What to Do About Grape Frost Damage? A Detailed Guide to Practical Remedies

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 areas see reduced yields due to the effects of frost damage. In unusual years, such as when low temperatures arrive early in winter, when extreme temperatures are too low, when low temperatures last a long time, or when late frosts occur, 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 dealing with 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.

Grape dormant-period frost damage 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 shortly after budding and producing new shoots, the new shoots gradually die; some new shoots appear as yellow leaves; in some cases the upper branches die 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.

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

Late earthing up after the grapes are taken down from the trellis, or too thin a layer of soil, is the main cause of dormant-period frost damage in grapes. An excessively large grape fruit load, early defoliation, and relatively low nutrient accumulation in the tree can worsen the degree of dormant-period frost damage in grapes. For young grape trees, 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 the 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 to apply more phosphorus and potassium fertilizer, control water, and pinch the tips early to promote branch maturity.

2. Increase the nutrients stored in the tree. The 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 preventing and controlling pests and diseases, extending the period of leaf photosynthesis, and increasing nutrient accumulation.

3. Strengthen measures against low-temperature cold damage. 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 cold damage; when the cold wave arrives, you can heat the grapes to increase humidity; after the grapes are fully harvested and taken down from the trellis, earth them up promptly to protect against cold, and appropriately increase the thickness and width of the soil to improve the cold-protection effect.

The above content is three suggestions for the frost damage problems that grapes may face during overwintering, and I hope they can provide some useful advice for everyone in the process of cold protection.