Use of extract of at least one red alga as nematicide and method for controlling plant pathogenic nematodes

Abstract

To provide a method for controlling plant pathogenic nematodes using an extract of at least one red alga as a nematicide.SOLUTION: There is provided a use of an aqueous liquid product obtained by extracting agar-containing red algae with an aqueous alkaline solution as a phytopathogenic nematode control agent. The extract product is in particular an aqueous phase obtained by extracting at least one species of red algae with an aqueous alkaline solution, followed by filtration to recover the aqueous phase, which can then be concentrated, dehydrated or freeze-dried and then redissolved in water for application.

Description

[Technical Field]

[0001] The present invention relates to the use of extracts of at least one red alga (Agarophytosis) for controlling plant parasitic nematodes, in particular root-knot nematodes. The present invention also relates to a method for controlling plant parasitic or plant pathogenic nematodes.

[0002] Plant-parasitic or plant-pathogenic nematodes are simple multicellular animals, usually consisting of about 1,000 cells. They are round, cylindrical, or spindle-shaped, bilaterally symmetrical, non-segmented worms, and are taxonomically distinct from earthworms, wireworms, and flatworms. Most nematodes are microscopic, ranging from 0.3 to 12 mm in body length and 0.01 to 0.5 mm in diameter, and are therefore typically observed under a microscope or magnifying glass.

[0003] Plant-parasitic or plant-pathogenic nematodes attack plants primarily through the roots: they drill holes in the plant with their stylets, inject digestive enzymes secreted from salivary glands into the plant tissue, and suck up the digestive products for delivery to the intestine. Symptoms of nematode infestation of plant root systems include galls, nodules, root lesions, excessive branching, stunted root development, and tip lesions. Root infection can also lead to a gradual wilting of the entire plant, resulting in death even in well-moistened soil.

[0004] To combat plant-parasitic or plant-pathogenic nematodes that reduce crop mass and yield, crop breeders can use nematode-resistant varieties or natural nematode predators or pathogens, a process known as biological control. It is possible to alternate crops that are susceptible to nematodes with non-host crops, but this can be difficult to achieve because some nematode species have a very wide host range, a technique known as cultural control. Synthetic nematicides, both fumigants and non-fumigants, are also generally very effective. However, the use of these products is gradually being banned because many have harmful side effects on human health and the environment. This is a chemical control method. In practice, these various methods are used in combination.

[0005] The Applicant Company has discovered that a specific extract from at least one species of red algae belonging to the Gelidiaceae family, such as Gelidium sesquipedale, which is a species that grows particularly well on the coasts of Morocco, has excellent nematicidal activity. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a graph showing the effect of the present invention. In the figure, "control" indicates the control group. [Figure 2] 1 is a photograph showing the effect of the present invention.

[0007] Therefore, a first object of the present invention is to use an aqueous liquid product obtained by extracting at least one species of red algae of the agarophyte family of the Gelidaceae family with an aqueous alkaline solution as an agent for controlling plant parasitic nematodes or plant pathogenic nematodes. In particular, the at least one agar-forming red alga may be selected from Gelidiella acerosa, Gelidium amansii, Gelidium cartilagineum, Gelidium liatulum, Gelidium pacificum, Gelidium lingulatam, Gelidium sesquipedale and Gelidium pristoides. In a particular embodiment, the extraction product is an aqueous phase obtained by extracting the at least one species of agaric red algae with an aqueous alkaline solution, followed by filtration to recover the aqueous phase, which can then be concentrated, dehydrated or freeze-dried and then redissolved in water for application. For example, the extraction is carried out at room temperature for 30 minutes to 8 hours, and the at least one species of red algae is extracted with 10 to 20 ml of the red algae. 3 It was used at a rate of 600 to 900 kg in an alkaline aqueous solution. Specifically, extraction was carried out using an alkaline aqueous solution containing 0.1 to 20% by weight, preferably 1 to 5% by weight, of sodium hydroxide or potassium hydroxide. The alkaline aqueous phase obtained after filtration may be neutralized with an acid. Specific acids include nitric acid, sulfuric acid, and phosphoric acid.

[0008] The aqueous liquid extract product of the present invention is applied by watering the plants to be protected or by adding, in particular by spraying, to the soil or substrate in which the plants to be protected grow. Another object of the present invention is a method for controlling plant parasitic or plant pathogenic nematodes, characterized in that the aqueous liquid extract product as defined above is applied to the soil or substrate in which the plants to be protected are planted or are intended to be planted.

[0009] The plants are selected in particular from horticultural, pasture and field crops such as market plants (tomatoes, melons, etc.), salad crops (lettuce, spinach, beans, etc.), fruit trees (banana trees, avocado trees, pear trees, apple trees, nectarine trees, etc.), ornamental plants, rose bushes, etc.

[0010] The aqueous liquid extraction product of the present invention is preferably applied diluted to 0.5 to 100 ml per 1000 L of water. The aqueous liquid extract product of the present invention can be applied at a rate of 1 to 10 liters per hectare. The aqueous liquid extract product of the present invention can be applied 1 to 7 times per week, specifically for 1 to 40 weeks.

[0011] The following examples are merely illustrative of the present invention and are not intended to limit the scope of the invention.

[0012] Examples 1-4: Preparation of extracts from Agar by alkaline treatment 800 kg of red algae (Gelidium sesquipedale) in 20 m 3 It was placed in water. The alkali treatment was carried out by adding NaOH at a concentration of 3% by mass at room temperature and stirring for 2 hours. It is then filtered through a 0.1 micron filter and passed through a 19m 3 The liquid portion was collected. This liquid product is called L1 (Example 1) and has a basic pH. This liquid product is neutralized with sulfuric acid to a pH of 7 and is called L1SL (Example 2). This liquid product is also neutralized with nitric acid and is called L1NL (Example 3). It is also neutralized with phosphoric acid and is called L1PL (Example 4).

[0013] Example 5: Procedure for diluting liquid products L1, L1SL, L1NL, L1PL L1, L1SL, L1NL, and L1PL (neutralized with phosphoric acid) were diluted to 0.01%, 0.1%, and 0.2% in the amounts shown in Table 1 below. The dilution was made with 10 liters of water, which corresponds to the capacity of the backpack sprayer used for application. [Table 1]

[0014] When diluted to 0.01% in 10 L of water: - The stock solution (concentrated starting solution) was homogenized by stirring for 5 minutes in case decantation occurred. - 10 liters of irrigation water pumped from a well was filled into the treatment device, and pH and conductivity were measured. 10 mL of the stock solution was added using a precision pipette and mixed before treatment. During the treatment, the solution was stirred before each application to ensure homogeneity.

[0015] Example 6: Nematode suppression effects of L1, L1SL, L1PL, and L1NL at different concentrations Ten comparative experiments were carried out with 20 lettuce plants each: four control plants sprayed with water, four lettuce plants sprayed with four concentrations of diluted L1, four lettuce plants sprayed with four concentrations of L1SL, four lettuce plants sprayed with four concentrations of L1PL, and four lettuce plants sprayed with four concentrations of L1NL. At each application, 40 mL of water or each aqueous liquid extract was applied to the top of each lettuce plant. Spraying was done once a week for four weeks. After 30 days, the treated lettuce plants were harvested and the number of galls present on the roots was counted.

[0016] The results are summarized in Table 2 below and shown diagrammatically in the accompanying Figure 1. All liquid products of the present invention have been shown to exhibit nematicidal activity at a dilution of 1 / 1000.

[0017] Fig. 2 in the accompanying drawings shows two lettuces: an untreated lettuce (left) and one (right) treated with 0.1% L1NL under the conditions described above, 30 days after treatment. Note that the black roots caused by nematode infection have disappeared in the treated lettuce. [Table 2-1] [Table 2-2] [Table 2-3]

Claims

1. 1. Use of an aqueous liquid product obtained by extracting at least one agar-like red algae belonging to the family Gelidaceae with an aqueous alkaline solution as an agent for controlling plant-parasitic (pathogenic) nematodes.

2. 2. The use according to claim 1, characterized in that the at least one agar-forming red algae is selected from Gelidiella acerosa, Gelidium amansii, Gelidium cartilagineum, Gelidium liatulum, Gelidium pacificum, Gelidium lingulatam, Gelidium sesquipedale and Gelidium pristoides.

3. 3. The use according to claim 1 or 2, characterized in that the extraction product is an aqueous phase obtained by extracting the at least one agaric red algae with an alkaline aqueous solution, followed by filtration to recover the aqueous phase, which is then concentrated, dehydrated, or freeze-dried, and then redissolved in water for application.

4. 4. The use according to claim 3, wherein the extraction is carried out at room temperature for 30 minutes to 8 hours, and the at least one red alga is extracted with 10 to 20 ml of aqueous alkaline solution. ３ Use characterized in that it is used at a rate of 600 to 900 kg.

5. 5. The use according to claim 3 or 4, characterized in that an alkaline aqueous solution containing 0.1 to 20% by weight, preferably 1 to 5% by weight, of sodium hydroxide or potassium hydroxide is used for extraction.

6. Use according to any one of claims 3 to 5, characterized in that the alkaline aqueous phase obtained after filtration has been neutralized with an acid, in particular with nitric acid, sulfuric acid or phosphoric acid.

7. 7. Use according to any one of claims 1 to 6, characterized in that the aqueous liquid extraction product is applied by spraying it on the plants to be protected or by being added, in particular by spraying it, to the soil or substrate on which the plants to be protected grow.

8. A method for controlling plant pathogenic nematodes, comprising applying an aqueous liquid extract product according to any one of claims 1 to 7 to the soil or substrate in which the plants to be protected are planted or in which the planting of the plants to be protected is planned.

9. 9. The method according to claim 8, characterized in that the plants are selected from commercial garden plants such as tomatoes, melons, etc., salad crops such as lettuce, spinach, beans, etc., fruit trees such as banana trees, avocado trees, pear trees, apple trees, nectarine trees, etc., ornamental plants, horticultural plants such as rose bushes, pasture plants, field crops.

10. 10. The method according to claim 8 or 9, characterized in that the aqueous liquid extraction product is applied at a dilution of 0.5 to 100 ml per 1000 L of water.

11. 11. The method according to any one of claims 8 to 10, characterized in that the aqueous liquid extraction product is applied at a rate of 1 to 10 liters per hectare.

12. 12. The method according to any one of claims 8 to 11, characterized in that the liquid extract product is applied 1 to 7 times per week, in particular for 1 to 40 weeks.

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