Prevention and Control Methods for Bark Cracking and Trunk Dehydration in Young Jujube Trees

Yining County once developed jujube trees on a large scale. In years with heavy winter snowfall, when the snow melted in early spring, the trunk below the snow line (about 20 cm high) was soaked by melting snow water and exposed to wind, causing rot and bark splitting, which blocked the tree's vascular tissue and led to drying and death, resulting in heavy losses. Fruit growers wanted to develop the crop but worried about bark cracking and trunk dehydration. In recent years, when establishing new jujube orchards, we adopted the method of wrapping and protecting young trees with plastic film during the young stage, and the results were good.

I. Causes

1. Climate factors: Yining County has favorable climatic conditions, with an annual accumulated temperature of 3400°C at ≥10°C, 2800 hours of sunshine, annual rainfall not exceeding 600 mm, a frost-free period of 168 days, and a maximum snow depth in January of about 27 cm.

2. Variety factors: The main varieties cultivated in our county are Zanhuang jujube and pear jujube. Surveys of different varieties showed that the degree of damage to the two varieties was basically the same.

3. Topography and soil factors: According to surveys in many locations, it was found that in jujube orchards established on higher terrain with good ventilation and light penetration, the snow melted quickly and early in spring, no ice layer formed on the ground, and no trunk splitting occurred. However, in jujube orchards established in low-lying, humid, and wind-exposed areas, the bark cracked each year at about 20 cm below the snow line, causing the tree to dry and die because the vascular tissue was severed. Each spring, the trees were cut back to the ground and re-sprouted, flowered, and fruited. In some years the fruit could not mature, seriously affecting the economic income of fruit growers.

II. Measures

1. Strengthen field management of jujube orchards: Prune and train branches in a timely manner to cultivate robust trees. The key is to promptly spray insecticide on the ground and trunks in the orchard in autumn and apply whitewash. Prevent leafhoppers from laying eggs and damaging the trunks.

2. Adopt plastic film wrapping measures: Before snowfall in winter, wrap the trunk with plastic film (cut the film into strips 3 cm wide and 1 m long). From 25-30 cm above the ground, it must be wrapped tightly to prevent snow water from soaking the bark when it melts. In spring, after the snow has completely melted, remove the film promptly and spray fungicide. The effect is very good. This method should be used continuously for 2 years during the young tree stage. After the trees reach 3 years of age, the trunk bark thickens and ages, and once it has its own protective ability, bark splitting no longer occurs.

3. Summary: In the past, when developing jujube orchards, in order to explore ways to prevent trunk bark cracking, methods of wrapping with flax straw and waste cloth strips were adopted, but the results were poor. The method of burying soil easily caused broken branches and split trunks, resulting in missing rows and broken plants in jujube orchards. Since the promotion of plastic film wrapping protection technology in 2002, jujube orchards have developed rapidly.