1.1 Problem

Bacterial wilt is a devastating bacterial plant disease caused by Ralstonia solanacearum. It is characterized by fast spread, a wide host range, and high difficulty in control, mainly harming various cash crops such as those in the Solanaceae, Fabaceae, and Brassicaceae families. Its typical symptoms include sudden wilting of the above-ground parts of crops; leaves remain green but lose luster; roots turn brown and rot; when the stem is cut, browned vascular bundles are visible, and white bacterial ooze exudes when squeezed. If the disease is not controlled in time after onset, the plants usually die within 1–2 weeks, causing a fatal blow to crop yield.

Ralstonia solanacearum was first discovered by American plant pathologist Erwin Smith in the late 19th century and was named Pseudomonas solanacearum. Later, through molecular biology research, it was reclassified into the genus Ralstonia. This bacterium has a rod-shaped cell morphology; it loses motility at 36°C and regains it at 38°C. It causes wilt diseases by invading the xylem vessels of plants and can infect more than 300 plant species in 44 families, with particularly severe damage to Solanaceae crops such as tomatoes and potatoes.

Studies have found that its pathogenic mechanism is related to the inhibition of host protein phosphatases by the type III effector protein RipAS. Meanwhile, the temperature-sensitive gene yqhE affects pathogenicity by regulating vitamin C synthesis. Using GFP gene labeling technology, it has been confirmed that the bacterium maintains stable infectivity in the host, and low-temperature anaerobic soil disinfection combined with Bacillus strains can significantly improve the prevention and control effect.

Practical Cases in China

From the perspective of practical agricultural cases, the harm of bacterial wilt has spread to many major production areas in China.

At a tomato planting base in Chengdu, Sichuan, due to high-temperature and high-humidity weather in the summer of 2024, bacterial wilt broke out intensively. Li Jianguo, a local farmer, had 4.2 mu (≈0.28 hectares) of his 5-mu tomato field affected. The infected plants wilted in contiguous patches in a short period, and finally, he harvested less than one-fifth of the normal yield, with a loss of over 30,000 RMB.

A similar situation exists in the pepper-producing area of Zhanjiang, Guangdong: the incidence rate of bacterial wilt in local plots with perennial pepper cultivation has risen from 15% in 2019 to 40% in 2024. In some plots with continuous cropping for more than five years, almost no harvest was obtained after the disease occurred, and many farmers gave up traditional pepper cultivation due to the disease.

National Data and Agricultural Impact

According to the 2024 Crop Disease Monitoring Report of the Ministry of Agriculture and Rural Affairs, the annual occurrence area of bacterial wilt in China exceeds 12 million mu (≈800,000 hectares), involving more than 20 major crops such as tomatoes, potatoes, and tobacco.

Among them:

• The average incidence rate in tomato-producing areas reaches 35%, and the severe incidence rate exceeds 80%, leading to an annual reduction of about 2.8 million tons in national tomato production and a direct economic loss of over 6 billion RMB.
• In major potato-producing areas, the annual yield reduction due to bacterial wilt ranges from 15% to 20%, reducing the supply of commercial potatoes by about 1.2 million tons each year.

More seriously, Ralstonia solanacearum can survive in soil for 5–8 years. With the popularization of continuous cropping models in protected agriculture, the annual incidence area of bacterial wilt in China has increased by 12% over the past five years, and it has become one of the main diseases restricting the stable production of vegetables and cash crops.

1.2 Existing solutions

Currently, the prevention and control of bacterial wilt still face many bottlenecks.

• Chemical agents are difficult to completely eliminate pathogens in the soil and are likely to cause environmental pollution.
• The breeding cycle of disease-resistant varieties is long, and there are few varieties adaptable to different production areas.
• Agricultural control measures (such as crop rotation) are restricted by land resources, making large-scale promotion difficult.

Therefore, the development of green prevention and control technologies, the cultivation of resistant crop varieties, and the construction of an integrated prevention and control system for bacterial wilt have become urgent priorities.

This issue is not only closely related to farmers’ economic benefits but is also of great importance to ensuring the stable supply of agricultural products in China.

1.3 Our Ideas

Since the existing bacterial wilt prevention systems are imperfect and incomplete, our team aims to build an integrated bacterial wilt control system that can minimize negative environmental impacts while improving detection accuracy and treatment efficiency.

Our goal is to establish a sustainable and environmentally friendly model that provides both early detection and precise biological intervention, helping farmers achieve long-term disease control without relying on chemical pesticides.

2.1 What Is Our Product

We have designed an integrated detection–intervention program for bacterial wilt caused by Ralstonia solanacearum, which consists of two major parts:

Indigo Test Strain (E. coli BL21 / pPA1897-TnaA-FMO):

Used to rapidly determine disease risk in the field.

Laboratory Salicylic Acid Intervention Preparation:

Produced through fermentation using an engineered intervention strain (E. coli BL21 / pPA1897-ICS-IPL) and purified for application to infected crops in the field.

Both components rely on the same QscR–AHL quorum sensing mechanism.

The detection strain first recognizes the early quorum signal of R. solanacearum, and based on the detection results, the corresponding salicylic acid preparation is synthesized in the laboratory.

This forms a closed-loop system of “field early warning – laboratory preparation – field application.”

2.2 Function

Incubation-Period Field Warning:

The soil extract reacts with the test strain, and the presence of bacterial wilt in the incubation period can be determined by a blue color change visible to the naked eye.

Detection requires no laboratory equipment and does not damage crops.

Precise Intervention and Control:

If a blue change is observed during testing, an appropriate amount of salicylic acid preparation is produced in the laboratory.

Root irrigation of the preparation can induce the crop’s Systemic Acquired Resistance (SAR) and effectively block disease development.

2.3 Benefits

• Fast — Rapid detection results within a short time, much more efficient than traditional methods.
• Simple — Field testing requires only visual observation; the lab then prepares the salicylic acid preparation, with no complex operation needed by farmers.
• Green — No chemical additives are introduced into the soil. Salicylic acid is biosynthesized by engineered bacteria and applied after purification.
• Low Cost — Testing costs are far lower than traditional molecular detection, and large-scale salicylic acid production further reduces total control costs compared with “chemical pesticides + post-damage remediation.”

2.4 Improvements Compared with Existing Market Products

2.5 About Ethics

Because our salicylic acid preparation is biosynthesized and purified in the laboratory rather than directly produced or released into the soil, its negative environmental impact is minimal.

Therefore, our project fully complies with ethical and biosafety management standards.

2.6 Conclusion

Our method follows the cycle of “field detection – laboratory preparation – field treatment.”

This approach enables rapid disease detection, standardized salicylic acid production, and early, eco-friendly intervention, transforming bacterial wilt control from “passive response” to “active prevention.”

3. About Cost

Tool Usage Classification and Maintenance Cost Description

Long-term Use Tools

Tool Name: Ruler, Temperature-controlled Fermentation Box, 3D Printing Shaker, Continuous Injector, Water Sampling Device

Maintenance Cost: Maintenance cost exists

Short-term Use Tools

Tool Name: Blood Collection Needle

Maintenance Cost: No maintenance cost required

Note Release Area

• The notations such as "10×3" in the maintenance cost column indicate: single-year cost × 3-year usage cycle
• There are two independent cost calculation models for blood collection needles
• All currency units: Renminbi (RMB)

4.1 Market Demand

Because bacterial wilt occurs frequently in southeastern China and the disease is difficult to detect at an early stage, it is often discovered only after plant wilting.

Early detection methods are usually expensive and require laboratory equipment.

To address this issue, our team has developed a low-cost detection and treatment system that allows farmers to identify and prevent bacterial wilt early with minimal expense.

4.2 Target Market

Our target customers are primarily farmers and agricultural cooperatives in regions that are severely affected by bacterial wilt.

Considering their economic capacity, we plan to reduce production and sales costs to make our product affordable and accessible, ensuring successful market entry and adoption.

4.3 Competitive Advantages

Compared with other products on the market, our system offers clear advantages:

• Lower cost – Simple operation greatly reduces testing expenses.
• Easier to use – No laboratory or specialized equipment is required.
• More environmentally friendly – Causes minimal negative impact on soil and the surrounding ecosystem during treatment.

5.1 Product Promotion

We plan to visit farms and demonstrate our product’s performance in the field.

In addition, we will collaborate with agricultural cooperatives to promote the product jointly.

We will also utilize advertising campaigns and social media platforms to reach a broader customer base.

5.2 Annual Plan

5.2.1 First Year

• Study laws and regulations related to product safety.
• Demonstrate, through experiments, that the application of salicylic acid has no negative environmental impact.
• Apply for a pesticide registration certificate from the Guangzhou Agricultural Department.
• Discuss with the Ecological Environment Bureau and other agencies to assess environmental impact.
• Submit the product for quality inspection by the Market Supervision Administration of Guangzhou.
• Conduct market demand surveys and determine pricing according to supply–demand dynamics.

5.2.2 Second Year

• Complete safety testing and obtain certificates such as pesticide registration and product safety certification.
• Begin small-scale production and trial sales in local farmland.
• Cooperate with agricultural cooperatives for promotion and outreach, and develop a marketing plan.
• Seek potential investors or bank loans to support product expansion.
• Host educational seminars in rural areas to raise awareness of bacterial wilt and our solution.

5.2.3 Third Year

• Summarize the revenue and feedback from previous sales, and adjust pricing according to market demand.
• Optimize product design to make the system more user-friendly (e.g., potential seed-based prevention).
• Expand the market beyond Guangzhou to other provinces and international markets.

5.3 Long-Term Vision

Continuously improve technology and product performance to reduce potential user errors and enhance system stability and reliability.

6.1 Funding Risks

If costs and pricing are not properly controlled, we may face cash flow shortages or financial instability.To mitigate this, we will implement comprehensive cost control and financial management strategies.

6.2 Technology Risks

Failure to maintain technological advancement may cause us to fall behind market demand.We will continue to upgrade our technology and strengthen intellectual property protection to prevent imitation by competitors.

6.3 Policy and Legal Risks

We will closely monitor relevant government regulations and policies to ensure that our product remains compliant, legal, and safe in all markets.

Through market research, we have identified that the frequent outbreaks of bacterial wilt in southeastern China have seriously reduced crop yields.

Because of its long incubation period, farmers often notice symptoms only after the plants have died, and existing early detection methods are too costly.

Our low-cost, field-based detection and intervention system enables early observation and timely treatment, helping reduce disease incidence, improve yields, and promote sustainable agricultural development.