What to do about frost damage in grapes? Getting these few points right is enough

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 because of frost damage. In unusual years, such as when low temperatures arrive early in winter, when extreme temperatures drop too low, when low temperatures last a long time, or when late frost occurs, grapes are affected by frost damage especially severely, with huge losses. Below is an introduction to the two classifications of grape frost damage and some ways to deal with the threat of frost damage.

I. Classification of frost damage

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

Frost damage to grapes during the dormant period mainly occurs at the roots and the trunk near the ground. Its obvious symptoms are that the grape vines sprout late or do not sprout; sometimes they sprout late or do not sprout, and sometimes shortly after new shoots grow they gradually die back; some new shoots appear yellow-leaved; some show dead upper branches 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.

Frost damage to grapes during the growing period mainly occurs during the young shoot growth stage. If strong low temperatures occur after sprouting, the young shoots turn dark brown and die.

Late hilling or a relatively thin soil cover after the grapes are taken down from the trellis is the main cause of dormant-period frost damage in grapes. Excessive fruiting, early defoliation, and low nutrient accumulation in the tree body can worsen the degree of dormant-period frost damage in grapes. For young grape vines, excessive fertilizer and water, overly vigorous shoot growth, and insufficient lignification make them especially susceptible to grape frost damage.

II. Solutions

1. During the growing period, use the technique of promoting early and controlling late 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 early to promote shoot maturity.

2. Increase the nutrients stored in the tree body. Methods that can be used include appropriately controlling the grape fruit load; harvesting at the right time to reduce nutrient consumption; and after picking, strengthening fertilizer and water management, timely 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 and increase humidity for the grapes; after the grapes are fully harvested and taken down from the trellis, cover them with soil in time to protect against cold, and appropriately increase the thickness and width of the soil cover to improve the cold-protection effect.

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