How to Prune Grapevines for High Yield
Today, I will explain in detail how to prune grapevines for high yield and related topics about grapevine cultivation techniques during the winter, and the editor will introduce it next.
Grapes are a favorite fruit of people, and many farmers enjoy growing grapes. Among grape cultivation techniques, the pruning process is particularly important as it can adjust growth and fruiting, maintain strong tree vigor, manage rejuvenation, and achieve consecutive years of high yield. Today, I will talk about the methods of pruning grapevines in winter.
In areas where the vines are buried for winter protection, pruning is generally completed before taking them off the trellis (early November). In areas where the vines are not buried, pruning can be done throughout the dormant period, but pruning too early can reduce the cold resistance of the tree, and pruning too late may cause bleeding. It is generally recommended to finish pruning about one month before the start of bleeding in early spring.
1. Pruning Length
According to the retained length of the fruiting branches, they are divided into very long shoots (over 12 buds), long shoots (8-11 buds), medium shoots (4-7 buds), and short shoots (2-3 buds). Very short shoots (1-2 buds) are pruned. In production, a combination of long, medium, and short shoot pruning methods is often used; the traditional single trunk training method often uses short shoot pruning; while the regular fan shape should be a combination of long and short. In practical application, the retained length should be determined based on the vigor, position, function, and maturity of the branches. Generally, strong branches are retained longer, weak branches shorter; the ends are retained longer, and the bases shorter. Additionally, the tree shape and variety characteristics must also be considered. For some varieties with strong fruiting ability, such as玫瑰香 (Rose Honey), which have a high bud fertility rate at the base, medium to short shoot pruning can be used, while for varieties with vigorous growth and low fruiting ability, such as 龙眼 (Longan), medium to long shoot pruning should be used more often.
2. The Number of Fruit Bearing Branches to Retain
If too many branches are retained, the dense new shoots can affect the ventilation and light penetration of the trellis, leading to diseases and pests. Moreover, too much fruiting can weaken the tree and affect the quality and the next year's growth and development. Depending on the variety, methods such as slightly over-retaining branches during winter pruning and then determining the number of new shoots in the growing season or fixing the number of fruiting branches during winter pruning can be adopted, with the former being more secure. The number of fruiting branches can be calculated based on various factors such as the fruiting habits of the variety, target yield, and planting density. For example, with a row spacing of 3 meters by 2.0 meters and a planting density of 111 plants per 667 square meters, with a target yield of 1250-1500 kilograms, each plant should yield 12-14 kilograms. If the average weight of a single cluster is 300-400 grams, achieving the target yield per plant requires about 35 clusters. On average, one fruiting branch produces one cluster, so 35 new shoots, or 17-18 fruiting branches, are needed. Considering some damage may occur during earthing up and removing, about 20 fruiting branches can be retained per plant. These 20 fruiting branches are arranged in two layers (natural fan shape) on the trellis (2.0 meters apart), with 10 branches per layer, averaging one new shoot per 10 centimeters. If the variety has a strong fruiting ability, slightly fewer branches can be retained, and for varieties with lower fruiting branches, slightly more fruiting branches can be retained, with some dense vegetative branches removed later. The retained fruiting branches must be mature, well-grown, free of diseases and pests, and have space. For disease and pest branches, dense or crossing branches, and weak branches, they should be gradually and plannedly thinned out.
3. Branch Update
A. Fruiting Branch Update: Generally, double branch renewal and single branch renewal methods are used. Double branch renewal means that two fruiting branches form a branch group. In pruning, the upper mother branch is retained longer and removed after the fruiting year, while the base branch is retained shorter as a reserve branch. In the next year, one or two strong new shoots are trained on it, continuing the long and short pruning alternately every year to maintain a relatively stable number and position of fruiting branches. Single branch renewal does not retain a reserve branch, only pruning the two fruiting branches, and then selecting a new shoot from the base in the next year to continue as the fruiting branch, while the upper branches are completely removed. In production, single branch renewal is often used when pruning medium to short shoots, but when pruning medium to long shoots, attention should be paid to leaving a reserve branch at the base.
B. Old Vine Update: When the main and lateral vines of grapes show signs of weakness, baldness, pest damage, or necrosis, they need to be renewed. Appropriate branches can be selected from the suckers or adventitious branches at the base of the plant for preliminary training, and then the old vines to be renewed are gradually removed and replaced with new vines. Note that not too many large vines should be renewed at once, but this can be done year by year.
The above is a comprehensive explanation of how to prune grapevines for high yield and the pruning techniques for grapevines in winter, hoping it can help you.