AU749429B2 - Method for improving the health of banana plants - Google Patents

Description

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION NAME OF APPLICANT(S): Rhone-Poulenc Agroehimie ADDRESS FOR SERVICE: DAVIES COLLISON CAVE Patent Attorneys 1 Little Collins Street, Melbourne, 3000.

INVENTION TITLE: Method for improving the health of banana plants The following statement is a full description of this invention, including the best method of performing it known to me/us:la The subject of the present invention is a method for improving the health of banana plants and an agrochemical composition having the same aim.

The health of banana plants can be affected by various factors and mainly by the presence of diseases such as fusarium disease or cercosporiosis or alternatively by the presence of harmful nematodes.

More particularly, cercosporiosis of banana plants, caused by the fungi Mycosphaerella musicola and/or Mycosphaerella fijiensis, results in the appearance on the leaves of necroses which are yellow and/or brown in colour and then to a reduction in the number of leaves of the plants. This results in significant losses in the fruit yield of infected plantations.

Likewise, the nematodes result in a weakening of the plant which is prejudicial to the size of the 20 fruit yield.

Products such as mancozeb or chlorothalonil are known for their effectiveness against cercosporiosis capable of affecting banana plants.

However, it is always desirable to widen the 25 possibilities of choice offered to the grower, in order for the latter to find a solution which is best suited to his particular problem.

"The aim of the invention is therefore a method for improving the health of banana plants and more specifically a method for: preventively and/or curatively controlling cercosporiosis of banana plants, and/or P:\;PER bm\S\602-.242.doc-07/12A01 -2protecting banana plants against nematodes.

It has now been found that these aims could be achieved in all or in part by virtue of the treatment method according to the present invention.

Accordingly, the present invention provides a method of treating or preventing cercosporiosis in banana plants or for protecting banana plants against nematodes, which method comprises applying thereto an effective and non-phytotoxic dose of compound A, compound A being chosen from: a monoalkyl hydrogen phosphonate salt with a mono-, di- or trivalent metal cation, such as fosetyl-Al; and S- phosphorous acid and its alkali metal and S* alkaline-earth metal salts. Compound A is generally 15 applied to the aerial parts of the plants.

Fosetyl-Al is aluminium tris(O-ethyl phosphonate), described in "The Pesticide Manual", 9th edition, by Charles R. Worthing and Raymond J. Hance, published by the British Crop Protection Council.

20 In this specification, including the accompanying claims, an alkyl group is generally a straight chain or branched alkyl group having from 1 to 4 carbon atoms.

Compound A can be prepared by known methods or by analogy with known methods.

The dose of compound A applied is capable of varying within wide limits according to the weather conditions, the growth conditions and the frequency of the treatments carried out. For convenience, this dose is expressed as equivalent weight of phosphorous acid, of formula H 3

PO

3 applied per hectare. This dose is ,W7> generally between 0.350 and 10.4 kg/ha and preferably 3 between 0.630 and 7 kg/ha. The calculation, from this dose, of the dose of a specific compound A is conveniently carried out by taking into account the molar mass of the said compound and that of phosphorous acid. In the case where the specific compound A is a monoalkyl hydrogen phosphonate salt with a di- or trivalent metal cation, the valency number of the corresponding cation should also be taken into consideration.

According to an advantageous embodiment of the invention, compound A is fosetyl-Al. In this case, the dose of compound A, expressed as weight of fosetyl- Al applied per hectare, is between 0.500 and 15 kg/ha and preferably between 0.900 and 10 kg/ha.

According to a preferred embodiment of the :invention, the banana plants are affected by or capable of being affected by cercosporiosis.

In this case, the dose of compound A is also :.:related to the degree of infestation of the disease.

01 :0 20 This dose, also expressed as equivalent weight of phosphorous acid applied per hectare, is generally between 350 and 2450 g/ha and preferably between 630 and 2100 g/ha.

When, according to an advantageous embodiment 25 of the invention, the compound A applied is fosetyl-Al, the dose of compound A, expressed as weight of fosetyl- Al applied per hectare, is between 500 and 3500 g/ha and preferably between 900 and 3000 g/ha.

According to another preferred embodiment of the invention the banana plants are attacked by or susceptible to attack by nematodes. These nematodes are generally phytophagous nematodes of the order Tylenchida (in particular Aphelenchidae, Aphelenchoidae, Paraphlenchidae, Tylenchidae, Neotylenchidae, Hoplolaimdidae, Tylenchulidae, Criconematidae, Heteroderidae) and of the order Dorylaimida (in particular Dorylaimidae, Longidoridae, Trichodoridae). Compound A is particularly effective against nematodes of the order Tylenchida chosen from: Radopholus similis, Pratylenchus spp., Zygotylenchus tasmaninae, Hoplolaimus spp., Helicotylenchus multicinctus, Helicotylenchus spp., Meloidogyne spp., Rotylenchulus reniformis.

According to this embodiment, the dose of compound A, expressed as equivalent weight of phosphorous acid, is advantageously between 0.35 and 10.4 kg/ha and preferably between 1.4 and 7 kg/ha.

When, according to an advantageous embodiment of the invention, the compound A applied is fosetyl-Al, the dose of compound A, expressed as weight of fosetyl- Al applied per hectare, is between 0.5 and 15 kg/ha and preferably between 2 and 10 kg/ha.

Radopholus similis in particular causes a great deal of damage to banana plants. The method of the present invention is particularly effective against this parasite.

The compound A can be applied by spraying onto the aerial parts of the banana plants, by any means known per se, such as by a sprayer or alternatively by the aerial route. It can also be applied by sprinkling around the plants.

According to a preferred embodiment of the invention, the compound A is applied by injection.

This injection can be carried out into a section of the pseudostem of the banana plant, just after harvesting the bananas, by any means known per se. Pseudostem of the banana plant is understood to denote the stem of the banana plant, which is nonligneous in nature. Section of the pseudostem is therefore understood to mean the section obtained by cutting, at the time of harvesting the bananas, the pseudostem at a certain height above the ground (of between 1 and 2 The application by injection of the compound A into this section of the pseudostem can also be carried out simply by pouring a treatment liquid comprising compound A into a cavity, made in this section, of the order of 5 cm in depth. This application technique makes it possible to reduce the frequency of the treatments by carrying out 1 single treatment during the period separating the production of 2 crops of bananas by the same plant. It also makes it possible to carry out this treatment at the time of 20 harvesting the banana crops. This results in an appreciable saving in time for the farmers.

The injection can also be carried out into the pseudostem which develops following the abovementioned pseudostem and which will produce the next crop of bananas.

The present invention also provides the use of compound A for manufacturing agrochemical compositions for use in preventively and/or curatively controlling cercosporiosis of banana plants, and/or in protecting the banana plants against nematodes.

For its practical application to banana plants, the compound A is in fact used in the form of an agrochemical composition.

This agrochemical composition usually comprises from 0.5 to 95% by weight of compound A in combination with a vehicle which is acceptable in agriculture.

It can additionally comprise all the usual additives or adjuvants of plant-protection compositions, especially surface-active agents, adhesion agents and flow-improving agents.

In the present account, the term "vehicle" denotes a natural or synthetic, organic or inorganic material with which the active materials are combined to facilitate their application on the plant. This vehicle is thus generally inert and it must be acceptable in agriculture, especially on the treated plant. The vehicle can be solid (clays, natural or synthetic silicates, silica, resins, waxes, solid 20 fertilizers and the like) or liquid (water, alcohols, ketones, petroleum fractions, aromatic or paraffinic hydrocarbons, chlorinated hydrocarbons, liquefied gases, and the like).

The surface-active agent can be an 25 emulsifying, dispersing or wetting agent of ionic or non-ionic type. There may be mentioned, for example, salts of polyacrylic acids, salts of lignosulphonic acids, salts of phenolsulphonic or naphthalenesulphonic acids, polycondensates of ethylene oxide with fatty alcohols or with fatty acids or with fatty amines, substituted phenols (especially alkylphenols or arylphenols), salts of esters of sulphosuccinic acids, taurine derivatives (especially alkyltaurates) or phosphoric esters of polyoxyethylenated phenols or alcohols. The presence of at least one surface-active agent is desirable to promote dispersion of the active materials in water and their ready application on the plants.

This composition can also contain any kind of other ingredients such as, for example, protective colloids, adhesives, thickening agents, thixotropic agents, penetrating agents, stabilizing agents, sequestering agents, pigments, dyes or polymers.

More generally, the composition which can be used in the process according to the invention and/or subject of the invention can include all the solid or liquid additives corresponding to the usual techniques for the formulation of plant-protection products.

This composition can be in the solid, gel or liquid form and, in the latter case, in the form of o• o solutions or suspensions. Liquid compositions are 20 preferred, due both to their convenience of use and to their simplicity of manufacture.

r ~There may be mentioned, as forms of solid compositions, powders for dusting or dispersion (with an active compounds content which can range up to 25 100%), wettable powders and granules for dry spreading, as well as dispersible or soluble granules.

0S** SWettable powders (or powders to be sprayed),

S

as well as dispersible granules, generally contain to 95% of active materials and, in addition to the solid vehicle, from 0 to 5% of a wetting agent, from 3 to 10% of a dispersing agent and, when necessary, from 0 to 10% of one or more stabilizing agents and/or other 8 additives, such as pigments, dyes, penetrating agents, adhesives, or anticlumping agents, and the like. It is well understood that some of these compositions, such as wettable powders or dispersible granules, are intended to constitute liquid compositions at the time of application.

There may be mentioned, as forms of liquid compositions, solutions, in particular water-soluble concentrates, suspension concentrates or pastes.

The soluble concentrates most often comprise to 80% of-active material, the solutions ready for application containing, for their part, 0.01 to 40% of active material. As has already been said, aqueous dispersions, for example the compositions obtained by diluting a wettable powder according to the invention with water, come within the general scope of the present invention.

The suspension concentrates, also applicable by spraying, are a stable fluid product, which does not thicken or form a sediment after storage, and they generally contain from 10 to 75% of active materials, from 0.5 to 15% of surface-active agents, from 0.1 to of thixotropic agents and from 0 to 10% of suitable additives, such as pigments, dyes, antifoaming agents, corrosion inhibitors, stabilizing agents, penetrating agents and adhesives and, as vehicle, water or an organic liquid in which the active materials are insoluble or nearly insoluble: certain organic solid materials or inorganic salts can be dissolved in the vehicle to aid in preventing sedimentation or as antigels for water.

The compositions described above are prepared according to processes known per se.

Thus, to obtain powders to be sprayed or wettable powders, the active materials are intimately mixed, in suitable mixers, with the additional substances and the mixture is milled with mills or other grinders. Powders to be sprayed are thereby obtained with advantageous wettability and suspensibility; they can be suspended in water at any desired concentration and these suspensions can be used very advantageously, in particular for application on the aerial parts of the plants.

Pastes or suspension concentrates can be produced in place of wettable powders. The conditions and modes of production and use of these pastes are similar to those of wettable powders or powders to be sprayed, part of the milling operation necessary simply being carried out in a liquid medium.

The dispersible granules are generally prepared by agglomeration or extrusion or compacting, in suitable granulation systems, of compositions of wettable powder type. The granules for dry spreading are generally obtained by impregnating a granulated vehicle with a solution or an emulsion of the active materials.

The following examples are given purely by way of illustration and without implied limitation of the advantageous properties of the method according to the invention.

Example 1 in vivo application of fosetyl-Al to Mycosphaerella musicola responsible for yellow cercosporiosis of banana plants: A fosetyl-Al wettable powder is used which comprises the following ingredients (dose expressed as weight/weight): fosetyl-Al ethoxylated alcohol impregnated at on precipitated silica sodium lignosulphonate 3% ethoxylated polyarylphenol fatty alcohol impregnated at on precipitated silica 2% aluminosilicate The test is carried out on a plot situated in a banana plantation in a tropical region.

The composition tested is applied by spraying onto the leaves of the banana plant from the beginning of the rainy season corresponding to the period when infestation by Mycosphaerella musicola is capable of taking place. The fosetyl-Al doses applied are shown in the table below.

This treatment is repeated 9 times, each of "the applications being separated by a time interval of 14 days.

The results are observed 14 days after the 10th treatment.

To do this, the leaf surface infected by the disease, expressed as of the total leaf surface, is determined by visual monitoring of the percentage of necrotized surface (yellow and brown regions) over all the leaves of the banana plants by comparison with a control banana plant (which has not received fungicidal treatment).

11 The results are collated in the following table.

Dose of fosetyl-Al applied Leaf surface infected (in g/ha) (in 1000 30.3 2000 32.8 3000 29.7 Control plant 56.3 Following a treatment carried out with a commercial chlorothalonil formulation, applied at a dose of 2000 g/ha and with the same procedure, an infected leaf surface equal to 34.7% was observed.

These results reveal that fosetyl-Al is highly effective against cercosporiosis of banana plants.

Example 2 in vivo application of the dipotassium salt of phosphorous acid to Mycosphaerella musicola responsible for yellow cercosporiosis of banana plants: A solution of the dipotassium salt of phosphorous acid at a concentration equal to 200 g/l (expressed as phosphorous acid equivalent) is used.

The test is carried out on a plot situated in a banana plantation in a tropical region.

The composition tested is applied by spraying onto the banana plant leaves from the beginning of the rainy season corresponding to the period when infestation by Mycosphaerella musicola is capable of taking place. The dose of dipotassium salt of phosphorous acid applied is 650 g/ha (expressed as phosphorous acid equivalent).

This treatment is repeated 4, 5 or 6 times, each of the applications being separated by a time interval of 21 days.

In order to observe the results, the leaf surface infected by the disease, expressed as of the total leaf surface, is determined by visual monitoring of the percentage of necrotized surface (yellow and brown regions) on the 5th or the 6th leaf of the banana plants (recorded as L5 or L6 respectively) by comparison with a control banana plant (which has not received fungicidal treatment).

The results are collated in the table below.

The abbreviations used in this table have the following meaning: 19DAT5 result observed 19 days after the 5th treatment; 12DAT6 result observed 12 days after the 6th treatment; 20DAT7 result observed 20 days after the 7th treatment.

Infected leaf surface results (as 19DAT5 12DAT6 20DAT7 L6 L5 L6 Treated plant 6 30 15 37.5 37 Control plant 24 43 39 58 69 13 These results show that the dipotassium salt of phosphorous acid is highly effective against cercosporiosis of banana plants.

Example 3 Application by injection of fosetyl-Al and effect on the nematodes of banana plants: This test is carried out on a banana plantation (Cavendish variety) in which the plants have reached a stage of regular production of fruits.

This plantation is treated 70 days before harvesting by injection of a suspension of fosetyl-Al into the pseudostem of the banana plants corresponding to a dose of 6.4 kg/ha.

On harvesting, a soil sample with a volume of 20 dm 3 is withdrawn in which 25 g of healthy roots are isolated, from where the living nematodes are extracted by flushing with water and filtering through sieves with a mesh size of 40 pn. The living nematodes are nematodes of the species Radopholus similis and are counted under a microscope. The number of nematodes is shown per 100 g of roots.

4,000 living nematodes are thus observed.

In comparison, the number of living nematodes of the same species, counted in an identical way for banana plants which have not been treated with fosetyl- Al, is 13,200.

The application of fosetyl-Al has thus made it possible to reduce the number of nematodes parasitizing the banana plants by Example 4 Application of fosetyl-Al by leaf spraying and effect on the nematodes of banana plants: 14 The test is carried out on a plantation of young banana plants (Giant Cavendish variety).

Three months after having planted these plants, they are treated by leaf spraying with a suspension of fosetyl-Al at the dose shown in kg/ha in the table below.

This treatment is repeated after 10 days and after 40 days.

The results are observed 3 weeks after the last treatment in the same way as in Example 3.

The results are combined in the following table with the indication of the effectiveness calculated as being the difference between the number C of nematodes measured for the control test and this same number corresponding to the application of a fixed dose of fosetyl-Al, i.e. N, the said difference being divided by C.

Number of nematodes Effectiveof the species ness of Radopholus similis the per 100 g of roots treatment (in Dose of 2.5 9,800 52 fosetyl-Al (kg/ha) 10,000 51 10,000 51 E rl es 20,500 Example 5 Application of fosetyl-Al by sprinkling the bases of banana plants and effect on the nematodes: The test is carried out on a banana plantation (Cavendish variety) in which the banana plants have reached a stage of regular production of fruits.

The bases of the banana plants are sprinkled with a suspension of fosetyl-Al corresponding to a dose expressed in.kg/ha in the table below.

The results are observed 60 days after the treatment in the same way as in Example 3.

The results are collated in the following table with the indication of the effectiveness calculated as in Example 4.

e *o o o *oo Number of nematodes of the species Radopholus similis per 100 g of roots Effectiveness of the treatment (in Dose of fosetyl -Al (kg/ha) 3.2 6,000 4 8,000 77 4.8 9,000 5.6 7,000 81 6.4 1,000 a.

a J J.

Control test 136,000 1 Examples 3 to 5 consequently show a real decrease in the number of nematodes of the species Radopholus similis resulting from the application to the banana plant of fosetyl-Al.

a a P:OPERXKbhmXl082-96.242.doc-07/12/M -16A- Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that that prior art forms part of the common general knowledge in Australia.

Claims (24)

1. Method of treating or preventing cercosporiosis in banana plants or for protecting banana plants against nematodes, which method comprises applying thereto an effective and non-phytotoxic dose of compound A, compound A being chosen from: a monoalkyl hydrogen phosphonate salt with a mono-, di- or trivalent metal cation, such as fosetyl- Al; and phosphorous acid and its alkali metal and alkaline-earth metal salts.

2. Method according to claim 1 wherein compound A is i 15 applied to the aerial parts of the plants.

3. Method according to Claim 1 or 2 wherein the dose of compound A, expressed as equivalent weight of phosphorous acid, is between 0.35 and 10.4 kg/ha.

4. A method according to claim 3 wherein the dose of compound A is between 0.63 and 7 kg/ha.

Method according to any one of claims 1 to 4, wherein compound A is fosetyl-Al.

6. Method according to Claim 5, wherein the dose of fosetyl-Al is between 0.500 and 15 kg/ha.

7. Method according to claim 6, wherein the dose of fosetyl-Al is between 0.900 and 10 kg/ha. P:OPER\Kbm.56082-96.242.doc.07/1201 -18-

8. Method according to any one of Claims 1 to 7, wherein said method is for the treatment or prevention of cercosporiosis.

9. Method according to Claim 8, wherein the dose of compound A, expressed as equivalent weight of phosphorous acid, is between 350 and 2450 g/ha.

Method according to claim 9, wherein the dose of compound A is between 630 and 2100 g/ha.

11. Method according to any one of Claims 8 to wherein compound A is fosetyl-Al applied at a dose of between 500 and 3500 g/ha.

12. Method according to claim 11 wherein said fosetyl- Al is applied at a dose of between 900 and 3000 g/ha. *i

13. Method according to any one of Claims 1 to 7, 20 wherein said method is for protecting banana plants :o that are attacked by or susceptible to attack by nematodes.

14. Method according to Claim 13, wherein the dose of compound A, expressed as equivalent weight of phosphorous acid, is between 0.350 and 10.4 kg/ha.

Method according to claim 14 wherein the dose of compound A is between 1.4 and 7 kg/ha.

16. Method according to any one of claims 13 to Swherein compound A is fosetyl-Al applied at a dose of P:\OPER\KbmU6O82-96 spc2.doc-30/0402 -19- between 0.5 and 15 kg/ha.

17. Method according to claim 16 wherein fosetyl-Al is applied at a dose of between 2 and 10 kg/ha.

18. Method according to any one of claims 13 to 17, wherein the nematodes are of the species Radopholus similis.

19. Method according to any one of Claims 1 to 18, wherein compound A is applied by injection into the pseduostem of the banana plants.

20. Method according to any one of Claims 1 to 18, 15 wherein compound A is applied by sprinkling around the banana plants.

21. Compound A as defined in Claim 1 when used for preventively and/or curatively controlling cercosporiosis of banana plants, and/or protecting the banana plants against nematodes.

22. Use of compound A as defined in claim 1 in the manufacture of agrochemical compositions for 25 preventively and/or curatively controlling cercosporiosis of banana plants, and/or protecting the banana plants against nematodes.

23. A method according to claim 1, substantially as hereinbefore described with reference to the Examples. P:AOPERMWbn560S2-96 p,2.dmc-30/04/0l2 20

24. Compound A according to claim 21, substantially as hereinbefore described with reference to the Examples. DATED this 30th day of April, 2002 RHONE-POULENC AGRO by DAVIES COLLISON CAVE Patent Attorneys for the Applicant(s)