A comprehensive risk-benefit approach to rice sheath blight control

Abstract

This invention discloses a comprehensive risk-benefit optimization method for rice sheath blight control decisions. The method is as follows: 1. Obtain the sheath blight level in the area to be controlled; 2. Construct a pest and disease control decision optimization model; 3. Find the optimal solution of the objective function to obtain the optimal number of general application attempts (x1) and selective treatment attempts (x2); 4. Apply pesticides to the controlled area based on the number of general application attempts (x1) and selective treatment attempts (x2) obtained in step 3. This invention constructs an objective function that comprehensively considers control costs, benefit risks, and ecological risks. While considering control effectiveness and costs, it also focuses on control risks and ecological risks, providing optimal control decisions for rice sheath blight under different disease levels, thus offering optimal control decisions for rice sheath blight control.

Description

Technical Field

[0001] This invention belongs to the field of pest and disease control decision-making and agronomic technology, specifically relating to a method for controlling rice pests and diseases that integrates risk and benefit. Background Technology

[0002] Crop diseases are a significant cause of reduced grain production in my country and globally. With global climate change, the frequency of disease occurrence has been increasing in recent years, posing a serious threat to my country's food security. Currently, rice pests and diseases are mainly controlled through pesticide application, which often results in excessive pesticide use. This not only increases control costs but also easily causes agricultural environmental pollution and food safety issues, threatening sustainable agricultural development. Therefore, improving the scientific and rational use of pesticides is crucial for enhancing pest and disease control effectiveness, reducing ecological pollution, and ensuring food security, agricultural product quality, and ecological environmental safety. Currently, pest and disease control decisions rely heavily on human experience, primarily considering control effectiveness while neglecting control risks and ecological issues. This invention proposes a risk-benefit balanced decision-making method for rice sheath blight control, integrating control effectiveness, control costs, control risks, and ecological risks into the control decision-making process. An optimization model for rice sheath blight control decisions is established, providing optimal control decisions for integrated pest management of rice sheath blight. Summary of the Invention

[0003] The purpose of this invention is to provide a method for controlling rice sheath blight that balances risk and benefit. This method integrates control effectiveness, control risk, ecological risk, and control cost. It uses an optimization model to establish a decision optimization model for rice sheath blight control, which can provide the optimal control decision under different disease levels, thus providing a control decision method for integrated disease prevention and control.

[0004] A method for controlling rice sheath blight that integrates risk and benefit includes the following steps:

[0005] Step 1: Obtain the sheath blight level in the controlled area.

[0006] Step 2: Construct a decision optimization model for pest and disease control; The objective function f(x) of the decision optimization model for pest and disease control is shown in Equation (1); The objective is to minimize the objective function f(x).

[0007] f(x) = a + b + c Equation (1)

[0008] In equation (1), a represents the cost of prevention and control, as shown in equation (2); b represents the risk of returns, as shown in equation (3); and c represents the ecological risk.

[0009] a=S1·x1+S2·x2 Equation (2)

[0010] b = S3·x3 Equation (3)

[0011] In equations (2) and (3), x1 represents the number of general prevention and control applications; x2 represents the number of targeted treatments; x3 represents the prevention and control risk rate, as shown in equation (5); and x4 represents the application rate level. S1 represents the average cost per mu for one general prevention and control application; S2 represents the average cost per mu for one targeted treatment; and S3 represents the average purchase price of rice per mu.

[0012] x3=S-p1·x1-p2·x2 Equation (5)

[0013] In formula (5), p1 is the risk rate of reduced rice sheath blight after one general prevention; p2 is the risk rate of reduced rice sheath blight after one selective treatment; S is the yield loss rate; the yield loss rate S is determined according to the rice sheath blight grade; the higher the rice sheath blight grade, the greater the yield loss rate S.

[0014] Step 3: Find the optimal solution of the objective function to obtain the optimal number of general defenses x1 and the optimal number of attacks x2.

[0015] Step 4: Apply pesticides to the controlled area based on the general prevention number x1 and the treatment number x2 obtained in Step 3.

[0016] As a preferred option, when the sheath blight level is 0, 1, 2, 3, 4, 5, the yield loss rate S is 0.05, 0.1, 0.15, 0.25, 0.35, 0.45.

[0017] As a preferred option, the total amount of pesticide applied per mu is M = m1·x1 + m2·x2; m1 is the amount of pesticide applied per mu for one general prevention treatment; m2 is the amount of pesticide applied per mu for one selective treatment.

[0018] As a preferred option, the application rate level x4 has three possible values: 1, 2, and 3. When the total application rate per mu (M) is less than or equal to W1, x4 = 1; when the total application rate per mu (M) is in the range (W1, W2), x4 = 2; and when the total application rate per mu (M) is greater than W2, x4 = 3. W1 is the first application rate threshold per mu; W2 is the second application rate threshold per mu. The first application rate threshold per mu is the lower limit of the conventional empirical application rate; the second application rate threshold per mu is the upper limit of the conventional empirical application rate.

[0019] As a preferred option, the first average application rate threshold W1 = m1 + m2; the second average application rate threshold W2 = 3·(m1 + m2).

[0020] Preferably, the number of treatments x2 is limited to less than or equal to 3 times.

[0021] Preferably, the expression for the ecological risk c is shown in equation (4).

[0022] c = 10 x4-1 Equation (4)

[0023] In formula (4), x4 represents the application rate level. The application rate level x4 is determined based on the average total application rate M per mu; the larger the average total application rate M per mu, the larger the application rate level x4.

[0024] As a preferred option, the risk reduction rate p1 of one general prevention of sheath blight is 0.1; the risk reduction rate p2 of one treatment of sheath blight is 0.05.

[0025] As a preferred option, the average cost per mu (unit of land area) for general pest control is set at 11 yuan.

[0026] As a preferred option, the average cost per mu (unit of land area) for one treatment, S2, is set at 5.5 yuan; the average purchase price per mu (unit of land area) for rice, S3, is set at 1200 yuan.

[0027] The effective effects of this invention are:

[0028] This invention constructs an objective function that comprehensively considers control costs, profit risks, and ecological risks. While considering control effectiveness and costs, it also focuses on control risks and ecological risks, providing the optimal number of pesticide applications for rice sheath blight at different disease levels, thereby minimizing the losses caused by rice sheath blight. Attached Figure Description

[0029] Figure 1 This is a technical roadmap for making prevention and control decisions in this invention. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings.

[0031] like Figure 1 As shown, a method for controlling rice sheath blight that integrates risk and benefit includes the following steps:

[0032] Step 1: Construct a pest and disease control decision optimization model and set control decision variables; The decision variables involved in the pest and disease control decision optimization model include the number of general prevention and control measures, the number of targeted treatments, the control risk rate, and the ecological risk.

[0033] 1.1 The control of rice sheath blight adopts a combination of general prevention and selective treatment. Therefore, the decision variables include the number of general prevention x1 and the number of selective treatment x2.

[0034] 1.2 To quantify the control effects of different control schemes on diseases, a control risk rate x3 is introduced, which represents the risk rate after control under different schemes.

[0035] 1.3 To quantify ecological risks, a pesticide application level x4 is introduced.

[0036] Step 2: Set the objective function f(x) for decision optimization as shown in Equation (1); with the objective function f(x) being minimized as the goal.

[0037] f(x) = a + b + c Equation (1)

[0038] Among them, dimensionless calculations are performed between a, b, and c; a represents the prevention and control cost, including the cost of aerial spraying services and the cost of pesticides used for prevention and control, and its expression is shown in equation (2); b represents the benefit risk, that is, the economic loss caused by the optimal prevention and control decision, and its expression is shown in equation (3); c represents the ecological risk, that is, the ecological risk caused by the total amount of pesticides applied per mu under the optimal prevention and control decision, and its expression is shown in equation (4).

[0039] a=S1·x1+S2·x2 Equation (2)

[0040] b = S3·x3 Equation (3)

[0041] c = 10 x4-1 Equation (4)

[0042] Wherein, S1 is the average cost per mu for general pest control; S2 is the average cost per mu for selective treatment, in this embodiment; S3 is the average purchase price of rice per mu, which is set to 1200 in this embodiment.

[0043] According to the investigation, the average cost of aerial spraying for general prevention of rice sheath blight is 8 yuan per mu, and the average cost of aerial spraying for selective treatment is 4 yuan per mu. The average cost of pesticides for general prevention is 3 yuan per mu, and the average cost of pesticides for selective treatment is 1.5 yuan per mu. The average purchase price of rice per mu is 1200 yuan. Therefore, in this embodiment, the average cost per mu for general prevention is set to 11 yuan, and the average cost per mu for selective treatment is set to 5.5 yuan.

[0044] Step 3: Constraints

[0045] 3.1 The prevention and control risk rate x3 is shown in equation (5).

[0046] x3=S-p1·x1-p2·x2 Equation (5)

[0047] Where S is the yield reduction loss rate; p1 is the risk rate of reduction after one general prevention of sheath blight; p2 is the risk rate of reduction after one selective treatment of sheath blight; in this embodiment, the risk rate of reduction after one general prevention of sheath blight is set to 0.1 and the risk rate of reduction after one selective treatment of sheath blight is set to 0.05 based on the investigation.

[0048] The yield loss rate S is determined based on the severity of rice sheath blight; the higher the severity of rice sheath blight, the greater the yield loss rate S. In this embodiment, the yield loss rate S under different severity levels of rice sheath blight is set based on the agricultural industry standard "Calculation Criteria for Natural Damage Loss Rate of Major Crop Diseases and Pests" (NY / T 3301-2018) and combined with the actual needs of disease and pest control, as shown in Table 2. The severity level of rice sheath blight can be the prediction result of a crop disease and pest remote sensing monitoring and prediction system, the result of a regional-scale disease prediction and early warning model, the suitability of the disease habitat, or the disease severity level predicted by professional plant protection personnel based on historical disease conditions, environment, and plant protection experience.

[0049] Table 2. Yield loss rate under different rice sheath blight severity levels

[0050] Sheath blight level Production reduction loss rate S 0 0.05 1 0.1 2 0.15 3 0.25 4 0.35 5 0.45

[0051] 3.2 The definition of the application rate level x4 is shown in Table 3:

[0052] Table 3 Definitions of Application Dosage Grades

[0053] <![CDATA[Dosage level x4]]> Total pesticide application rate per mu (M(g)) Level 1 No more than 7 Level 2 8-21 Level 3 Greater than 21

[0054] Wherein, the total amount of pesticide applied per mu is M = m1·x1 + m2·x2; m1 is the amount of pesticide applied per mu for one general prevention treatment; m2 is the amount of pesticide applied per mu for one targeted treatment. In this embodiment, m1 is 5g; m2 is 2g.

[0055] 3.3 Number of treatments x2 should not exceed 3 times.

[0056] 3.4 When the risk prevention rate is less than 0, the risk of return b equals 0.

[0057] Step 4: Based on the objective function and constraints constructed in Steps 1 to 3, seek the optimal solution. Solve equations (1), (2), (3), (4), (5) and other constraints simultaneously to obtain the number of general prevention attempts x1 and the number of treatment attempts x2 under different sheath blight levels, which will serve as the optimal prevention and control decision.

[0058] Step 5: Apply pesticide once for general prevention and twice for targeted treatment in areas affected by rice sheath blight to complete the control of rice sheath blight.

[0059] This embodiment obtains the optimal number of general prevention attempts (x1), the number of targeted treatments (x2), the control risk rate (x3), the pesticide application rate level (x4), and the minimum value of the objective function (f(x)) for different levels of sheath blight. min The values ​​are shown in Table 4 below.

[0060] Table 4. Optimal control decisions for different disease severity levels

[0061]

[0062] The above-mentioned optimal control decision model for sheath blight can minimize risks and maximize benefits while taking into account both risks and benefits, thus providing the optimal control decision for pest and disease control.

Claims

1. A method for controlling rice sheath blight that integrates risk and benefit, characterized in that: Includes the following steps: Step 1: Obtain the sheath blight level in the controlled area; Step 2: Constructing a pest and disease control decision optimization model; the objective function of the pest and disease control decision optimization model. f ( x 1, x 2, x 3, x 4) As shown in equation (1); with the objective function f ( x 1, x 2, x 3, x 4) Minimize as the objective; f ( x 1, x 2, x 3, x 4) = a + b + c Equation (1) In equation (1), a represents the cost of prevention and control, and its expression is shown in equation (2). b represents risk cost, and its expression is shown in equation (3); c represents ecological risk; a = S1·x1 + S2·x2 Equation (2) b = S3·x3 Equation (3) In equations (2) and (3), x1 represents the number of general prevention and control measures; x2 represents the number of targeted treatments; x3 represents the prevention and control risk rate, the expression of which is shown in equation (5); x4 represents the application rate level; S1 represents the average cost per mu for one general prevention and control measure; S2 represents the average cost per mu for one targeted treatment; and S3 represents the average purchase price per mu of rice. The expression for the ecological risk c is shown in equation (4); c=10 x4-1 Equation (4) In formula (4), x4 is the application rate level; the application rate level x4 is determined based on the average total application rate M per mu; the larger the average total application rate M per mu, the larger the application rate level x4. x3 = S-p1·x1-p2·x2 Equation (5) In formula (5), p1 is the risk rate of reduced rice sheath blight after one general prevention; p2 is the risk rate of reduced rice sheath blight after one selective treatment; S is the yield loss rate; the yield loss rate S is determined according to the rice sheath blight grade; the higher the rice sheath blight grade, the greater the yield loss rate S. Step 3: Find the optimal solution to the objective function to obtain the optimal number of general defense attempts x1 and the optimal number of attack attempts x2; Step 4: Apply pesticides to the controlled area based on the general prevention number x1 and the treatment number x2 obtained in Step 3.

2. The method for controlling rice sheath blight according to claim 1, characterized in that: When the sheath blight severity level is 0, 1, 2, 3, 4, 5, the yield loss rate S is 0.05, 0.1, 0.15, 0.25, 0.35, 0.45, respectively.

3. The method for controlling rice sheath blight according to claim 1, characterized in that: The average total amount of pesticide applied per mu is M = m1·x1 + m2·x2; m1 is the average amount of pesticide applied per mu for general prevention once; m2 is the average amount of pesticide applied per mu for selective treatment once.

4. The method for controlling rice sheath blight according to claim 1, characterized in that: The application rate level x4 has three values: 1, 2, and 3. When the total application rate per mu M is less than or equal to W1, x4=1; when the total application rate per mu M is (W1, W2], x4=2; when the total application rate per mu M is greater than W2, x4=3; W1 is the first application rate threshold per mu; W2 is the second application rate threshold per mu.

5. The method for controlling rice sheath blight according to claim 1, characterized in that: The first threshold for average pesticide application rate per mu is W1 = m1 + m2; the second threshold for average pesticide application rate per mu is W2 = 3·(m1 + m2).

6. The method for controlling rice sheath blight according to claim 1, characterized in that: The number of treatments x2 is limited to less than or equal to 3 times.

7. The method for controlling rice sheath blight according to claim 1, characterized in that: The risk reduction rate p1 for one general prevention of sheath blight is 0.1; the risk reduction rate p2 for one treatment of sheath blight is 0.05.

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