The winter protection and management of Tea gardens is a key focus of tea garden management, critical for ensuring the yield, quality, and profitability of spring tea in the following year. To guide this year's winter protection and management of tea gardens, the Haiqing Town has developed technical guidance for winter protection and management of tea gardens in Qingdao Haiqing.
I. New (Renewed) Tea Gardens
(1) Select Cold-Resistant Varieties. Suitable cold-resistant varieties for planting in Haiqing Town include: Fuding Dabai, Huangshan Variety, Jiukeng Variety, Longjing Changye, Zhongcha 108, Longjing 43, Maolu, Jiukeng Early, Echa No.1, Bixiang Early, Yellow Rose, Jin Xuan, Pingyang Special Early, etc. When establishing a tea garden, try to use cold-resistant varieties as much as possible.
(2) Select Suitable Tea Garden Sites. Choose sites that are sheltered from wind and face the sun, with a thick layer of soil, acidic soil (pH value 4.5–6.5), and have irrigation facilities. The soil texture should be loam, sandy loam, or light clay loam.
(3) Create Windbreak Forests. Plant windbreak forests around the tea gardens, along roads, by ditches, on steep slopes, at the tops of hills, and in front of prevailing winds. Common tree species include: Chinese Arborvitae, Juniperus chinensis, White-barked Pine, Chinese Pine, Black Pine, Albizia julibrissin, Photinia, etc. Planting should be staggered, with a mix of tall and short trees, forming a triangular pattern. Shrubs should be planted on both sides.
II. Preparations Before Winter
(1) Soil Management
a. Adequate Deep Plowing. After the autumn tea harvest, plow the rows of tea plants deeply, to a depth of 15–20 cm. Clear dead branches, leaves, weeds, and insect-infested branches to reduce the incidence of diseases and pests in the following year.
b. Apply Adequate Base Fertilizer. Apply base fertilizer while deep plowing. Apply 1.5–2 tons per mu (approximately 0.067 hectares) of well-rotted organic manure, or 150–200 kg per mu of soybean cake, or 300–400 kg per mu of commercial organic fertilizer. For 1–2-year-old tea plants, open a fertilization trench about 15 cm wide and 15–20 cm deep parallel to the tea row, 10–15 cm away from the root neck. For 3–4-year-old tea plants, open a fertilization trench 20–25 cm deep, 35–40 cm away from the root neck. For mature tea gardens, open a trench deep under the outer edge of the canopy, 20–30 cm deep. For closed-row tea gardens, open a trench between two rows of tea plants, alternating sides every other year. (Note: Cover the soil after fertilizing, apply fertilizer early rather than late, and complete it by the end of October at the latest.)
c. Ensure Adequate Winter Water. Based on the soil moisture content, irrigate 1–3 times to ensure a moist soil layer thickness of more than 40 cm. This should be completed before the traditional Chinese calendar's “Major Snow” (Daxue). After watering, loosen the soil promptly to retain moisture. After “Major Snow,” if the soil is dry, replenish water before a significant drop in temperature.
(2) Moderate Pruning. Light pruning or topping can enhance the tea plant's ability to withstand winter. At the same time, prune drooping branches, branches near the ground, diseased and insect-infested branches, and weak branches. A single-sided pruning machine can be used, trimming diagonally towards the inside of the tea plant, improving ventilation and light transmission, reducing nutrient consumption, and reducing the number of overwintering pests.
(3) Winter Pest and Disease Control.
a. Comprehensive Control of Overwintering Pests. From mid-September to early October, it is the peak period for the migration of Green Stink Bugs into the tea garden and the emergence of adult insects within the tea garden (the specific time should be determined dynamically based on the number of insects attracted by pheromone traps in various areas). Ten days before and after the peak period, clear weeds inside and outside the tea garden and spray insecticides to reduce the number of overwintering eggs. Leafhoppers and black scale insects can also be controlled at the same time when treating Green Stink Bugs. At the same time, during pre-winter pruning, some eggs of Green Stink Bugs and leafhoppers, as well as nymphs and eggs of black scale insects, can be removed.
b. Control Diseases and Pests Using Stone Sulfur Solution. For tea gardens with severe pest and disease infestations, stone sulfur solution can be sprayed according to the situation. Generally, a diluted solution of 0.5 Be (Bé) (45% crystalline stone sulfur solution, mixed at a ratio of 500 grams of stone sulfur solution to 60–75 kilograms of water, stirring thoroughly) is used. The key areas to spray are the lower parts of the canopy where there are diseases and pests, as well as the undersides of leaves, branches, and dead branches and leaves where pests and diseases may hide, and the surface of the soil and corners with weeds. All these areas must be sprayed evenly and thoroughly. (Note: The water temperature for mixing the stone sulfur solution should be below 30°C; higher temperatures can affect the effectiveness of the pesticide. Avoid using too high concentrations to prevent leaf damage. Use the mixed pesticide immediately and finish it on the same day. The ideal temperature range for application is between 5–20°C; do not use the stone sulfur solution when the temperature is above 20°C or below 5°C. If it rains within 12 hours after spraying, consider re-spraying. For tea gardens that will be covered for winter, complete the treatment 30–40 days before covering to avoid leaf burn. Stone sulfur solution is a strong alkaline pesticide and cannot be mixed with Bordeaux mixture, copper-based pesticides, mineral oils, or pesticides that decompose easily in alkaline conditions. The stone sulfur solution can be corrosive to the skin and irritate the eyes and nose; wear gloves and a mask when using it. Maintain downwind application and take a shower and change clothes after work.)
III. Winter Protection Measures
(1) Soil Mulching for Winter Protection.
This method can be divided into full mulching and half mulching, suitable for 1–2-year-old tea gardens planted in sandy soil, loam, or sandy loam in the tea area.
a. Full Mulching. Done in two stages. The first stage is carried out around the traditional Chinese calendar's “Light Snow” (Xiaoxue), taking semi-dry and semi-moist soil from the large tea rows and mulching it up to half the height of the tea seedlings, being careful not to tilt or bend the tea plants. Do not take soil near the roots to avoid increasing frost damage due to root injury. Around “Heavy Snow” (Daxue), cover the entire plant, leaving only 1–2 leaves exposed.
b. Half Mulching. Before “Heavy Snow,” take semi-dry and semi-moist soil from the large tea rows and mulch the tea seedlings to about half their height. At the same time, set up windbreaks made of straw