Research progress of orchard plant protection mechanization technology and equipment in China

Abstract: Orchard spray is a key link to orchard production, due to it occupied nearly 25% of the total workload of orchard management. Moreover, the degree of plant protection mechanization directly affects the economic benefits of fruits. In this review, the orchard characteristic, the general situation of plant protection mechanization and the reasons restricting its development were introduced briefly, in order to clarify the future progress of mechanization technology and equipment for the orchard plant protection in China. The main reason impeding the development of plant protection mechanization can be a large proportion of hilly orchards, including gradient, slope and flat orchard, together with a very complex planting environment. Since the standardized modern orchards are being promoted, the scale is still small, due partly to the extensive management in traditional orchards the high price. Currently, the plant protection mechanization level of flat orchard was 15%, whereas, the hilly orchard was only 7.5%. Therefore, the progress of key plant protection mechanization technologies and equipment was presented in detail, further to improve the mechanization level of plant protection. For example, the pipeline spraying technology and equipment brought good benefits and spraying effects to the hilly orchard, while, the application of air-assisted spraying technology and equipment improved the mechanized operation level of the flat orchard. Electrostatic spraying technology and equipment were especially used to enhance the droplet coverage rate on the back of leaves. While the tunnel spraying technology and equipment increased the droplet density on the canopies, to recovery the droplet that left the target, indicating that it can effectively improve the pesticide utilization. Variable rate spraying technology and equipment were becoming a hot research topic, particularly on the precise control of spray on demand. The core technology of variable rate spraying was target detection, such as ultrasonic detection, laser detection, infrared detection, machine vision methods. The ultrasonic and laser detection methods have achieved the best application. Since 2010, the great development and application of aerial spraying technology and equipment have been widely recognized. Especially, the unmanned aerial vehicle (UAV) of rotor plant protection has become one of the most popular machines with small size, fast flight speed and strong terrain adaptability among the agricultural aerial equipment. In this review, the research state of rotor plant protection UAV in orchard was introduced from three aspects: operation model, downwash flow field, and working parameters. Plant protection equipment can offer some suggestions for the development of plant protection mechanization from these aspects: promoting standardized models of orchard plant, developing stereo spraying technology, promoting specialized and mechanical service model of plant protection, thereby for the intelligent robots of plant protection.