use forms can be prepared from emulsion concentrates, pastes or wettable powders (sprayable powders, oil. dispersions) by adding water. To prepare emulsions, pastes or oil dispersions, the substances, as such or dissolved in an oil or solvent, can be homogenized in water by means of a wetter, tackifier, dispersant or emulsifier. However, it is also possible to prepare concentrates composed of active substance, wetter, tackifier, dispersant or emulsifier and, if appropriate, solvent or oil, and such concentrates are suitable for dilution with water.

The active compound concentrations in the ready-to-use preparations can be varied within relatively wide ranges. In general, they are from 0.0001 to 10%, preferably from 0.01 to 1%.

The active compounds may also be used successfully in the ultra-low-volume process (ULV), it being possible to apply formulations comprising over 95% by weight of active compound, or even to apply the active compound without additives.

Oils of various types, wetters, adjuvants, herbicides, fungicides, other pesticides, or bactericides may be added to the active compounds, even, if appropriate, not until immediately prior to use (tank mix). These agents are typically admixed with the compositions according to the invention in a weight ratio of from 1 :10 to 10:1.

The compounds I and ll/lll or the mixtures or the corresponding formulations are applied by treating the harmful fungi, the plants, seeds, soils, areas, materials or spaces to be kept free from them with a fungicidally effective amount of the mixture or, in the case of separate application, of the compounds I and II. Application can be carried out before or after infection by the harmful fungi.

The fungicidal effect of diflufenzopyr can be demonstrated by the following tests:

Example 1

The trial was conducted under field conditions. Seeds of soybean cv. "CD 205" were planted and grown under standard conditions with adequate supply of water and nutrients. Except for DFFP no other compounds were applied for pathogen control. Infection with pathogens occurred naturally. DFFP was applied twice, namely after 70 days and additional 16 days. Each treatment consisted of four parallels in a randomized block design. The disease incidences were evaluated 40 days after the second application (powdery mildew and late season disease). The dosages used and the obtained results are shown in Table 1.

Table 1

* rating: 0 = no damage 100 = 100% of leaf area damaged

(percentage of disease control in brackets).

Example 2

The trial was conducted under field conditions. Seeds of soybean cv. "CD 205" were planted and grown under standard conditions with adequate supply of water and nutrients. Except for DFFP no other compounds were applied for pathogen control. Infection with pathogens occurred naturally. DFFP was applied twice, namely after 60 days and additional 14 days. Each treatment consisted of four parallels in a randomized block design. The incidence of soybean rust was evaluated 35 days after the second application. The dosages used and the obtained results are shown in Table 2.

Table 2

rating: 0 = no damage 100 = 100% of leaf area damaged

(percentage of disease control in brackets).

The results obtained demonstrate that the incidence of several soybean diseases can be well controlled by low-dosage application of diflufenzopyr.

Claims

Claims

1. A method of enhancing resistibility of crop plants against bacterial and/or fungal diseases, which comprises treating the plants or seeds with low rates of 2-{1-[4- (S.δ-difluorophenyOsemicarbazonojethylJnicotinic acid, common name diflufen- zopyr.

2. The method of claim 1 , wherein diflufenzopyr is applied in amounts of 50 mg to 10 g/ha.

3. The method of claim 1 or 2, wherein diflufenzopyr is applied in amounts between 100 mg and 5 g/ha.

4. The method of claim 1 or 3, wherein the crop plants are legumes, especially soy- beans.

5. The method of claim 1 or 4, wherein diflufenzopyr is applied to the seeds in amounts of 1 to 1000 mg/ 100 kg.

6. The method of any one of claims 1 to 5, wherein diflufenzopyr is applied in combination with an azole fungicide in a weight ratio of 1:1000 to 1:30.

7. The method of any one of claims 1 to 5, wherein diflufenzopyr is applied in combination with a strobiluriri fungicide in a weight ratio of 1 :1000 to 1:30.

8. A mixture of diflufenzopyr and an azole fungicide selected from the group of bro- moconazole, cyproconazole, epoxiconazole, fenbuconazole, fluquiconazole, flusi- lazol, metconazole, myclobutanil, propiconazole, prochloraz, prothioconazole, te- buconazole, triticonazole in a weight ratio of 1:1000 to 1:30.

9. A mixture of diflufenzopyr and a strobilurine fungicide selected from the group of azoxystrobin, dimoxystrobin, fluoxastrobin, kresoxim-methyl, metominostrobin, orysastrobin, picoxystrobin, pyraclostrobin, trifloxystrobin in a weight ratio of

1 :1000 to 1:30.

10. A composition comprising a liquid or solid carrier and the mixture according to claim 8 or 9.

11. Seed, containing the mixture according to claim 9 or 10 in an amount between 1 and 1000 mg/ 100 kg.