Parts of Fruit Trees Prone to Freeze Damage in Winter and How to Prevent It

For fruit trees, it is very easy to suffer freeze damage in relatively cold winters. Without targeted preventive measures in place, it is undoubtedly a considerable blow for fruit growers. So which parts of fruit trees are prone to freeze damage in winter? How to prevent it?

1. Which parts of fruit trees are prone to freeze damage in winter?

1. Root freeze damage

Because fruit tree roots have no natural dormancy, roots at the soil surface are prone to freeze damage. When roots are frozen in winter, it is often not easy to detect. The following spring, after the branches sprout, if the shoots and buds suddenly wilt after some time, it is mostly caused by frozen roots. Preventive measures: prevent early defoliation, control growth and promote vigor in autumn, promote nutrient accumulation, and water thoroughly with frozen-water irrigation.

2. Root crown freeze damage

Because the root crown stops growing the latest and starts activity earlier, its cold resistance is poor, and at the same time it is close to the soil surface where temperature changes greatly, so the root crown is susceptible to damage from low temperatures and large temperature fluctuations, causing the cortex to freeze, turn brown in a ring shape, and then dry up or rot. Preventive measure: mound soil around the root crown.

3. Trunk freeze damage

First, sunscald on the sunny side of the trunk: because the temperature difference between day and night is large in early winter and early spring, the bark tissues become active as the temperature rises with sun exposure, and then freeze when the nighttime temperature drops sharply. Second, vertical cracking of the trunk: because the temperature drops sharply in early winter, the cortical tissues rapidly contract with cold, and the xylem generates stress that splits the bark open; ice forming in intercellular spaces can also cause cracks. Preventive measures: whitewash the trunk, wrap the trunk with straw.

4. Branch fork freeze damage

It mainly occurs on the inward-facing side of the fork. Symptoms are discoloration of the cortex, necrotic depressions, or vertical splitting downward on the trunk. Because the fork has narrow annual rings, underdeveloped vessels, poor nutrient supply, little stored nutrition, and poor cold resistance, the vessels rupture, causing gumming at the branch fork the following spring. At the same time, because snow easily accumulates at the fork, after the snow melts it soaks the bark and makes the tissues soft, so a sudden drop in temperature will cause damage. Methods such as wrapping the trunk with straw and hanging straw on branch forks can be used for cold protection.

2. How to prevent freeze damage to fruit trees in winter?

1. Strengthen fertilizer and water management

Strengthening fertilizer and water management helps store nutrients in the tree body. Strengthening fertilizer and water in spring can also promote new shoot growth and leaf enlargement, improve photosynthetic efficiency, and ensure the tree remains vigorous. In autumn, controlling irrigation, draining waterlogged areas in time, applying an appropriate amount of phosphorus and potassium fertilizer, and weeding and deep plowing can promote the timely cessation of branch growth, help tissues become compact, and extend the accumulation of nutrients.

2. Winter irrigation at the right time, irrigate with frozen water

Reasonable winter irrigation can both ensure that the aboveground parts of the plant absorb sufficient water and protect the underground root system against the dry and windy winter, extending the flowering period of flowering plants the following year. Generally, when the ground temperature is above 5°C, plant roots absorb water; below 5°C, plant roots cannot absorb water. Therefore, water thoroughly once before the ground temperature drops below 5°C. When the ground temperature is below 0°C, the soil will freeze because of its water content; at this time also water once to keep the root system from being dried out by the wind. When the temperature is even lower, the frozen water at the roots can release latent heat and raise the temperature. Therefore, winter irrigation should be carried out 2 times, in late October and early November.

3. Strengthen freeze-proofing and heat-preservation measures:

1) Mound soil at the root crown

After winter watering is completed, in combination with sealing the basin, mound soil at the root crown of the tree to form a mound 50-80 cm in diameter and 30-50 cm high. This can prevent low temperatures from freezing and injuring the root crown and tree roots, and can also reduce soil moisture evaporation.

2) Cover with soil

In early spring, when the soil has not yet thawed, tree roots find it difficult to absorb water. At this time the air is dry, the temperature rises quickly, and evaporation is high, which can easily cause physiological drought in plants and dead shoot tips. In response to this phenomenon, around the Start of Winter the seedlings can be buried in soil for the entire winter, keeping the seedlings and seedbed soil at a certain temperature and free from sharp temperature changes and other adverse external factors. At the same time, it can also reduce the transpiration of seedlings and the evaporation of soil moisture, maintain a certain amount of soil moisture, help maintain the water balance in the seedlings, and effectively prevent death caused by freeze damage and physiological drought of the seedlings.

3) Set up wind barriers

To reduce the damage from freezing drought caused by cold, dry strong winds blowing on trees, wind barriers can be set up on the windward side of the trees.

4) Bind the trunk

This means using rice straw, stalks, dry grass, and so on to bind the trunks of fruit trees, achieving a cold-protection effect by increasing the thickness of the trunk, just like adding clothes when it is cold.

4. Use fruit tree whitewash

Trunk whitewash is a product used for pest prevention and thermal protection for various trees such as landscape trees, ecological forest trees, street trees, and fruit trees. It effectively blocks ultraviolet rays, protects the trunk cortex, reduces damage caused by sunscald, and has the characteristics of cold protection, pest prevention, disease prevention, killing insect eggs, and preventing damage from rodents and rabbits. The coating can both prevent tree aging and serve as thermal insulation for trees, enabling them to grow better; special material treatment gives it long-term adhesion and prevents rain from washing it off. For a whitewash product, Wulingdun whitewash can be selected.