Essential oil composition for inhibiting pathogenic bacteria of chrysanthemum black spot

Abstract

The invention discloses an essential oil composition for inhibiting chrysanthemum black spot pathogenic bacteria. The essential oil used in the invention is a volatile oily mixture extracted from natural aromatic plants such as geranium and citronella, and has the advantages of being safe in source, free of toxic and side effects, effective and the like, and the geranium essential oil and the citronella essential oil are combined for use to achieve a synergistic effect, so that the inhibition effect of the essential oil on alternaria alternata is greatly improved; the essential oil composition disclosed by the invention is applied to prevention and control of the chrysanthemum black spot, can greatly reduce the safety problem and the drug resistance problem caused by chemical agents and the environmental pollution problem caused by pesticide residues, and is easy to popularize and apply.

Description

Technical Field

[0001] The invention belongs to the technical field of plant protection, and particularly relates to an essential oil composition for inhibiting pathogenic bacteria of chrysanthemum black spot disease. Background Art

[0002] Chrysanthemum (Chrysanthemum morifolium) belongs to the genus Chrysanthemum of the Asteraceae family. It is native to my country and is one of the top ten traditional famous flowers in my country and one of the four major cut flowers in the world. It has high ornamental and economic value. In addition, chrysanthemum is an important category in terms of food and medicinal functions in my country. It has the effects of dispersing wind and heat, detoxification, anti-inflammatory, antibacterial, and antioxidant. It is often used to treat wind-heat colds, headaches and dizziness, red and swollen eyes, blurred vision, sores, carbuncles, swellings, and other symptoms, and has high medicinal value.

[0003] Chrysanthemum production faces infection from a variety of fungal pathogens, which reduces or completely loses its yield, ornamental, medicinal or edible value, causing serious economic losses. Among them, black spot disease caused by Alternaria fungi infecting plant leaves is a widespread disease in chrysanthemum cultivation and production and transportation, with a large area of ​​damage and serious severity. Especially in the continuous cropping mode, pathogenic microorganisms in the soil multiply and explode in large numbers, which can easily lead to infection of plants or cuttings, and sometimes even threaten the entire production field.

[0004] At present, black spot disease is mainly controlled by spraying fungicides. The irrational and unscientific use of pesticides has brought many problems: the rise of drug resistance, the increase of pesticide residues, soil pollution and the destruction of environmental ecosystems, etc., threatening the production and ecosystem safety of local planting areas. Therefore, seeking safe, efficient and low-toxic biological agents is an important measure for green prevention and control. Plant essential oils are volatile oily mixtures with specific fragrances extracted from the flowers, leaves, stems, roots, fruits and seeds of aromatic plants in nature through different extraction methods, including alcohols, alkenes, esters, ketones and aldehydes. Many studies have shown that some plant essential oils can be used to antagonize pathogens, kill insects and mites, and kill nematodes. For example, lemon verbena, maple grass, white thorn branches and gray basil essential oils have antibacterial activity against anthracnose, stone fruit brown rot fungi, etc. Therefore, in-depth research on the mechanism of action of essential oils is of far-reaching significance for the development of more efficient, stable and specific green prevention and control products. Summary of the invention

[0005] In order to solve the problems of indiscriminate use of pesticides, abuse, residual pesticides, enhanced drug resistance, etc. in the current prevention and treatment of chrysanthemum black spot disease, the present invention provides an essential oil composition for inhibiting the pathogen of chrysanthemum black spot disease. The essential oils of geranium and citronella are used in combination, and the composition has an inhibitory effect on the pathogen of chrysanthemum black spot disease, Alternaria alternata, which is a fungal disease.

[0006] The first object of the present invention is to provide an essential oil composition for inhibiting Alternaria alternata, which consists of geranium essential oil and citronella essential oil.

[0007] Preferably, the essential oil composition consists of geranium essential oil and citronella essential oil in a volume ratio of 1:1.

[0008] The second object of the present invention is to provide a combined use of geranium essential oil and citronella essential oil in inhibiting Alternaria alternata.

[0009] The third object of the present invention is to provide a method for preventing and treating chrysanthemum black spot disease, comprising the step of using geranium essential oil and citronella essential oil in combination to inhibit alternaria.

[0010] The present invention has the following advantages:

[0011] The pathogen of chrysanthemum black spot disease, Alternaria alternata, is a fungus that can infect plants of various families and genera. It has strong adaptability and can harm hundreds of crops and horticultural plants. Alternaria alternata mainly infects leaves. After infection, multiple nearly circular or irregular dark brown spots appear on the lesions, which are very harmful.

[0012] The essential oil used in the present invention is a volatile oily mixture extracted from aromatic plants geranium and citronella in nature, and has the advantages of safe source, no toxic side effects, effectiveness, etc. The geranium essential oil and citronella essential oil are used together to achieve synergistic synergy, and the inhibitory effect of the essential oil on Alternaria alternata is greatly improved. The essential oil composition of the present invention is applied to the prevention and control of chrysanthemum black spot disease, which can greatly reduce the safety problems and drug resistance problems caused by chemical agents and the environmental pollution problems caused by pesticide residues, and is easy to promote and apply. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is the growth of Alternaria mycelium on different culture media; the sample marks on the figure are: CK corresponds to the bottom and front of the control culture medium, geranium corresponds to the bottom and front of the essential oil culture medium A, citronella corresponds to the bottom and front of the essential oil culture medium B, and geranium + citronella corresponds to the bottom and front of the essential oil culture medium C. DETAILED DESCRIPTION

[0014] The following examples are provided to further illustrate the present invention, rather than to limit the present invention.

[0015] The geranium essential oil stock solution was purchased from Guangzhou Yazhi Cosmetics Company, the product model is: geranium (special grade FA-025-2), and the purity is 100%; the citronella essential oil stock solution was purchased from Guangzhou Yazhi Cosmetics Company, the product model is: citronella (special grade FA-012), and the purity is 100%.

[0016] Example 1

[0017] 1. Preparation of culture medium

[0018] Control culture medium: Add tween80 with a final concentration of 0.1% by volume to the sterilized and slightly cooled but not yet solidified PDA culture medium solution, and make up to 50 mL with the PDA culture medium solution; then pour into a sterilized culture dish and solidify for later use.

[0019] Essential oil culture medium A: The geranium essential oil stock solution (mass fraction 100%) was diluted to 3200 times to obtain a geranium essential oil diluent, 15.62 μL of the geranium essential oil diluent was added to a PDA culture medium solution that had been sterilized and slightly cooled but not yet solidified, and then tween80 was added as a cosolvent with a final concentration of 0.1% by volume, and the volume was fixed to 50 mL with the PDA culture medium solution; then the solution was poured into a sterilized culture dish and solidified for standby use.

[0020] Essential oil culture medium B: The citronella essential oil stock solution (mass fraction 100%) was diluted to 3200 times to obtain a citronella essential oil diluent, 15.62 μL of the citronella essential oil diluent was added to a PDA culture medium solution that had been sterilized and slightly cooled but not yet solidified, and then tween80 was added as a cosolvent with a final concentration of 0.1% by volume, and the volume was fixed to 50 mL with the PDA culture medium solution; then the solution was poured into a sterilized culture dish and solidified for use.

[0021] Essential oil culture medium C: geranium essential oil stock solution (mass fraction 100%) is diluted to 3200 times to obtain geranium essential oil diluent, citronella essential oil stock solution (mass fraction 100%) is diluted to 3200 times to obtain citronella essential oil diluent, geranium essential oil diluent and citronella essential oil diluent are mixed in a volume ratio of 1: 1 to obtain an essential oil mixture, 15.62 μL of the essential oil mixture is added to a PDA culture medium solution that has been sterilized and slightly cooled but not yet solidified, and then tween80 is added with a final concentration of 0.1% by volume as a cosolvent, and the PDA culture medium solution is fixed to 50 mL; then poured into a sterilized culture dish, solidified for standby use.

[0022] 2. Preparation of Fungi for Assay

[0023] The Alternaria mycelium was inoculated on a common PDA culture medium in advance and cultured at 25°C for 6 days; then holes were punched using a borer (5 mm in diameter) to prepare an Alternaria cake.

[0024] 3. Experimental Methods

[0025] Use a sterilized inoculation stick to pick up a single Alternaria cake and inoculate it into the center of the control medium or essential oil medium A, B, and C. When inoculating, make sure that the mycelium side of the cake in each dish faces down. Seal the medium with sealing film and culture at 25℃ for 6 days.

[0026] After culturing at 25°C for 6 days, the colony diameter (reflecting the mycelial growth) was measured, and the inhibition rate of different culture media on the mycelial growth of Alternaria was calculated, inhibition rate (%) = (control colony diameter - treated colony diameter) / (control colony diameter - bacterial cake diameter).

[0027] King's formula was used to evaluate the combined effect of the two drugs. King's formula expression: q = E (A + B) / (EA + EB - EA * EB), where EA and EB represent the effects of components A and B when used alone, respectively; E (A + B) represents the effect of component A and component B used together. The q value is interpreted to evaluate whether the effect of the two components after combined use is better than when used alone. The significance of q value: less than 0.55 is obvious antagonism; greater than 0.55 and less than 0.85 is antagonism; between 0.85-1.15 is simple addition; greater than 1.15 and less than 20 is enhancement; greater than 20 is significant enhancement.

[0028] IV. Experimental Results

[0029] The results are shown in Table 1. Figure 1 As shown. The inhibition rate of 3200-fold diluted geranium essential oil (essential oil medium A) on the growth of Alternaria mycelium is 0.06, the inhibition rate of 3200-fold diluted citronella essential oil (essential oil medium B) on the growth of Alternaria mycelium is 0.24, and the inhibition rate of 3200-fold diluted geranium essential oil and 3200-fold diluted citronella essential oil combined (essential oil medium C) on the growth of Alternaria mycelium can reach 0.47; the q value calculated by King's formula is 1.60, that is, the inhibition rate effect of the combined use of the two essential oils is enhanced compared with the effect of geranium essential oil and citronella essential oil used alone, and has a significant synergistic effect.

[0030] Table 1 Inhibition of Alternaria growth by two essential oils diluted 3200 times and their mixture

[0031]

Claims

1. An essential oil composition for inhibiting Alternaria alternata, characterized in that: Composed of Geranium and Citronella essential oils.

2. The essential oil composition according to claim 1, characterized in that The essential oil composition consists of geranium essential oil and citronella essential oil in a volume ratio of 1:

1.

3. Application of geranium essential oil and citronella essential oil in combination to inhibit Alternaria alternata.

4. A method for preventing and treating chrysanthemum black spot disease, characterized in that: The invention comprises the steps of using geranium essential oil and citronella essential oil in combination for inhibiting alternaria.

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