How to reduce the application of chemical pesticides in Tea gardens and avoid or minimize the damage caused by diseases and pests to tea yield and quality is the primary task for tea plant protection workers. To accomplish this task, it is not only necessary to innovate and develop alternative technologies to chemical pesticides but also equally important to scientifically and reasonably integrate these technologies for their combined application.
I. Basic Principles of Integrated Green Control Techniques
1. Adherence to the Basic Principles of Integrated Pest Management (IPM)
The integrated application of green control techniques places more emphasis on enhancing field biodiversity and protecting natural enemies, by assembling and using a variety of different natural-enemy-friendly control techniques to minimize the use of chemical pesticides. Based on crop healthy cultivation, good agricultural practices are assembled and used. The scientific use of pesticides should be initiated to eliminate highly toxic, persistent, and polluting pesticides.
2. Simplicity and Convenience
The purpose of integrating green control techniques is to promote their application and use. Through further technical development, assembly, and standardization, complex techniques can be simplified, thus increasing the adoption rate of new green control technologies and addressing the issues of high costs and labor input.
3. Standardization and Normalization
The basic process of integrating green control techniques consists of four repeating cycles: technique selection, applied technique research, technique assembly and matching, and technique standardization. In this process, the selection and assembly of green control techniques should start from the overall perspective of the farmland ecosystem, aiming for sustainable and efficient management of diseases and pests, improvement of ecological benefits generated by ecosystem services, and enhancement of social benefits produced by improved quality of agricultural products, rather than solely focusing on short-term effects and simple pursuit of economic benefits. Applied technique research and technique standardization should consider the simplification and standardization of techniques.
II. Selection of Green Precision Control Techniques
1. Precise Physical Trapping Techniques
Precise physical trapping techniques mainly include narrow-band LED insect traps and yellow-red double-color sticky boards. Insect traps are an essential tool for physical trapping of pests in tea gardens and serve as the first line of defense. Based on the differences in phototaxis spectra between major tea garden pests and dominant natural enemies, a precise LED light source for trapping tea garden pests was determined, and a narrow-band LED insect trap with a wind suction negative pressure device was developed. Sticky boards are the main technique for controlling tea green leafhoppers, thrips, and black scale insects. Using yellow-red double-color natural-enemy-friendly sticky boards after Spring Tea pruning can reduce the peak population of tea green leafhoppers by at least 30%.
2. Sex Pheromone Trapping Technique
Sex pheromones are information substances released by female Lepidoptera pests during mating that male pests use to locate females. The sex pheromone trapping technique utilizes artificial sex pheromones, known as sex attractants, to lure male pests for mating, reducing the probability of mating in the field and subsequently decreasing the number of the next generation of pests. Sex attractants have the advantages of being highly effective, specific, requiring low dosage, not harming natural enemies, and not polluting the environment. Highly effective sex attractants have been proposed for eight major tea garden pests, including the gray tea geometrid moth, tea geometrid moth, tea tussock moth, tea silkworm, tea black geometrid moth, Hunan yellow leafroller, tea leafroller, and tea gelechiid moth. For example, the highly effective sex attractant for the gray tea geometrid moth can achieve a 50% control effect on male moths of the first generation; continuous trapping for two generations can reach a 67% control effect.
3. Biological Control Techniques
Biological control includes biological pesticides and release of natural enemies. Currently, for Lepidoptera pests in tea gardens, there are virus preparations, Paenibacillus lentimorbus, Bacillus thuringiensis, and other highly effective biological pesticides. Among them, virus preparations have strong specificity and long-lasting effects, while Paenibacillus lentimorbus has a certain broad-spectrum and rapid action. For small sucking pests like tea green leafhoppers and tea thrips, there are pyrethrum, azadirachtin, tea saponins, and other botanical pesticides. However, the control effects of these biological pesticides are not ideal, which can be improved through mixed use and increased application frequency. Regarding the release of natural enemies, the most commonly used method in production is releasing predatory mites to control tea plant pests. When the number of pest mites such as Eriophyidae and tea red spider mites is rising, releasing 1.02 million Amblyseius cucumeris per hectare at the initial stage can achieve an 80% control effect.
Application Technology Model of Tea Nucleopolyhedrovirus-Bacillus thuringiensis Suspension Agent (10,000 PIB/μL of Tea Geometrid Moth Nuclear Polyhedrosis Virus + 2,000 IU/μL of Bacillus thuringiensis) in Southern China's Tea Region
4. Good Agronomic Practices
Good agronomic practices include sealing the garden with lime sulfur in autumn and winter, deep plowing and fertilizing in winter, proper pruning, and frequent harvesting. Sealing the garden with lime sulfur in autumn and winter has a good preventive effect on reducing mite and leaf disease incidence in the early part of the following year. Winter deep plowing can destroy the overwintering habitats of pests like geometrid moths and weevils, reducing pest numbers the following year. Since tea aphids, tea green leafhoppers, tea red spider mites, and tea eriophyid mites primarily occur on young shoots, proper pruning and frequent harvesting can remove a large number of pests and worsen the conditions for these pests to thrive.
5. Chemical Control
Chemical pesticide control is also an indispensable technique in the green precision control of tea garden pests. The use of chemical pesticides largely ensures tea yield and quality, especially during outbreaks of pests when they provide immediate results. For some time to come, chemical pesticides will continue to play an important role. To ensure the safety of tea drinkers to the greatest extent, pesticides with low water solubility and low environmental risks should be selected, and their use should be standardized.
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