What to Do When Grapes Suffer Frost Damage? The Latest Prevention and Remedial Methods

Every winter, especially in northern regions, as temperatures drop sharply, frost damage is an important cause of low grape yields, and almost every year some regions see reduced yields due to the impact of frost damage. In unusual years, such as when low temperatures arrive early in winter, extreme temperatures are too low, low temperatures last a long time, or late frost occurs, grapes are affected by frost damage particularly severely, with huge losses. Below is an introduction to the two classifications of grape frost damage and some methods for addressing the threat of frost damage.

I. Classification of Frost Damage

Grape frost damage is mainly divided into two types: dormant-period frost damage and growing-period frost damage.

Dormant-period frost damage in grapes mainly occurs at the roots and the trunk near the ground. Its obvious symptoms are that the grape vines bud late or do not bud; sometimes they bud late or do not bud, and sometimes after new shoots grow they gradually die back shortly afterward, while some new shoots appear as yellow leaves; in some cases the upper branches die back, while many new branches sprout from the part near the ground. When the trunk near the ground is cut open, the phloem turns brown to dark brown, and the cambium is damaged or necrotic.

Growing-period frost damage in grapes mainly occurs during the tender shoot growth period. If strong low temperatures occur after budding, the tender shoots turn dark brown and die.

Late burial in soil after the vines are taken down from the trellis, or too thin a covering layer of soil, is the main cause of dormant-period frost damage in grapes. Excessive fruiting, early defoliation, and low nutrient accumulation in the tree can aggravate the degree of dormant-period frost damage in grapes. For young grape vines, excessive fertilizer and water, overly vigorous branch growth, and insufficient lignification make them prone to grape frost damage.

II. Solutions

1. During the growing period, adopt a technique of promoting early and controlling later to promote vine maturity. The main method is to supply nitrogen fertilizer and water before mid-July to promote more grape branches and leaves, and after mid-July apply more phosphorus and potassium fertilizer, control water, and pinch early to promote branch maturity.

2. Increase the nutrients stored in the tree. Methods that can be used include appropriately controlling the grape fruit load; harvesting at the right time to reduce nutrient consumption; strengthening fertilizer and water management after picking, promptly controlling pests and diseases, extending the functional period of leaf photosynthesis, and increasing nutrient accumulation.

3. Strengthen measures against low-temperature chilling injury. Before a cold wave arrives, you can increase humidity and protect against cold by irrigating the grapes and spraying water on the leaves, thereby reducing chilling injury; when the cold wave arrives, you can heat the grapes to increase temperature and humidity; after the grapes are fully harvested and taken down from the trellis, bury them in soil promptly to protect against cold, and appropriately increase the thickness and width of the soil covering to improve the cold-protection effect.

The above content is three suggestions put forward regarding the frost damage problems grapes may face during overwintering, hoping to provide some useful advice for everyone in the process of cold protection.