A pesticide composition for preventing and controlling papaya downy mildew

Abstract

The present invention belongs to the technical field of downy blight control, and specifically relates to a pesticide composition for controlling papaya downy blight. A pesticide composition, the pesticide composition is used to control papaya downy blight, and the activity of the pesticide composition is compounded by valeramide and chloroindole hydrazide or pyraclostrobin; wherein the mass ratio of valeramide to chloroindole hydrazide is 1‑25:15‑1; the mass ratio of valeramide to pyraclostrobin is 1‑40:8‑1. The compounding of valeramide with chloroindole hydrazide or pyraclostrobin of the present invention can improve the control effect of papaya downy blight, reduce the application amount of the agent, help improve the risk of drug resistance and the problem of pesticide residues, and is of great significance for the development of new pesticides to control papaya downy blight.

Description

Technical Field

[0001] The invention belongs to the technical field of downy blight prevention and control, and particularly relates to a pesticide composition for preventing and controlling downy blight on papaya. Background Art

[0002] Papaya is an evergreen softwood small tree of the genus Carica of the family Caricaceae. It is native to southern Mexico and the adjacent Central America region. It is widely planted in Taiwan, Guangdong, Guangxi and Yunnan provinces in my country. In Guangxi, except for the high-altitude mountainous areas in northern Guangxi, where the temperature is low and the frost period is long, papaya can be planted in other areas. At present, the demand for papain in the market is increasing, which has promoted the expansion of papaya cultivation area to a certain extent.

[0003] During the papaya planting process, it is inevitable that it will be harmed by diseases and pests, such as papaya ringspot mosaic, papaya anthracnose, papaya gray-brown spot, papaya powdery mildew, papaya frost and papaya root rot, etc. Among them, papaya frost harms seedlings, with brown, irregular, water-soaked leaf spots, and white frost on the back when wet; the stems become dark brown, water-soaked and rotten, with white frost on the surface.

[0004] Chemical agents are a common and convenient means of preventing and controlling papaya frost blight, but the long-term use of a single chemical agent can easily lead to problems such as pesticide resistance, pesticide residues and environmental pollution. Therefore, it is of great significance to develop new pesticides to prevent and control papaya frost blight. Summary of the invention

[0005] The object of the present invention is to provide a pesticide composition for preventing and controlling papaya downy blight, so as to solve the problem of long-term use of a single chemical agent in the background art.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A pesticide composition, which is used for preventing and treating papaya downy blight, wherein the activity of the pesticide composition is formed by compounding valerian with chlorindole hydrazide or pyraclostrobin; wherein:

[0008] The mass ratio of valerianide to chloroindole hydrazide is 1-25:15-1;

[0009] The mass ratio of valerianide to pyraclostrobin is 1-40:8-1.

[0010] The effect is better, and the mass ratio of the valerianthamine to the chloroindole hydrazide is 1:7.

[0011] More specifically, the pathogen of papaya downy mildew is litchi downy mildew (Peronphthora litchiChen ex Ko et al.).

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] The effective inhibition median concentrations of valeramide, chloroindole hydrazide and pyraclostrobin on the germination of litchi downy mildew spores are 5.539 mg / L, 13.159 mg / L and 2.672 mg / L respectively. When compounded, the effective inhibition median concentration of valeramide and chloroindole hydrazide on the germination of litchi downy mildew spores is within the range of 122.703-337.689 in the mass ratio of 1-25:15-1, and the co-toxicity coefficient is greater than 120, showing a synergistic effect; the effective inhibition median concentration of valeramide and pyraclostrobin on the germination of litchi downy mildew spores is within the range of 120.851-171.210 in the mass ratio of valeramide and pyraclostrobin is greater than 120, showing a synergistic effect. It is shown that the compounding of valeramide with chloroindole hydrazide or pyraclostrobin can improve the control effect on papaya downy mildew, reduce the application amount of the agent, help to improve the risk of drug resistance and the problem of pesticide residues, and is of great significance for the development of new pesticides to control papaya downy mildew. DETAILED DESCRIPTION

[0014] 1. Test strains

[0015] Peronphthora litchi Chen ex Ko et al., isolated from infected papaya plants.

[0016] 2. Test reagents

[0017] 98% valeramide technical, 98% chloroindole hydrazide technical, 92% pyraclostrobin technical, all of the above agents come from the laboratory of Guangxi Zhuang Autonomous Region Subtropical Crops Research Institute.

[0018] After the test drug is dissolved, it is diluted with 0.1% Tween-80 aqueous solution to form a single-dose stock solution, and multiple groups of proportions are set. Each single dose and proportioned mixture is set with 5 mass concentration gradients according to the equal ratio method.

[0019] 3. Test culture medium

[0020] Lima bean culture medium: add 60g lima bean powder to 800mL water, heat at 60℃ for 1h, filter and collect juice; add 15g agar powder, heat and melt, and add water to make up to 1000mL.

[0021] 4. Test method (refer to "NY / T 1156.1-2006 Pesticide Indoor Bioassay Test Guidelines Fungicides Part 1: Inhibition of Pathogenic Fungal Spore Germination Test Concave Slide Method")

[0022] The test strain Peronophytum litchii was cultured on lima bean medium until spores were produced. The spores were washed with sterile water and filtered through four layers of filter paper. The concentration of the spore suspension was adjusted to 2.0 × 10 5 / mL. Take 0.5mL of the drug solution and 0.5mL of the spore suspension, mix them evenly, use a micropipette to draw the mixed solution and drop it onto a concave glass slide, put it into a moisturizing box, and place it in a 28℃ incubator. Set up 5 replicates for each treatment, and set the treatment of 0.1% Tween-80 aqueous solution as a blank control.

[0023] When the spore germination rate of the blank control reaches more than 85%, the spore germination is checked and processed. Three fields of view are randomly observed in each treatment and each repetition, and a total of 200 spores are investigated. The number of germination and the total number of spores are recorded respectively. The spore germ tube length greater than the short radius of the spore is considered to be germinated. Based on the survey data, the relative inhibition rate of spore germination of each treatment is calculated.

[0024]

[0025] 5. Data Analysis

[0026] Calculate the toxicity regression equation of the drug Y = ax + b, and obtain the effective inhibitory concentration EC of the drug on the target pathogen. 50 The co-toxicity coefficient (CTC) was calculated according to the Sun Yunpei method.

[0027] 6. Test results

[0028] The synergistic effect of the drug was evaluated based on the calculated co-toxicity coefficient (CTC), CTC≤80 was antagonistic, 80<CTC<120 was additive, and CTC≥120 was synergistic. The results are shown in Table 1-3.

[0029] Table 1 The results of toxicity test of single agent of valerian, chlorindole hydrazide and pyraclostrobin against litchi downy mildew

[0030]

[0031] As shown in Table 1, the effective inhibitory concentrations of valerianide, chlorindole hydrazide and pyraclostrobin on the spore germination of litchi downy mildew were 5.539 mg / L, 13.159 mg / L and 2.672 mg / L, respectively.

[0032] Table 2 The results of toxicity test of valeramide and chloroindole hydrazide against litchi downy mildew

[0033]

[0034] As shown in Table 2, when valerianide and chloroindole hydrazide are compounded, within the mass ratio range of 1-25:15-1, the effective inhibition concentration on the spore germination of litchi downy mildew is within 122.703-337.689, and the co-toxicity coefficient is greater than 120, showing a synergistic effect.

[0035] Table 3 The results of toxicity test of valeramide and pyraclostrobin against litchi downy mildew

[0036]

[0037] As shown in Table 3, when valerianide and pyraclostrobin are combined, within the mass ratio range of 1-40:8-1, the effective inhibition concentration on the spore germination of litchi downy mildew is within the range of 120.851-171.210, and the co-toxicity coefficient is greater than 120, showing a synergistic effect.

[0038] In summary, the compounding of valerianide with chlorindole hydrazide or pyraclostrobin can improve the control effect on papaya downy mildew, reduce the application amount of the agent, help improve the risk of drug resistance and the problem of pesticide residues, and is of great significance for the development of new pesticides to control papaya downy mildew.

Claims

1. A pesticide composition for preventing and treating papaya downy blight, characterized in that: The activity of the pesticide composition is formed by compounding valerian with chlorindole hydrazide or pyraclostrobin; wherein, The mass ratio of valerianide to chloroindole hydrazide is 1-25:15-1; The mass ratio of valerianide to pyraclostrobin is 1-40:8-1.

2. The pesticide composition according to claim 1, characterized in that The mass ratio of valerianthamine to chloroindole hydrazide is 1:

7.

3. The pesticide composition according to claim 1, characterized in that The pathogen of papaya downy blight is litchi downy mildew (Peronphthora litchi Chen ex Ko et al.).

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