A biological pesticide for preventing and controlling avocado root rot

Abstract

The present invention belongs to the technical field of biopesticides, and specifically relates to a biopesticide for controlling avocado root rot. The biopesticide for controlling avocado root rot comprises a binary compound of lentinan and osthole, thymol, or hydratin. When lentinan is compounded with osthole, thymol, or hydratin at a certain mass ratio, the compound exhibits a synergistic effect in inhibiting the growth of avocado root rot bacteria. Compared to single active ingredients, the compound improves the control efficacy of avocado root rot, reduces pesticide usage, and lowers control costs.

Description

Technical Field

[0001] The invention belongs to the technical field of biological pesticides, and particularly relates to a biological pesticide for preventing and treating avocado root rot. Background Art

[0002] Avocado, also known as alligator, avocado, avocado, and camphor pear, belongs to the genus Alligator of the Lauraceae family and is mainly distributed in Guangdong, Guangxi, Fujian, and Yunnan. Avocado fruit is rich in nutrients and has a good flavor. It is a high-energy, low-sugar fruit that can be used as a health food for people with diabetes. Root rot caused by Phytophthora cinnamomi is one of the major diseases that restrict the rapid development of the avocado industry. When avocado root rot occurs, the leaves of the aboveground part turn from green to light yellow to yellow. Then, the leaves of the affected plants fall off in large numbers, and the crown becomes sparse. In the later stages, all the leaves of the affected plants dry up and fall off in large numbers. The underground part starts to become infected from the root tip. In the early stage of the disease, the root tip turns light brown to black and is very easy to break. The disease gradually spreads from the root tip to the lateral roots, main root, and stem base, causing the roots and stem base to gradually turn black. As the disease progresses, the diseased roots rot.

[0003] In agriculture, avocado root rot can be controlled using pesticides such as metalaxyl-M, dimethomorph, and fludioxonil. However, long-term use of these pesticides can easily lead to the development of resistance in pathogens, reducing their effectiveness. However, combining different pesticides and screening for synergistic combinations can both improve efficacy and slow the development of resistance. Therefore, identifying synergistic combinations against avocado root rot is of great significance.

[0004] Lentinan is an effective active ingredient extracted from high-quality shiitake mushroom fruiting bodies and is an immunopotentiator. Clinical and pharmacological studies have shown that lentinan has antiviral, antitumor, immune function regulation and interferon stimulation effects. Patent application number CN201810494636.4 discloses a bactericidal composition containing prothioconazole and its application, and specifically discloses that when prothioconazole and lentinan are compounded in a certain mass ratio, they have a synergistic effect on rice sheath blight. Patent application number CN201210280700.1 discloses a bactericidal composition containing prochloraz and lentinan and its application, and specifically discloses that the combination of prochloraz and lentinan has a good preventive and control effect on various fungal diseases such as sheath blight, rice blast, rice false smut, leaf blight, rust, powdery mildew, brown spot, damping-off and gray mold.

[0005] The inventors discovered through laboratory experiments that when Lentinan is combined with osthole, thymol, or hydratin at a certain mass ratio, it has a synergistic effect against avocado root rot bacteria. Currently, there are no reports on the combination of Lentinan with osthole, thymol, or hydratin.

[0006] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0007] The purpose of the present invention is to provide a biological pesticide for preventing and treating avocado root rot, which can improve the prevention and treatment effect of avocado root rot compared with a single active ingredient and can also delay the development of drug resistance of pathogens.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A biological pesticide for preventing and treating avocado root rot, the active ingredient of which is a binary compound of lentinan and osthole, thymol or hydramycin.

[0010] Preferably, the mass ratio of lentinan to osthole is 1-19:8-1.

[0011] Preferably, the mass ratio of lentinan to thymol is 1-30:10-1.

[0012] As a preference, the mass ratio of Lentinan to Hydrate is 1-20:40-1

[0013] Specifically, the avocado root rot pathogen is Phytophthora cinnamomi.

[0014] The present invention also provides a biopesticide preparation, which includes the biopesticide for preventing and controlling avocado root rot.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) When Lentinan is compounded with osthole, thymol or hydrated mycobacterium in a certain mass ratio, the present invention has a synergistic effect on inhibiting the growth of avocado root rot bacteria. Compared with a single active ingredient, it can improve the prevention and control effect of avocado root rot, reduce the use of pesticides, and reduce the cost of prevention and control.

[0017] (2) The present invention can delay the development of drug resistance in pathogens and reduce the risk of drug resistance compared with a single agent.

[0018] (3) The biological pesticide for preventing and treating avocado root rot of the present invention is green and safe. DETAILED DESCRIPTION

[0019] The following is a clear and complete description of the technical solution of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of the present invention.

[0020] Example :Screening of control agents

[0021] 1. Test strains

[0022] Diseased lateral roots with typical symptoms of avocado root rot were selected, and the pathogen was isolated and purified by tissue separation in the laboratory. It was identified as Phytophthora cinnamomi and propagated on PDA medium at 28℃ in the dark.

[0023] 2. Test agents

[0024] 99% Lentinan technical, 99% Osthole technical, 98% Thymol technical, 98% Hydrateomycin technical, all of the above agents are commercially available.

[0025] After the test agent is dissolved, it is diluted with 0.1% Tween-80 aqueous solution to a single-dose stock solution of 5000 mg / L. Multiple groups of proportions are set up, and each single-dose stock solution and proportioned mixture are set to 5 mass concentration gradients according to the equal ratio method.

[0026] 3. Test methods

[0027] The hyphal growth rate method was used. 9 mL of pre-melted PDA medium and 1 mL of drug solution were mixed evenly and poured into a 9 cm diameter Petri dish. After cooling, the drug-containing plates were formed. A 0.1% Tween-80 aqueous solution was used as a blank control. Five replicates were set for each drug concentration. A 5 mm diameter borer was used to cut a bacterial cake from the edge of the test strain colony. This cake was inoculated onto the center of the drug-containing plate and the blank control plate. The plates were covered and incubated in the dark at 28°C for 4 days. The colony diameters were measured using the cross-hatch method, and the inhibition rate of hyphal growth by the different treatments was calculated.

[0028]

[0029] 4. Data Analysis

[0030] DPS software was used for data statistical analysis. The logarithmic value of fungicide concentration was taken as x and the corresponding probability value of mycelial growth inhibition rate was taken as y for linear regression. The virulence regression equation and the virulence EC value of the agent to the target pathogen were obtained. 50 The co-toxicity coefficient (CTC) was calculated according to the Sun Yunpei method.

[0031] 5. Measurement results

[0032] The synergistic effect of the agents was evaluated based on the calculated co-toxicity coefficient (CTC). CTC ≤ 80 indicated an antagonistic effect, 80 < CTC < 120 indicated an additive effect, and CTC ≥ 120 indicated a synergistic effect. The results are shown in Tables 1-3.

[0033] Table 1 The results of toxicity test of Lentinan and Osthole complex against avocado root rot pathogen

[0034]

[0035] As shown in Table 1, after Lentinan and osthole were compounded, the co-toxicity coefficient against avocado root rot pathogens was greater than 120 within the mass ratio of 1-19:8-1, showing a synergistic effect.

[0036] Table 2 Results of toxicity test of Lentinan and thymol complex against avocado root rot pathogen

[0037]

[0038]

[0039] As shown in Table 2, after Lentinan and thymol were compounded, the co-toxicity coefficient against avocado root rot pathogens was greater than 120 within the mass ratio of 1-30:10-1, showing a synergistic effect.

[0040] Table 3 Results of toxicity test of Lentinan and Hydracopycin complex against avocado root rot pathogen

[0041]

[0042] As shown in Table 3, after Lentinan and Hydraconazole were compounded, the co-toxicity coefficient against avocado root rot pathogens was greater than 120 within the mass ratio of 1-20:40-1, showing a synergistic effect.

[0043] In summary, when Lentinan is compounded with osthole, thymol or hydratin in a certain mass ratio, it has a synergistic effect on inhibiting the growth of avocado root rot bacteria. Compared with a single active ingredient, it can improve the prevention and control effect of avocado root rot, reduce the use of pesticides, and reduce the cost of prevention and control.

[0044] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A biological pesticide for preventing and treating avocado root rot, characterized in that: Its active ingredients are composed of a binary combination of Lentinan and Osthole; The mass ratio of lentinan to osthole is 1-19:8-1.

2. The biological pesticide for preventing and treating avocado root rot according to claim 1, characterized in that The avocado root rot pathogen is Phytophthora cinnamomi.

3. A biopesticide preparation, characterized in that: The biopesticide preparation includes the biopesticide for preventing and controlling avocado root rot according to claim 1.

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