NOVEL PLANT PROTECTING COMPOSITIONS AND USES THEREOF

The invention relates to a plant protecting composition or agricultural pesticide, comprising a substance which is selected from the group comprising poly(alkyl)guanidines, poly(alkyl)biguanidines, polyguanines or octenidin, or any blends of substances of this group. In a preferred embodiment, the substance which is selected from the group comprising poly(alkyl)guanidines, poly(alkyl)—biguanidines, polyguanines or octenidin, or any blends of substances of this group, is present in combination with at least one other component exhibiting activity against agricultural pests. Said least one other component exhibiting activity against agricultural pests may represent at least one active agent of a commercially known pesticide. A further aspect of the invention relates to a method for protecting plants against plant pathogens comprising the application of the above agricultural pesticide compositions.

TECHNICAL FIELD

The present invention relates to a plant protecting agent or composition, based on a chemical active agent or a composition of chemical active agents.

Plant protecting agents are commonly defined as pesticides and herbicides which are in particular applied for the protection of plants, more specifically chemical or biological agents and compositions which are designed:1) to protect plants and plant products against pathogenic organisms or to prevent their action;2) to influence the life/vitality of plants in some other manner (e.g. growth regulators);3) to preserve plant products (e.g. seed protecting agents);4) to destroy undesired plants or parts of plants or to inhibit or prevent any undesirable growth of plants (herbicides).

The present invention relates in particular to a plant protecting agent according to group 1 above, which is based on a chemical agent or a composition of chemical agents. The corresponding pathogenic organisms are usually denominated as plant pathogens.

PRIOR ART

A variety of plant protecting agents of group 1 are known in the prior art.

Some of these known and commercially available agricultural pesticides can only be applied in relatively low dosages and under strictly controlled conditions due to their toxicity for, e.g. fish stock, animals, other organisms, plants in the soil etc.

Also an issue for a number of commercially available agricultural pesticides is the development of resistances by many pathogenic microorganisms. Thus, there remains a strong need for further chemical agents or chemical compositions having activity against plant pathogens and this is reflected by ongoing research and development efforts.

The main objects of the present invention are to provide a plant protecting agent or agricultural pesticide which is effective against plant pathogens and concurrently is not or hardly toxic for other plants or organisms in the required ranges of concentration for the contemplated application as a plant protecting agent.

These objectives are achieved by an agricultural pesticide having the features of claim1or claim4. Further aspects of the invention and more specific embodiments are the subject of further claims.

DESCRIPTION OF THE INVENTION

The agricultural pesticide according to claim1comprises a substance from the group of poly(alkyl)guanidines (alternatively denoted or known as poly(alkylen)guanidines), poly(alkyl)biguanidines (or poly(alkylen)biguanidines), polyguanines or octenidin or any blends of substances of this group.

These substances are advantageous in that they are exhibiting antimicrobial activity but are not toxic for humans and animals, at least not in the required ranges of concentration for the contemplated application as a plant protecting agent.

In particular, the substances used according to the present invention show a broad-spectrum effect against bacteria, fungi and viruses in the field of plant pathogens.

The advantageous broad-spectrum effect of these substances, in particular poly(hexamethylen)guanidine (PHMG) and poly-(hexamethylen)biguanidine (PHMB), is especially surprising since the anti-bacterial effect of such poly(alkyl)guanidines or poly(alkyl)biguanidines was previously only known with respect to some specific bacteria, in particular human-pathogenic bacteria such asStaphylococcus aureus, Pseudomonas aeruginosaandSalmonella choleraesuis.

The anti-bacterial activity of the cationic polymer poly-(hexamethylen) guanidine-hydrochloride (PHMGH) against human pathogenic microorganisms with respect to iatrogenic infections was described in this context for example in the following publication (Journal of Medical Microbiology (2008), 57, 1523-1528: “Polyhexamethylene guanidine hydrochloride-based disinfectant; a novel tool to fight meticillin-resistantstaphylococcus aureusand nosocomial infections”, Mathias K. Oule et al.). In particular, the publication “Mathias K. Oule et al.” addresses the antimicrobial effectivity of PHMGH as a novel tool for fighting a meticillin-resistant human-pathogenicStaphylococcus aureus.

The term “plant-pathogen” in the context of the present invention refers to microorganisms, in particular bacteria, fungi and viruses, which act as pathogenic organisms against plants or plant products.

Many plant pathogens, such as for example fungi, are spore forming organisms. Especially surprisingly, it has been found that the agricultural pesticide according to the invention shows a high antimicrobial activity against a broad variety of spore forming organisms.

The agricultural pesticide according to the invention has for example shown to be effective in particular against plant pathogens like the bacteriumErwinia amylovora(fire blight), the fungusPhytophthora infestans(late blight),Venturia inaequalis(apple scab) and ascomycetes of the generaFusarium. However, the applicability of the claimed agricultural pesticide is by no means limited to these organisms and a variety of further target pathogens are disclosed below.

In a preferred aspect of the present invention, the agricultural pesticide represents a composition wherein the substance which is selected from the group comprising poly(alkyl)guanidines, poly(alkyl)biguanidines, polyguanidines or octenidin, or any blends or substances of these groups is present in combination with at least one other component exhibiting activity against agricultural pests.

More specifically, said other component exhibiting activity against agricultural pests represents a commercially known or available pesticide or at least one active agent of a commercially known or available pesticide.

It has been found that by the means of such a combination the dosage of a plurality of commercially available pesticides can be reduced up to 90% without loss of the antimicrobial effectivity.

Further, it has even been demonstrated that for a number of commercially available agricultural pesticides an increase of the antimicrobial activity can be achieved while still applying the same dosage of those pesticides (albeit in combination with the substances of claim1). This is in particular advantageous, since usually an increase of the antimicrobial activity of such commercial pesticides is not possible by just increasing the dosage of the commercial pesticides due to strict regulatory limits.

Further commercial products beyond these categories according to FRAC are Vegas, Dynali, Capalo, Fleity, Vivando. The categorisation “contact agent” is based on the application form by means of contacting the surface of plants.

Typically, in the agricultural pesticide according to the present invention said least one other component exhibiting activity against agricultural pests is selected from the group of compounds comprising azoles, in particular diazoles, triazoles, benzimidazoles, and pyrazoles, carbamates, in particular benzimidazole carbamates and dithiocarbamates, carboxamides, dicarboximides, anilides, nicotinamides, amines and ammonium compounds, including spiroketalamines and heterocyclic compounds such as pyrimidines, pyridines, piperidines, morpholines, pyrroles, in particular phenylpyrroles, diazines, strobulines, nitriles, in particular chloronitriles, cinnamic acids.

The agricultural pesticide according to the present invention comprising a substance which is selected from the group comprising poly(alkyl)guanidines, poly(alkyl)biguanidines, polyguanines or octenidin, or any blends of substances of this group, may be present in an aqueous formulation in a proportion between 10 ppm and 500.000 ppm, preferably between 10 ppm and 200.000 ppm, more preferably between 20 ppm and 40.000 ppm, of the total composition.

For example, when the poly(alkyl)guanidine, in particular PHMG, is applied in an aqueous formulation, typically it is comprised therein in a proportion between 10 ppm to 200.000 ppm, more preferably between 20 ppm to 40.000 ppm.

Preferred ranges for an exemplary composition based on PMHG as a representative of the poly(alkyl)guanidines are compiled in the following Table 1:

Preferably, the agricultural pesticide according to the invention is adjusted to a pH value in the range of 3 to 8.

As already mentioned above, in a preferred aspect of the present invention the agricultural pesticide represents a composition wherein the substance which is selected from the group comprising poly(alkyl)guanidines, poly(alkyl)-biguanidines, polyguanidines or octenidin, or any blends or substances of these groups is present in combination with at least one other component exhibiting activity against agricultural pests.

In this case, the substance which is selected from the group comprising poly(alkyl)guanidines, poly(alkyl)biguanidines, polyguanines or octenidin, or any blends of substances of this group, is typically present in a proportion between 10 ppm and 200.000 ppm, preferably between 20 ppm und 8000 ppm, of the total composition.

For example, PHMG is typically comprised in combination with an active agent of a commercially available agricultural pesticide in a formulation preferably between 10 to 200.000 ppm, more preferably comprised between 20 and 8.000 ppm.

In such a composition, the least one other component exhibiting activity against agricultural pests is typically present in a proportion between 5 ppm and 20.000 ppm, preferably between 10 ppm und 5000 ppm, of the total composition.

In the agricultural pesticide according to the present invention, the poly(alkyl)guanidines, poly(alkyl)biguanidines or polyguanines may have a molecular weight in the range from 500 to 100.000 Dalton, such as 500 or 1000 to 40.0000 Dalton, preferably 500 or 1000 to 10.000 Dalton, 500 to 6.000 Dalton or 1000 to 4.000 Dalton.

In the agricultural pesticide according to the present invention, the poly(alkyl)guanidines or poly(alkyl)-biguanidines may have an alkyl(en) chain length of the monomer in the range from C2to C20, preferably in the range from C2to C14, and a degree of polymerisation n (number of monomeric alkylen units in the polymer) in the range from 5 to 600, preferably in the range from 5 to 300.

In particular, the poly(alkyl)guanidine may be selected from the group comprising a poly(tetramethylen)guanidine, poly(hexamethylen)guanidine (PHMG), a poly(octamethylen)-guanidine, poly(decamethylen)guanidine, poly(dodeca-methylen)guanidine or blends thereof.

Some specific embodiments of the agricultural pesticide according to the present invention are aqueous compositions comprising poly(hexamethylen)guanidine in an amount of 20-8000 ppm, and one or more of compounds selected from the group comprising 2,6-dichloro-N-[3-chloro-5-(trifluoro-methyl)-2-pyridylmethyl)benzamide, 5,10-dihydro-5,10-dioxonaphtho[2,3-b]-1,4-dithi-in-2,3-dicarbonitrile, methyl (E)-2-{2[6-(2-cyanophenoxy)pyrimidin-4-yloxy)phenyl}3-methoxyacrylate, propyl-3-(dimethylamino)propylcarbamate hydrochloride in an amount of 10-1000 ppm each and the balance of water.

Preferred ranges for an exemplary composition of active agents according to the invention based on a blend of PHMG with the commercially available pesticide active agent Dithianon (Delan®, Bayer) from the class of “contact agents” are:

Preferred ranges for an exemplary composition of active agents according to the invention based on a blend of PHMG with the commercially available active agents Fluopicolid/Propamocarb-hydrochlorid (Infinito®, Bayer) from the class of “contact agents” are:

Preferred ranges for an exemplary composition of active agents according to the invention based on a blend of PHMG with the commercially available pesticide agent Azoxystrobin (Amistar®, Syngenta) from the class of Strobilurines are:

Further suitable blends of PHMG with active agents of commercially available pesticides are compiled in Table 5 below.

The given proportions refer to a spray mixture which is typically applied in an amount of 1000 l/ha.

In Table 6 below a number of commercially available pesticides which are suitable for blending with poly(alkyl)guanidines, in particular PHMG, in the compositions according to the present invention, as well as suitable proportions in spray mixtures are compiled.

The agricultural pesticide according to the present invention may exhibit activity against any kind of agricultural pest, typically the agricultural pest is a microorganism, in particular selected from the group comprising bacteria, fungi and viruses.

A further aspect of the present invention relates to a method for protecting plants, in particular cultivated plants, against pests, comprising contacting the plants to be protected and/or the soil or nutrient medium wherein said plants are grown, with the agricultural pesticide as defined above for a predetermined time and in a sufficient amount to prevent or inhibit a harmful effect of said pests on the plants to be protected.

Typically, in this method the pesticide formulation is applied at least once in an amount of 100-5000 l, preferably 500-1500 l, per ha soil or nutrient medium.

TheBotrytis cinereaisolate BC 271 (which is resistent against strobilurines, anilinopyrimidines, hydrogenase inhibitors, Fenhexamide and has a reduced sensitivity against Fludioxonil) was cultivated on agar until the production of spores commenced. A spore concentration of 1×105conidiospores/ml was used for the tests.

The respective analyte (see Table 7 for a compilation of various tested analytes and standards) was added to the suspension of spores in the desired concentration and 10 μl (containing 1000 conidiospores) were placed on an agar plate (malt extract) in each repetition of the test, subsequently the plates were incubated at 20° C. Each test was repeated 4 times. The growth of fungi on the agar plates was examined after 2 days and 3 days (Table 8).

SUMMARY

After application of theBotrytisconidiospores onto agar plates, the spores germinated in the control as well as in the mixtures with Switch (0.1% and 0.01%), BasD30 (10%), ByIn312 (10%) and SynAm200 (10%), resulting in visible mycelium after 2 days and air mycelium after 3 days. After 3 days the colonies of the untreated control had grown to a size of ca. 4 cm diameter. 0.1% Switch decreased the growth of the partially resistentBotrytisstrain to ca. 1 cm and 0.01% Switch to 1.5-1.8 cm. (The growth of sensitiveBotrytisstrains on agar is completely inhibited by 0.1% Switch).

The analytes KAT P 2500, KAT P 1250, KAT P 625, TM PD 1250, TM PD 625, TM PI 1250, TM PI 625, TM PA 1250 and TM PA 625 (10% dilution each) completely inhibited the development of theBotrytisisolate Bc 271.

Infested leaves of an apple tree (Jonagold; originally harvested in the botanical garden of the University of Konstanz and further propagated in the greenhouse) which had been stored frozen were thawed and rinsed with water. The resulting suspension of conididospores was mixed with the various analytes (see Table 7 for a compilation of various tested analytes), so that the analytes were diluted 1:10, i.e. used in a concentration of 10%. 40 μl of each mixture were applied to aqueous agar and these plates were incubated at 20° C. for 24 h. Subsequently, for each test batch at least 200 conidiospores were assessed for germination using a microscope and the proportion of germinated conidiospores (percent) was calculated (Table 9). The tests were done as a double determination and were repeated once.

SUMMARY

The average germination rate of the conidiospores in the untreated control was 36.3%. ByIn312 was not able to inhibit germination of the spores. Each of the other analytes demonstrated a degree of efficacy against this pathogen above 98.5%. The reference standard Delan WG (dithianon) reduced the germination by 99.7% if applied in the recommended concentration of 0.05% and by 98.7% if applied in a concentration of 0.0005%.