During the winter season, cold air often occurs. Before the arrival of cold air, frost protection work should be done for citrus production, especially in orchards where branches and leaves are tender or tree growth is weak. It is essential to ensure appropriate field moisture in the orchard. Let's talk about the main measures for frost protection in citrus fruit trees.
Main Measures for Frost Protection in Citrus Fruit Trees
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Site Selection: When planting citrus on hilly slopes, choose sunny slopes sheltered from the wind. For flatland orchards, windbreak belts should be established on the east, north, and west sides of the orchard. Windbreaks can be made of evergreen trees like camphor and privet.
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Use Cold-resistant Citrus Varieties: Citrus belongs to the Rutaceae family – Citrus subfamily, evergreen fruit trees with a wide range of varieties and differences in cold resistance. Among the citrus varieties currently planted, their cold resistance varies from strong to weak, namely: Wenzhou Honey Pomelo, Nanfeng Honey Orange, Ponkan, Navel Orange, Tangerine (hybrid of orange and tangerine), and Grapefruit. When selecting varieties, choose those suitable for the local climate.
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Timely Application of Base Fertilizer: The time for applying base fertilizer for citrus should be completed locally between late October and mid-November. Applying fertilizer too early may promote slight budding in late autumn, which consumes nutrients and reduces cold resistance, while applying it too late is not conducive to the healing of root wounds due to low soil temperature.
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Watering in the Orchard: Starting from the middle to late November, watering should begin in the orchard. In the absence of rain during winter, the soil in the orchard should be kept moist. According to the weather forecast, water should be replenished 3-5 days before the arrival of cold waves.
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Whitewashing the Main Stem and Mounding Soil: Use 30-40% lime solution to whitewash the main stem and mound soil around the grafting interface between ground plants and rootstocks, with the soil mound reaching a height of over 30 centimeters. Whitewashing and mounding soil can reduce the damage caused by snow melting and prevent bark cracking after freezing.
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Spraying Anti-transpiration and Insulation Agents: 5-7 days before the arrival of cold air, spray the entire canopy with a 200-fold diluted anti-transpiration and insulation agent. Immediately after the cold wave, repeat the spraying.
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Covering the Canopy: When the minimum temperature drops below zero degrees Celsius, cover the canopy with non-woven fabric or plastic film. After the cold wave passes and it turns sunny, uncover the canopy during the day when the temperature is above 5 degrees Celsius, and cover it again at night to prevent frost. If conditions permit, simple plastic greenhouses can be built for insulation before late November.
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Removing Snow from the Canopy: When encountering heavy snowfall, shake the canopy branches timely to dislodge the snow and prevent branches from breaking under the weight of snow.
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Ground Application of Quicklime: On clear nights after snowfall, spread 50-100 kilograms of granular quicklime per mu in the orchard. Quicklime releases gas through decomposition, which can raise the temperature in the orchard and reduce the harm caused by radiation cooling.
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Foliar Fertilization: After the cold wave, on sunny days around noon (between 10 am and 3 pm), spray water every 1-2 days continuously for 5-6 times. Around every 7 days, spray a solution of 0.3% urea and 0.2% potassium dihydrogen phosphate once for 3-4 consecutive times. This helps reduce dehydration and leaf drop due to freezing and restores tree vigor.
Above are the main measures for frost protection in citrus fruit trees. With low winter temperatures, citrus fruit trees may suffer from varying degrees of cold damage, which requires attention and adequate preparation to minimize losses.
