Repellent composition for protecting seeds

Abstract

The invention relates to a method for protecting seeds from bird attacks, comprising coating the seeds with a formulation containing an extract obtained by macerating ground milkweed tissue.

Description

[0001] REPELLENT COMPOSITION TO PROTECT SEEDS

[0002] The invention relates to the field of protecting seeds against attacks by birds and to the treatment of these seeds with compounds of natural origin.

[0003] Brower and Fink (Ann NY Acad Sci. 1985;443:171-88) describe that the presence of cardenolides in certain butterfly species (page 173, 1st paragraph) has an emetic effect on birds. This effect is due to the presence of cardenolides accumulated by ingestion of milkweed leaves.

[0004] Brower et al (Science. 1968 Sep 27;161(3848):1349-50) show in particular that the emetic character of monarch butterflies varies according to the type of plants on which the larvae were raised.

[0005] Agrawal et al (Ecosphere 5(10), 2014) report a general study on potential correlations between cardenolide and latex expression in Asclepias. The conclusion reached is that these compounds have rather complementary functions. The compositions described in this document are not suitable for use as film-coating agents. Furthermore, this document does not describe the fact that asclepias ground material can be used as a plant protection product for its bird repellent effect.

[0006] Schaffer et al (Arch Environ Contam Toxicol. 1983 May;12(3):355-82) study the toxic properties of several chemical compounds towards birds.

[0007] Application WO2020 / 109529 describes the use of a crude extract of Asclepias, obtained by grinding Asclepias leaves and resuspension in water, in seed treatment or as a phytosanitary product and demonstrates the effectiveness of this solution as a bird repellent, without it being possible to conclude as to the technical characteristics of these compositions.

[0008] Karawya et al (Egyp. J. Pharm. Sci., 21, No. 1-2, pp 77-82) describes the extraction and analysis of the nature of cardenolides from Asclepias according to the extraction methods.

[0009] However, the use of ground material may involve the need to apply a large amount of substance to the seed, so there is an interest in obtaining more concentrated extracts, and therefore in extracting active substances from the plants, and in formulating these substances in order to obtain a formulation whose stability and concentration will be better controlled.

[0010] The invention therefore relates to a formulation derived from a crude extract of Asclepias and to its use in seed coating. Extraction from ground material may be carried out by various methods, in particular maceration. This invention also relates to an extract of Asclepias having undergone extraction and formulation steps, the extraction being able to be carried out by maceration.

[0011] This formulation can be used in film coating alone or in combination with other solutions, particularly with Guar gum and / or the bacterium Bacillus amyloliquefaciens IT45 - Rise P and / or an extract of another plant (in particular the AGRHO® GSB 30 extract of Cyamopsis psoraloides, which has marketing authorization in France). The seed treatment marketed by LG Semences under the name StarCover™ contains this IT45 bacterium and this Cyamopsis psoraloides extract.

[0012] The use of this solution can also be combined with cultural practices such as sowing a strip of peas near or in the same area as corn or sunflowers. Since peas are very attractive to birds, they divert them from corn or sunflowers from the time of sowing and during the early stages of growth (especially before and during germination) and thus limit damage to crops.

[0013] In the preferred embodiment, the extraction and formulation are carried out from ground Asclepias leaves, in particular Asclepias curassavica. This ground material may be obtained from fresh leaves, but dried leaves may also be used. Stems or any other part of the plant may also be used.

[0014] Thus, in another embodiment, latex from the plant is used as the basis of this extract. The method according to the invention is particularly suitable for protecting seeds from attacks by birds, which eat the seeds after sowing or at the time of germination. In particular, this effect is observed against corvids, in particular crows and ravens, in particular rooks and other bird pests. Thus, the method makes it possible to improve the overall yield of the harvest, due to the greater number of seeds remaining in the ground. The effect of the composition on birds is repellent, the birds no longer coming to eat the seeds and / or spitting them out.

[0015] The solution will also have an effect against rodents and other household pests. Thus, coating with this solution provides double protection to treated seeds. The use of this solution for its repellent effect against birds and rodents can be extended to other areas of activity.

[0016] The invention thus relates to a method for protecting plant seeds against bird attacks, comprising a step of film-coating the seeds before sowing with a formulation containing an extract obtained by maceration of an asclepias tissue, said extract being obtained by: a) bringing a raw material of an asclepias tissue into contact with an organic extraction solvent, in order to obtain an extract 1; b) optionally separating the biomass from the extract 1, to obtain a liquid fraction; and c) concentration steps to recover an extract 2 and removal of the organic extraction solvent.

[0017] The concentration of step c) is carried out on extract 1 or the liquid fraction obtained in b).

[0018] As indicated above, the method is preferably carried out on ground milkweed leaves and / or stems. In a preferred embodiment, ground milkweed leaves are used.

[0019] The implementation of the invention is carried out by using an organic solvent, allowing the extraction (solubilization) of cardenolides in said solvent during the maceration of the asclepias tissue.

[0020] Examples of solvents include n-hexane, cyclohexane, 1,4-dioxane, CCL, benzene, ethanol, methanol, diethyl ether, dichloromethane, or chloroform. In one embodiment, the maceration is carried out with a polar solvent. Acetone, ethanol, methanol, diethyl ether, dichloromethane, or chloroform can be used in particular. Chloroform is particularly suitable. The maceration solvent can also be substituted with a non-organic solvent (particularly water or an aqueous solvent).

[0021] Maceration of the milkweed tissue in the extraction solvent is preferably carried out at room temperature, or at a higher temperature, which can increase the solubility of the cardenolides contained in the milkweed tissue. However, the temperature is not desired to be too high, and it can be maintained between 25 and 80°C. The temperature is preferably below 70°C, more preferably below 60°C. The maceration can last between 30 minutes and 5 hours. In particular, a maceration time of between 1 hour and about 3 hours is particularly suitable. The extraction solvent can also be renewed during the maceration (for example once or twice), which can improve the yield. The different batches of solvent used for the maceration are then mixed to carry out the following steps.

[0022] In an optional but preferred embodiment, separation of the biomass in step b) is carried out by filtration, centrifugation or decantation. The objective of this step is to separate the liquid phase from the solid phase (asclepias tissue debris). It is also possible to implement a step of precipitation of components other than cardenolides (for example by adding a solution of lead acetate (used to eliminate by precipitation large molecules such as proteins, nucleic acids and organic acids) and monosodium or disodium phosphate (to eliminate excess lead in the supernatant), or by varying the pH), and recovery of the liquid fraction before implementing step c).

[0023] Step c) can be carried out for example by evaporation or by filtration, according to methods known in the art (evaporation of all or part of the extraction solvent for example using a reduced pressure evaporator, nano or ultra-filtration).

[0024] The extract obtained in step c) can also be freeze-dried, before rehydration for use in the production of the film-coating composition.

[0025] The method allows to obtain an extract which contains - 0.5 to 4% by weight of cardenolides, generally between 1 and 2% by weight of cardenolides, relative to the total weight of said extract (knowing however that this depends on the degree of evaporation)

[0026] - 10 to 85% by weight of dry matter, preferably between 50 and 70% by weight of dry matter, relative to the total weight of said extract

[0027] - 1 to 8% by weight of cardenolides, generally between 1.5 and 5%, or between 1.5 and 3.5% by weight, relative to the total weight of said dry matter and a viscosity of between 1 and 10000 mPa.s, generally between 300 and 600 mPa.s (the examples describe how to measure the viscosity).

[0028] In particular, the extract contains between 1 and 2% by weight of cardenolides, relative to the total weight of said extract, between 50 and 70% by weight of dry matter, relative to the total weight of said extract, between 1.5 and 5%, (or between 1.5 and 3.5%) by weight, relative to the total weight of said dry matter and a viscosity of between 300 and 600 mPa.s.

[0029] Seed coating is used for effective seed protection. Generally speaking, the active ingredients appropriate for the desired effect should be applied evenly over the entire surface of the seeds. In fact, if the surface of the grain is not completely covered by the products, including in the furrow, the protection could be less effective or even ineffective. In this case, however, since the milkweed extract has a repellent effect, this effect is observed even if the entire seed is not covered.

[0030] A seed treatment product is formulated by adding the active ingredient (here the milkweed extract obtained by maceration, as described above) to formulants, adjuvants, film-coating agents known in the art. These compounds have no biological effect and are used in particular to ensure good adhesion of the active ingredient to the seed, as well as good seed coverage.

[0031] Thus, the film coating is carried out by mixing the Asclepias extract with a formulant and / or a film-coating agent, and possibly a binder (preferably biodegradable, such as a vegetable oil or a biodegradable polymer). Then the mixture is sprayed onto the seeds, for application to the seeds, the homogenization then being generally carried out in static mixers.

[0032] Organic solvents or water, dispersants, emulsifiers, surfactants or wetting agents, pigments or dyes are used as formulants.

[0033] Film-coating agents are used to apply a microporous film to the surface of the seed. They improve seed coverage and the uniformity of the active ingredient. They can also facilitate seed flow in the seeder.

[0034] Coatings can change the shape, size and / or weight of the seed, thereby improving sowing accuracy.

[0035] A pigment or colorant can also be added, which makes it easy to identify coated seeds. Furthermore, birds, recognizing the color of the seeds and associating it with this repellent effect due to the presence of milkweed extract, are encouraged not to eat these seeds.

[0036] Single-layer lamination can be performed or the lamination steps can be repeated to obtain multi-layer lamination.

[0037] In a preferred embodiment, the plant is a grass.

[0038] In particular, the method is particularly suitable for wheat seeds.

[0039] The method can also be applied to barley, rye, corn, rapeseed or sunflower seeds, but this method also applies to cucurbit, solanaceous, brassica or asteraceae vegetable species.

[0040] The invention also relates to a composition or formulation for film-coating seeds, characterized in that it comprises an extract formulated from Asclepias, capable of being obtained by a method as described above, or obtained by such a method, and at least one film-coating agent or formulant. This composition has bird-repellent properties and is intended in particular for coating seeds, as described above, in order to protect the seeds from bird attacks. The invention relates to a method for preparing a composition (or formulation) for film-coating seeds comprising mixing an Asclepias extract described above with at least one formulant and / or one film-coating agent and optionally a binder.

[0041] The use of such a composition for coating seeds is also an object of the invention. The invention thus relates to a method for preparing a coated seed comprising the application of a coating formulation containing the asclepias extract described above to the surface of the seed.

[0042] The invention also relates to a seed coated with a film-coating composition, containing an extract obtained by maceration of asclepias tissue, as described above and which can be obtained by the method defined above. Thus, the seed is coated with a composition containing an extract obtained from asclepias tissue containing:

[0043] 0.5 to 4% by weight of cardenolides, generally between 1 and 2% by weight of cardenolides, relative to the total weight of said extract (knowing however that this depends on the degree of evaporation)

[0044] 10 to 85% by weight of dry matter, preferably between 50 and 70% by weight of dry matter, relative to the total weight of said extract

[0045] 1 to 8% by weight of cardenolides, generally between 1.5 and 5%, or between 1.5 and 3.5% by weight, relative to the total weight of said dry matter and a viscosity of between 1 and 10000 mPa.s, generally between 300 and 1000 mPa.s, or 300 and 600 mPa.s.

[0046] The invention also relates to the use of an extract containing

[0047] 0.5 to 4% by weight of cardenolides, generally between 1 and 2% by weight of cardenolides, relative to the total weight of said extract (knowing however that this depends on the degree of evaporation)

[0048] 10 to 85% by weight of dry matter, preferably between 50 and 70% by weight of dry matter, relative to the total weight of said extract

[0049] 1 to 8% by weight of cardenolides, generally between 1.5 and 5%, or between 1.5 and 3.5% by weight, relative to the total weight of said dry matter and a viscosity of between 1 and 10000 mPa.s, generally between 300 and 1000 mPa.s, or 300 and 600 mPa.s for coating seeds. As indicated above, the extract is used in a formulation suitable for this use. The invention also relates to the use of an extract containing

[0050] 0.5 to 4% by weight of cardenolides, relative to the total weight of said extract,

[0051] 10 to 85% by weight of dry matter, relative to the total weight of said extract,

[0052] 1 to 8% by weight of cardenolides, relative to the total weight of said dry matter, and a viscosity of between 1 and 10000 mPa.s, as a bird repellent, in particular to prevent birds from consuming seeds coated with the extract.

[0053] Finally, the invention relates to the use of this extract as a phytosanitary product, or the use of this extract for the preparation of a phytosanitary product. This phytosanitary product has a repellent activity against birds, and thus protects seeds. The invention thus relates to an extract obtained from Asclepias as a repellent agent against birds.

[0054] Description of figures

[0055] [Fig. 11: average consumption of control or coated corn with two BRF solutions at different doses, by Corvids in an aviary.

[0056] [Fig. 21: average consumption of control corn or corn coated with BRF2 solution after purification, by Corvids in an aviary.

[0057] [Fig. 31: average percentage of germinated seeds for the 5 test locations, the percentage is evaluated at stages BBCH11, BBCH13 and BBCH15, the percentage is expressed relative to the control (untreated control);

[0058] [Fig. 41: Average percentage of seeds damaged by birds for the 5 trial locations, the percentage is evaluated at stages BBCH11, BBCH13 and BBCH15, the percentage is expressed relative to the control (untreated control); The values ​​are normalized using the control, untreated seeds as a reference. Since the baseline is normalized to 100%, all seeds treated with a mixture with bird repellent properties will deviate from this baseline. For example, in Figure 3, 112.4% of the seeds treated with BRF dose Rate 3 (2N) germinated at stage BBCH15. This means that 12.4% more seeds germinated with this treatment compared to untreated seeds. Examples

[0059] It was shown in WO 2020 / 109529 that the application of a crude Asclepias ground material applied to wheat and corn seeds had a repellent effect on corvids.

[0060] Two experimental phases were conducted, on the one hand the verification of the presence of cardenolides in extracts from Asclepias and on the other hand the extraction by maceration of compounds from Asclepias and their formulation.

[0061] Example 1: Identification of cardenolides in Asclepias leaf extracts

[0062] An extraction by maceration assisted by ultrasound was carried out from 2g of plant powder, freeze-dried Asclepias curassavica leaves, in 3x10ml of methanol.

[0063] Three methods of cardenolide concentration, adapted from the literature, were tested:

[0064] Method adapted from Groeneveld et al., 1991, the extract diluted in a water / ethanol mixture was fractionated by liquid / liquid mixing with diethyl ether to obtain an aqueous phase (E1.1) and an organic phase (E1.2). The aqueous phase obtained was then sub-fractionated by liquid / liquid partitioning with chloroform to obtain an organic phase (E1.11) and an aqueous phase (E1.12);

[0065] Method adapted from Warashina et al., 1994., the extract diluted in a water / ethanol mixture was fractionated by liquid / liquid mixing with diethyl ether in order to obtain an aqueous phase (E1.T) and an organic phase (E1.2'). The aqueous phase obtained was then sub-fractionated on SPE (Solid Phase Extraction) in reverse phase with a first elution solvent consisting of a water:methanol mixture (50 / 50) (E1.T1) and a second consisting of methanol (E1.T2).

[0066] Method adapted from Roy et al., 2005, the extract was fractionated on normal phase SPE with a first elution with dichloromethane (E2.1), a second elution with a dichloromethane / ethyl acetate mixture (90 / 10) (E2.2) and a third elution with a dichloromethane / methanol mixture (90 / 10) (E2.3). The crude extract and the generated fractions were analyzed by liquid chromatography coupled with a mass spectrometer, using an electrospray ionization (ESI) mode. Table 1 represents the extraction yields of Asclepias curassavica plant powder and the different generated fractions.

[0067] [Table 1]

[0068] The main cardenolides were investigated by ion extraction. Table 2 represents the main cardenolides identified based on their mass spectra and literature data.

[0069] [Table 2]

[0070] Table 3 represents the other cardenolides, identified in some samples based on molecular ion extraction in ESI(+) mode. Main cardenolides identified based on their mass spectrum and literature data.

[0071] [Table 3]

[0072] Example 2: Preparation of an extract by maceration of Asclepias leaves

[0073] 10.5 g of crushed Asclepias curassavica leaves were introduced into a tank containing 297 g of chloroform. The medium was kept stirring at boiling point (approximately 61.2°C) for 3 hours.

[0074] After maceration, the liquid phase was separated from the biomass by centrifugation. 191 g of solution with a solids content of 5% were recovered. The diluted juice was then concentrated by evaporation of the solvent under vacuum. 170 g of chloroform were removed to leave 21 grams of a heterogeneous mixture containing the molecules of interest. 10 g of water were then added to this mixture. The chloroform removal was then continued by distillation. Approximately 11.5 g of chloroform were removed, along with 3.6 g of water, leaving 16 g of a dark aqueous mixture with a solids content of 60% in the flask.

[0075] The cardenolide content of the extract was measured at approximately 1.97% by weight using liquid chromatography-mass spectrometry. Uscharidin, calotoxin, asclepin, calotropagenin, calactin, uscharin, 12p-hydroxycoroglaucigenin, 12p-hydroxycalactropin, 15p-hydroxycalactin, and gofruside were detected.

[0076] To measure viscosity, 300g of extract at 25°C was weighed into a 600 mL beaker. A Brookfield RVDV viscometer was used at 20 rpm with a needle to ensure a reliable measurement. The viscosity of the extract was 400 mPas.

[0077] Example 3: Preparation of an extract by maceration of Asclepias leaves

[0078] 4.14 kg of dried biomass of crushed Asclepias curassavica leaves and stems were introduced into a tank containing 41.4 kg of water at 30°C. The medium was kept stirring at 30°C for 3 hours.

[0079] After maceration, the liquid phase was separated from the biomass by a decanter centrifuge. 36.1 kg of diluted juice with a dry extract of 2.44% was separated from the biomass. The biomass had a moisture content of 69.77%.

[0080] The pH of the diluted extract was 5.9. Approximately 0.27 kg of 75% by mass phosphoric acid was added to obtain a pH of 2.8. The solution was stirred and kept at 30°C for 30 minutes and the formation of flocs in the mixture was observed. The flocculated products were removed by centrifugation and 35.6 kg of clear juice with a dry extract of 2.65% was obtained. The pH of the juice was 2.7.

[0081] 0.7 kg of 30% mass lime milk was then introduced and led to the formation of hydroxyapatite as well as other calcium phosphate species almost instantaneously. The precipitate was removed by centrifugation. 33.7 kg of clarified juice with a dry extract of 2.06% was obtained.

[0082] 80 g of 30% by mass lime milk was added to the clarified juice to adjust the pH to 7.1. Hydroxyapatite was precipitated a second time. The precipitate was removed by centrifugation. 32.9 kg of juice with a dry extract of 1.97% was obtained. After 12 hours of storage at 30°C, the clear juice became turbid again with a drop in pH to 4.7. The juice was centrifuged again. 29.34 kg of clarified juice with a dry extract of 1.88% was recovered after centrifugation.

[0083] The diluted juice was then concentrated by distillation of water in a falling flow evaporator. 0.762 kg of concentrated juice with a dry extract of 64.2% was obtained. The cardenolide content was 1.13% by weight of cardenolides, relative to the total weight of said extract, measured by liquid chromatography coupled with mass spectrometry. Uscharidin, calotoxin, asclepin, calotropagenin, calactin, uscharin, 12p-hydroxycoroglaucigenin, 12p-hydroxycalactropin, 15p-hydroxycalactin and gofruside were detected.

[0084] To measure the viscosity, 300g of extract at 30°C was weighed into a 600 mL beaker (height 12.4 cm and diameter 9 cm). A Brookfield RVDV type viscometer was used at 20 rpm with a needle to be in the correct range for a reliable measurement. The viscosity of the formulation is 358 mPas.

[0085] Example 4. Formulation of the extract obtained by maceration of Asclepias leaves

[0086] To preserve the extract from microbial growth, 76.2 g of kathonTM CG (mixture of methylchloroisothiazolinone and methylisothiazolinone with a weight ratio of 3:1) (BIT, MIT) was added to the extract obtained in Example 3.

[0087] To ensure stability of the formulation over time, 0.57 kg of an ethoxylated fatty alcohol such as Rhodasurf® 860 / P (ethoxylated fatty alcohol 6 EO) and 1.5 kg of etho (30 EO)-propoxylated (20 PO) tristyrylphenol such as Soprophor® TSP / 461 were added. The pH was readjusted to 7 using potassium hydroxide. The cardenolide content of the resulting formulation was 1.08% by weight measured by liquid chromatography coupled with mass spectrometry.

[0088] The viscosity of the formulation is 1000 m.Pa.s.

[0089] To measure viscosity, 300g of extract at 25°C was weighed into a 600 mL beaker (height 12.4 cm and diameter 9 cm). A Brookfield RVDV type viscometer was used at 20 rpm with a needle to be in the correct range to obtain a reliable measurement.

[0090] Example 5. Application of the formula in seed treatment

[0091] To obtain a treated seed, a "treatment slurry" is prepared consisting of the composition of Example 4, a "film-forming agent" and water. This "film-forming agent" is composed of an adhesive (20 to 50% by weight), coloring elements (10 to 40% by weight) and 10 to 40% (by weight) of fillers. The seed is treated in a multi-layer manner, by applying several successive layers with an intermediate drying time (2 hours). This application is carried out in a SATEC-type bowl: the slurry including the raw ground Asclepias leaves is sprayed onto the seeds kept rotating in the bowl for a few seconds.

[0092] Example 6. Aviary evaluation of the repellent effect of treated seeds

[0093] Two batches of formulation according to example 5 were produced: BRF 1 produced in February 2020 and BRF2 produced in November 2020.

[0094] Tests were carried out on birds in aviaries according to the protocol described in WO 2020 / 109529 (examples 5 to 7).

[0095] The experiment is carried out on crows and rooks in aviaries (7 individuals per aviary, Crow and Rook), the test being carried out over three days:

[0096] On day 1, a balanced diet is offered to the birds (this diet is composed of 20g of kibble and control corn at will)

[0097] On day 2, 50g of control corn (coated with film-coating agent alone) is offered

[0098] On day 3, 20g of corn treated with the BRF solution are offered. On days 2 and 3, a weighing of the refused feed is carried out at the end of the day, to calculate the average consumption per animal. The results of the experiment with the BRF1 (2N) and BRF2 (1.5N) solutions are presented in Figure 1, the reduction in grain consumption for the BRF1 (2n) solution is 22% lower than that of the control.

[0099] The effect of the BRF2 solution is however limited. An additional purification step on this extract obtained the purified BRF2 1 and purified BRF2 2 solutions, new tests were carried out with seeds coated with these purified solutions, the results are presented in Figure 2. A reduction in consumption by 18 and 10% could be obtained for these two tests. This example shows that despite the poor result of the BREF2 solution, the purification of this solution makes it possible to obtain a repellent effect against birds.

[0100] Example 1. Germination of treated seeds

[0101] 5 treatment solutions were applied to Pmg 280 corn seeds.

[0102] [Table 4]

[0103] Table 4 describes the treatments applied to the seeds.

[0104] 5 field trials were conducted in Italy, observations were made at 3 different stages: BBCH 11, BBCH13 and BBCH 15. That is

[0105] BBCH 11 - first leaf spread

[0106] BBCH 13 - third leaf spread

[0107] BBCH 15 - fifth leaf spread

[0108] The observations focused on the percentage of germinated (emerged) seeds, the results below are the average obtained for the 5 test locations. The results are presented in Figure 3. The use of BRF has no phytotoxic effect on the seed and, on the contrary, allows the percentage of germinated seeds to be significantly increased. A 2N dosage of this solution allows an emergence identical to that obtained with KORIT.

[0109] Example 8. Effect of treatment on bird damage.

[0110] The experiment described in example 7 made it possible to measure the damage caused by birds; the results are in figure 4; the results are the average for the 5 test locations.

[0111] The two highest doses of BRF formulation significantly reduce the proportion of damaged seeds, the results tend towards a result similar to that obtained from KORIT.

[0112] Example 9. Influence of BRF on emergence

[0113] The experiment involved two varieties of Limagrain LG 30.258 (silage corn variety) and LG 31.377 (grain corn variety).

[0114] 5 conditions and 3 test locations were tested, the kinetics of plant emergence was monitored for each of the test locations. Seeds coated with a redigo and BRF combination had a similar behavior to those coated with a positive control mixture of Redigo associated with Korit. Untreated seeds showed a deficit in emergence compared to the other conditions of the experiment. Coating with Korit as BRF had no negative effect on seed germination.

[0115] In conclusion, an extract of asclepias, obtained by maceration, makes it possible to produce a film-coating composition which proves effective in preventing birds from eating seeds, without affecting seed germination.

Claims

Claims. Method for protecting plant seeds against bird attacks, comprising the step of coating the seeds before sowing with a formulation containing an extract obtained by macerating an Asclepias tissue, said extract being obtained by: a) contacting a raw material of an Asclepias tissue, in an organic extraction solvent, in order to obtain an extract 1; b) optionally separating the biomass of the extract 1, to obtain a liquid fraction; and c) concentrating the extract 1 or the liquid fraction to recover an extract 2 and removing the organic extraction solvent.

2. Method according to claim 1, characterized in that the fabric is a grind of Asclepias leaves and / or stem.

3. Method according to claim 1 or 2, characterized in that the organic solvent is chloroform.

4. Method according to any one of claims 1 to 3, characterized in that the separation in step b) is carried out by filtration, centrifugation or decantation.

5. A method according to any one of claims 1 to 4, characterized in that step c) is preceded by a step of precipitation of components other than cardenolides, and recovery of the liquid fraction 6. Method according to claim 5, characterized in that the precipitation step is carried out by adding a monosodium phosphate solution and a lead acetate solution.

7. A method according to any one of claims 1 to 6, characterized in that the extract contains - 0.5 to 4% by weight of cardenolides, relative to the total weight of said extract, - 10 to 85% by weight of dry matter, relative to the total weight of said extract, - 1 to 8% by weight of cardenolides, relative to the total weight of said dry matter, - and a viscosity between 1 and 10000 mPa.s.

8. Method according to any one of claims 1 to 7, characterized in that the plant is a grass, preferably wheat, barley, rye or maize.

9. Method according to any one of claims 1 to 8, characterized in that the plant is chosen from the group consisting of rapeseed, sunflower and vegetable species of the cucurbitaceae, solanaceae, brassicaceae or asteraceae families.

10. Method according to any one of claims 1 to 9, characterized in that the coating is carried out by mixing the extract obtained by maceration of an asclepias tissue with a formulator and / or a coating agent.

11. Coated seed with a coating composition containing an extract of milkweed tissue containing: - 0.5 to 4% by weight of cardenolides, relative to the total weight of said extract, - 10 to 85% by weight of dry matter, relative to the total weight of said extract, - 1 to 8% by weight of cardenolides, relative to the total weight of said dry matter, - and a viscosity between 1 and 10000 mPa.s.

12. Use of an extract containing - 0.5 to 4% by weight of cardenolides, relative to the total weight of said extract, - 10 to 85% by weight of dry matter, relative to the total weight of said extract, - 1 to 8% by weight of cardenolides, relative to the total weight of said dry matter, - and a viscosity between 1 and 10000 mPa.s, for coating seeds.

13. Use of an extract containing - 0.5 to 4% by weight of cardenolides, relative to the total weight of said extract, - 10 to 85% by weight of dry matter, relative to the total weight of said extract, - 1 to 8% by weight of cardenolides, relative to the total weight of said dry matter, and a viscosity between 1 and 10000 mPa.s as a bird repellent.

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