Biological pesticide for preventing and treating cassava bacterial blight

Abstract

The present application belongs to the technical field of pesticides, and particularly relates to a kind of biological pesticide for preventing and treating cassava bacterial wilt, and the active ingredient thereof is compounded by copper acetylsalicylate and biological active ingredient, wherein the biological active ingredient is mesoxin or shenzai mycin.The biological pesticide of the present application uses the combination of copper acetylsalicylate and mesoxin or shenzai mycin as active ingredient, and the co-toxicity coefficient of the combination to the pathogen of cassava bacterial wilt is greater than 120 within a suitable mass ratio range, which shows significant synergistic effect.Compared with the use of single component, the combination can improve the prevention and treatment effect on cassava bacterial wilt, thereby helping to reduce the amount of pesticide per unit area, alleviate environmental pressure, save prevention and treatment cost, and meet the development needs of green agriculture.

Description

Technical Field

[0001] This invention belongs to the field of pesticide technology, specifically relating to a biological pesticide for controlling bacterial wilt disease of cassava. Background Technology

[0002] Cassava is an important starch, feed, and energy crop in tropical and subtropical regions. Bacterial wilt of cassava, also known as bacterial wilt or gummosis, can be caused by *Xanthomonas alopecuroides*, a pathogen that causes cassava wilt. Xanthomonas axonopodis pv. manihotis Bacterial wilt, caused by infection, is a significant bacterial disease affecting cassava production worldwide. It primarily infects the leaves, stems, and tubers of the cassava plant. Symptoms include leaf blight, chlorosis, pus discharge, and necrosis of the vascular bundles within the stem. In severe cases, the stem surface often shows depressions, and the leaves wilt at an accelerated rate. The vascular bundles of the affected tubers turn yellowish-brown, and the roots gradually dry out and rot, potentially leading to the death of the entire plant.

[0003] Control of bacterial wilt in cassava mainly relies on selecting healthy seed tubers, removing diseased plant debris, strengthening field management, rational crop rotation, and using copper-based fungicides and antibiotics. While these measures can reduce the severity of the disease to some extent, they still have some shortcomings in actual production: cassava is mostly propagated from seed tubers, and the pathogen can spread through infected seed tubers or diseased plant debris in the field. Relying solely on agricultural control measures is insufficient to stably control the spread of the disease under high disease pressure conditions. Furthermore, existing chemical agents are prone to fluctuations in efficacy and excessive dosage under long-term or single-use conditions, and some agents may also bring environmental stress and the risk of drug resistance.

[0004] Copper acetylsalicylate is a compound that combines the bactericidal activity of copper ions with the resistance-inducing properties of salicylic acid. Copper ions can inhibit plant pathogenic bacteria, while salicylic acid-related structures are closely related to plant defense responses. Therefore, copper acetylsalicylate has potential application in the control of bacterial plant diseases. Existing technology CN108450480B also discloses that copper acetylsalicylate has good control effects against bacterial angular leaf spot of cucumber, bacterial leaf spot of pepper, bacterial scab of pepper, and bacterial spot of tomato. However, when copper acetylsalicylate is used alone, its control effect on different pathogens may vary; simply increasing the concentration to improve efficacy may increase resistance, control costs, and the risk of copper accumulation. Therefore, it is necessary to improve its control efficiency against bacterial wilt of cassava and reduce the resistance risk of single active ingredients through compound formulation. Summary of the Invention

[0005] The purpose of this invention is to provide a biological pesticide for controlling bacterial wilt of cassava, so as to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A biological pesticide for controlling bacterial wilt of cassava, the active ingredient of which is a compound of copper acetylsalicylate and a bio-derived active ingredient, wherein the bio-derived active ingredient is kasugamycin or shenqinmycin.

[0007] Furthermore, the mass ratio of the copper acetylsalicylate to the streptomycin is 1:15-1.

[0008] Furthermore, the mass ratio of the copper acetylsalicylate to shenqinmycin is 1:40-1.

[0009] Furthermore, the bacterial wilt of cassava is caused by infection with the pathogenic species Xanthomonas cassavais.

[0010] Compared with the prior art, the present invention has the following beneficial effects: (1) The biological pesticide of the present invention uses a combination of copper acetylsalicylate and streptomycin or shenqinmycin as the active ingredient. The co-toxicity coefficient of the compound combination against the pathogen of bacterial wilt of cassava is greater than 120 within a suitable mass ratio range, showing a significant synergistic effect. Compared with the use of a single ingredient, it can improve the control effect of bacterial wilt of cassava, thereby helping to reduce the amount of pesticide used per unit area, reduce environmental pressure, save control costs, and meet the development needs of green agriculture.

[0011] (2) The biological pesticide of the present invention is composed of active ingredients with different mechanisms of action, which helps to reduce the sharing of drug resistance, delay the development of drug resistance in pathogens, and extend the service life of the agent. Detailed Implementation

[0012] The following is a clear and complete description of the technical solution of this invention patent. Obviously, the described embodiments are some, but not all, of the embodiments of this invention. Indoor activity test

[0013] 1. Test pathogens Carpet grass yellow single-celled cassava wilt disease species ( Xanthomonas axonopodis pv. manihotis ) 2. Culture medium YEB medium: 5g peptone, 1g yeast extract, 5g beef extract, 5g sucrose, 0.5g magnesium sulfate heptahydrate, 15g agar, add distilled water to a final volume of 1L, and adjust the pH to 7.2.

[0014] 3. Test reagents 99% Copper acetylsalicylate, 99% Zhongshengmycin, 95% Shenqinmycin Dissolve the tested agents and dilute them into a high-concentration single-agent stock solution with 0.1% Tween-80 aqueous solution. According to the results of the previous preliminary test, multiple ratio groups are set, and each single agent and each group of mixed agents are then diluted into 5 mass concentration gradients with 0.1% Tween-80 aqueous solution for later use.

[0015] 4. Test Method The Oxford cup method is used. The tested pathogen is cultured on YEB medium at 28°C for 48h. A single colony is picked and inoculated into 50mL of YEB liquid medium, and cultured with shaking at 28°C and 180r / min to the logarithmic growth phase, then centrifuged at 5000r / min for 10min. The bacterial cells are collected and resuspended in sterile water, and the OD is adjusted 600 value to 0.5 (about 1.0×10 8 CFU / mL). Pour 20mL of pre-melted YEB medium into a petri dish with a diameter of 9cm, and form a plate after cooling. Take 200μL of bacterial suspension and spread it evenly on the YEB plate. Place a 6mm Oxford cup in the center of the plate with forceps, one cup per dish. Add 200μL of the drug solution into the Oxford cup with a pipette, use the treatment with an equal amount of 0.1% Tween-80 aqueous solution added as the blank control, repeat each treatment 3 times, with 3 plates per repetition. After culturing in a 28°C bacterial incubator for 24h, observe and record the growth of the pathogen. Measure the diameter of the inhibition zone by the cross method, and calculate the colony growth inhibition rate.

[0016]

[0017] 4. Data Analysis Take the logarithm of the agent concentration as x and the corresponding probability value of the inhibition rate as y for linear regression analysis, to obtain the virulence regression equation and the EC 50 of each treated agent, and the Sun Yunpei method is used to calculate the co-toxicity coefficient (CTC value) of the mixture.

[0018] According to the classification standard for combined action: CTC≥120 indicates synergistic effect; CTC≤80 indicates antagonistic effect; 80<CTC<120 indicates additive effect. The results are shown in Table 1-2.

[0019] Table 1 Indoor bioactivity determination of the combination of copper acetylsalicylate and zhongshengmycin against Xanthomonas axonopodis pv. manihotis Copper acetylsalicylate 128.9901 100.0000 -- -- Bismuth subsalicylate 32.6279 395.3368 -- -- Copper acetylsalicylate 1: kasugamycin 15 27.8249 463.5779 376.8783 123.0047 Copper acetylsalicylate 1: kasugamycin 12 19.7810 652.0909 372.6186 175.0022 Copper acetylsalicylate 1: kasugamycin 9 25.6843 502.2138 365.8031 137.2907 Copper acetylsalicylate 1: kasugamycin 3 27.2956 472.5674 321.5026 146.9871 Copper acetylsalicylate 1: kasugamycin 1 31.6005 408.1901 247.6684 164.8131 It can be seen from Table 1 that after the effective components of copper acetylsalicylate and zhongshengmycin are combined, when the mass ratio is within the range of 1:15 to 1:1, the co-toxicity coefficients against Xanthomonas axonopodis pv. manihotis are all greater than 120, showing a synergistic effect.

[0020] Table 2. Indoor bioactivity assay of copper acetylsalicylate combined with shenzimidic acid against *Fusarium wilt*, the bacterial causal agent of cassava. Copper acetylsalicylate 128.9901 100.0000 -- -- Shenqinmycin 12.8356 1004.9402 -- -- Copper acetylsalicylate 1: Shenqinmycin 40 10.0470 1283.8668 982.8685 130.6245 Copper acetylsalicylate 1: Shenqinmycin 30 8.4088 1533.9894 975.7485 157.2115 Copper acetylsalicylate 1: Shenqinmycin 20 9.8340 1311.6748 961.8478 136.3703 Copper acetylsalicylate 1: Shenqinmycin 10 11.6209 1109.9837 922.6729 120.3009 Copper acetylsalicylate 1: Shenqinmycin 5 12.4333 1037.4567 854.1168 121.4654 Copper acetylsalicylate 1: Shenqinmycin 1 18.6291 692.4119 552.4701 125.3302 As shown in Table 2, the co-toxicity coefficients of the active ingredients copper acetylsalicylate and shenqinmycin, when combined in a mass ratio of 1:40-1, against the pathogenic species of cassava bacterial wilt, Xanthomonas caesarea, are all greater than 120, indicating a synergistic effect.

[0021] In summary, the biopesticide of this invention uses a combination of copper acetylsalicylate and streptomycin or shenqinmycin as its active ingredient. Within a suitable mass ratio range, the co-toxicity coefficient of the combination against the pathogen of bacterial wilt of cassava is greater than 120, demonstrating a significant synergistic effect. Compared with the use of a single ingredient, it can improve the control effect against bacterial wilt of cassava, thereby helping to reduce the amount of pesticide used per unit area, alleviate environmental pressure, save control costs, and meet the development needs of green agriculture.

Claims

1. A biological pesticide for controlling bacterial wilt disease of cassava, characterized in that, Its active ingredient is a compound of copper acetylsalicylate and a bio-derived active ingredient, wherein the bio-derived active ingredient is kasugamycin or shenqinmycin.

2. The biological pesticide for controlling bacterial wilt of cassava according to claim 1, characterized in that, The mass ratio of the copper acetylsalicylate compound to the kasugamycin is 1:15-1.

3. The biological pesticide for controlling bacterial wilt of cassava according to claim 1, characterized in that, The mass ratio of the copper acetylsalicylate to shenqinmycin is 1:40-1.

4. The biological pesticide for controlling bacterial wilt of cassava according to claim 1, characterized in that, The bacterial wilt disease of cassava is caused by infection with the pathogenic species Xanthomonas cassavais.