Organic Tea Plantation Green Pest Management Measures (Part II)
III. Biological Control
Biological control methods achieve sustainable management of pests and diseases by utilizing natural enemy insects, releasing natural enemies, or applying biological agents.
An appropriate planting system can help regulate the ecological environment of tea plantations, improve soil fertility and physical properties, thereby facilitating crop growth and development as well as the proliferation of beneficial microorganisms, while also reducing the survival rate of pests. Tea plantations can benefit from the rational intercropping of shade-providing landscape trees such as black pine, white bark pine, sophora tree, ginkgo tree, and osmanthus tree. For instance, interplanting crops with repelling effects among tea trees can help deter pests and enhance the aesthetic appeal of the environment; for example, planting marigold or pyrethrum among tea trees can serve as a repellent against leafhopper pests. Planting lavender outside tea plantations allows its volatile compounds to attract small green leafhoppers and their natural predators—such as the Trichogramma wasp—while simultaneously releasing linalool, terpinen, and phellandrene, which exhibit repelling effects against the tea leaf roller moth.
In organic tea plantations, protecting natural enemy insects and creating suitable habitats for them is one of the key measures in biological control. Natural enemy insects—such as spiders, ladybugs, and parasitic wasps—can effectively prey upon pests like tea aphids and small green leafhoppers, thereby reducing their population density. Flowering plants grown in the fields—such as marigolds, pyrethrum, and lavender—can serve as nectar sources for these natural enemy insects. Maintaining weed cover between rows provides ideal sites for spiders to build their webs (a weed cover of 30%–50% is recommended).
The release of natural predators is also an important method of biological control; for example, releasing Trichogramma wasps can be used to control the tea leaf webworm. Apply 6,000 Trichogramma eggs per mu; upon hatching, these wasps locate the pest egg clusters and lay their own eggs on them. The parasitized eggs prevent the hatching of the larvae, thereby effectively controlling the pest population. To combat leafhoppers, release lacewings by applying 500–1,000 lacewing egg cards per mu. The release of predatory mites, such as Cuscuta aciculata, can be employed to control pest and mite infestations on tea plants; for instance, releasing 30,000 Cuscuta aciculata mites per mu can effectively reduce the population densities of pests and mites—including the tea orange gall mite, tea yellow mite, tea short-mite, and tea stem line mite.
When other green pest and disease control measures prove ineffective, the use of plant protection products that comply with organic farming standards may be permitted as an effective control measure. These products primarily include mineral-based, plant-derived, animal-derived, and microbial-based pesticides, as well as other substances approved for use by certified authorities. Mineral-based pesticides, such as copper hydroxide, can be used to control tea cake disease and tea webbing disease. Plant-derived pesticides, such as matrine and neem extract, possess strong insecticidal activity and can be applied to control pests including tea aphids and small green leafhoppers; however, the application concentration and frequency must be carefully managed to avoid causing phytotoxicity to tea plants. Sodium rosinate can be used to control angular wax aphids, red spider mites, and tea charcoal rot; amino-oligosaccharides can be employed to control tea anthracnose, tea cloud-pattern leaf blight, and tea red spot disease. Microbial-based pesticides, such as Metarhizium anisopliae CQMa421, can be used to control aphids and thrips; while the nuclear polyhedrosis virus of the tea leaf roller, Bacillus thuringiensis (Bt), the nuclear polyhedrosis virus of the tea leaf webworm, and Brevipilus teae can be used to control the tea leaf roller, tea caterpillar, and tea leaf rolling moth. The efficacy of these microbial control agents is significantly influenced by environmental conditions; therefore, the application timing should be carefully selected based on weather conditions. These biocontrol agents are characterized by high selectivity and safety toward non-target organisms, enabling effective pest and disease control without disrupting the ecological balance of tea plantations.
Furthermore, when applying plant protection products, it is essential to strictly adhere to relevant requirements to ensure that these products are traceable in origin, have clearly defined compositions, and do not pose any risk to the environment or human health. While plant protection products can help control pests and diseases to some extent, they should be combined with other eco-friendly pest management practices; this approach can significantly enhance the effectiveness of pest and disease control in tea plantations, while reducing reliance on chemical pesticides and supporting the sustainable development of organic tea farming.
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