Objective  An expert system for diagnosing citrus diseases and pests based on fault tree analysis was developed to solve the problems of insufficient popularization of professional plant protection knowledge and lack of efficient diagnosis methods in the prevention and control of citrus diseases and pests.

Method  First, fault tree analysis method was used to calculate the occurrence probability of diseases and pests and establish a knowledge base of diseases and pests. Secondly, based on the knowledge base and forward reasoning strategy, the reasoning engine of the expert system was designed and implemented. Finally, Weixin DevTools were used to equip the calculation rules of fault tree analysis method and the inference engine of expert system in weixin mini program, and build the expert system based on fault tree analysis method.

Result  We established an expert system for diagnosing citrus diseases and pests with five functional modules: Pest knowledge module, latest information module, knowledge base query module, diseases and pest diagnosis module as well as user center module. After testing, the system could run smoothly in different types of mobile phones. The average size of memory occupied was 175 megabytes, the average time for system startup was 1.0984 s and the average time for page switching was 0.0495 s. After running the system continuously for 1 h, the connection between the mobile phone and the server was normal.

Conclusion  The system is stable and reliable, and the page style is displayed normally. Users can exploit the system to diagnose diseases and pests and obtain corresponding control methods. Meanwhile, users can also learn professional plant protection knowledge from the system.