Countermeasures for Tea Gardens Affected by High Temperature and Heat Stress
During the height of summer, tea plants are susceptible to extreme weather conditions such as high temperatures and droughts, which can severely impact their normal growth, yield, and quality. Therefore, implementing measures to prevent and respond to droughts and heat stress in tea gardens is crucial to minimize economic losses. After tea plants suffer from drought, garden management should focus on the following:
1
Differentiate Levels of Drought Damage Caused by High Temperatures
After a tea garden experiences high temperature and drought damage, it can generally be categorized into four levels:
Light – some leaves gradually turn yellowish-green, develop brown spots, and slightly curl or deform;
Moderate – most tender leaves (1-4 leaves) turn reddish-brown, curl, wilt, become scorched, and fall off, but the top buds (1 bud with 2 leaves) are not completely dead;
Severe – old and young leaves scorch and fall off, resulting in bare branches, and many branches die, although the main trunk is not completely dead;
Extreme – the root system dies, all leaves fall off, and the ground-level branches and main trunk wither, leading to the death of the entire plant.
2
Preventative Measures for Managing High Temperatures and Droughts in Tea Gardens
(a) Improve Water Management Facilities and Monitor Drought Conditions
In hillside and mountainous areas, use favorable terrain to construct water ditches, channels, reservoirs, and ponds to increase water storage capacity. In regions prone to drought, closely monitor drought conditions and implement preventative measures in advance.
(b) Timely Irrigation and Scientific Shading
During the dry seasons of summer and autumn, when the relative soil moisture content in the cultivated layer drops to around 70%, or when the daily average temperature reaches above 28°C without rainfall for 7-10 days, schedule water supply and apply irrigation using sprinklers or furrow irrigation methods to replenish water. Sprinkler irrigation should be carried out during the early morning or evening; where possible, spray twice a day, avoiding irrigation between 10 am and 5 pm. For gardens with good terrain, set up shade nets at a height of 1.8-2.0 meters above the ground to prevent direct sunlight, effectively reducing light intensity and alleviating drought conditions.
(c) Light Cultivation, Weeding, and Mulching with Straw
Before the onset of the dry season, cultivate the tea garden lightly and remove weeds to reduce surface evaporation. Where feasible, cover the garden with straw to lower temperatures and retain soil moisture. Suitable materials include wild grasses, crop stalks, sugar cane residue, wood chips, etc. Use approximately one ton of dry straw per acre, laid to a thickness of 5-10 centimeters.
3
Recovery Measures for Tea Gardens After Drought Relief
(a) Appropriate Pruning at the Right Time
After the drought eases, pruning should be performed promptly based on the severity of branch and leaf Drying. Light pruning, deep pruning, or even stump cutting may be necessary to remove dead branches and regrow a healthy canopy. For gardens with mild drought damage, only showing a few burnt spots on mature leaves, pruning should be light, typically 1-2 cm below the damaged area. However, for gardens with severe damage from high temperatures and drought, where numerous dead branches appear on the canopy, pruning should be conducted 2-3 cm below the dead parts immediately after the drought eases. Regardless of whether pruning is done, affected tea plants should be left to recover and strengthen their canopies.
(b) Timely and Scientific Fertilization
For severely affected gardens, when the high temperature and drought have subsided and the soil is moist after rain, fertilization should be applied scientifically. It is recommended to start applying the base fertilizer for autumn and winter earlier, using about 150-250 kg of rape Seed Cake or 300-500 kg of commercial organic fertilizer per acre, along with 30-40 kg of compound fertilizer. Apply these fertilizers deeply in trenches 20 cm deep between the rows, covering them with soil afterward to promote deeper root growth. In early spring of the following year, apply quick-release fertilizers, such as 8-10 kg of urea per acre in trenches, or foliar sprays of nutritional foliar fertilizers, which will significantly aid the recovery of the tea plants and ensure the yield and quality of the spring tea.
(c) Retain Autumn Tea Leaves for Regeneration
For gardens that need to harvest autumn tea, after high temperature and drought disasters, more leaves should be retained and less harvested, and the garden should be closed early to allow the tea plants to recover and reduce the impact on the yield of the next spring tea.
(d) Promptly Replant Dead Seedlings
Especially for young tea gardens, if seedlings die, they should be replanted in the autumn or winter of the same year. For gardens where severe high temperatures and droughts lead to the death of many seedlings, the soil should be deeply plowed, enriched with additional soil, and any obstacles in the garden soil removed before replanting new seedlings. For areas unsuitable for growing tea, consider alternative uses.
(e) Implement Disease and Pest Control to Prevent Overlapping Disasters
Young tea seedlings, due to their tender and lush foliage, are vulnerable to pests like the Green Tea leafhopper and the gray tea geometrid moth. Pesticides such as Bacillus brevis and flonicamid can be used to control these pests, ensuring the healthy growth of the seedlings and enhancing their drought resistance.