What about the freeze injury of grapes?

In winter every year, especially in the northern region, with the sharp drop of air temperature, freezing injury is an important reason for the low grape yield. In special years, such as early arrival of low temperature in winter, too low temperature, long duration of low temperature or late frost, grapes are particularly affected by frost injury, resulting in huge losses. Here are two categories of grape freezing injury and some ways to solve the threat of grape freezing injury.

I. classification of frost damage

The freezing injury of grape can be divided into two types: dormant period and growing period.

During the dormant period, the freezing injury of grape mainly occurred in the root and the trunk near the ground, and its obvious symptoms were that the grape branches germinated late or not, sometimes they germinated late or did not germinate, and sometimes the new shoots gradually withered and died soon after sprouting and growing new shoots, while others showed that the upper branches withered and many new branches sprouted near the ground. Cut open the tree trunk near the ground, the phloem turns brown to dark brown, and the cambium is damaged or necrotic.

During the growing period, the freezing injury of grape mainly occurred in the growing period of tender shoots, and if a strong low temperature occurred after germination, the tender shoots became dark brown and withered.

The late buried soil or thin buried soil layer after grape off the shelf is the main reason to induce the freezing injury of grape during dormancy period. Too much grape fruit, early defoliation and less nutrient accumulation can aggravate the occurrence of frost injury in dormant period. For young grape trees, too much fertilizer and water, overgrowth of branches and insufficient degree of aging are easy to suffer from grape freezing injury.

II. Solutions

1. During the planting period, the pre-promotion and post-control technology was adopted to promote the maturity of the branches. The main method is to supply nitrogen fertilizer and water before the middle of July to promote the growth of grape branches and leaves, and to apply more phosphorus and potassium fertilizer after the middle of July to control moisture, pick the heart as early as possible and promote the branch ripening.

two。 Increase the nutrients stored in the tree. The methods that can be adopted are to properly control the fruit amount of grapes, timely harvest to reduce nutrition consumption, strengthen fertilizer and water management after picking, control diseases and insect pests in time, prolong the functional period of leaf photosynthesis and increase nutrient accumulation.

3. Strengthen measures to resist low temperature and cold damage. Before the arrival of the cold current, the grapes can be moistened and protected against cold by irrigation and foliar spraying, and the cold injury can be reduced by heating and humidifying the grapes. After the grapes are picked and removed from the shelves, they should be buried in time to prevent the cold, and appropriately increase the thickness and width of the buried soil to improve the cold-proof effect.

The above contents are three suggestions on the problem of freezing injury that grapes may face in the process of overwintering, hoping to provide some useful suggestions for everyone in the process of cold prevention.