How to Prune Northern Grapes
Growers of northern grapes often suffer reduced yields due to improper pruning. Scientific pruning techniques directly affect fruit quality and vine health. Mastering the timing and key points of winter pruning is crucial for achieving high-quality and abundant yields.
Key Points of Northern Grape Pruning Techniques
Pruning Length Control Principle
Judge the retained length based on the growth of the branches, the position of the flower buds, and the fruiting branch rate. Strong branches should be retained 30% longer than weak ones. Extension branches are usually retained with 8-12 buds, while reserve branches have 2-3 buds. In dry areas, it is recommended to use the short shoot pruning method, retaining 3-5 effective bud eyes.
Pruning Cut Techniques
The correct cut should be 2.5-4 centimeters away from the bud eye, forming a 45°斜面 (oblique cut). Pay attention to keeping the cut perpendicular to the direction of the bud eye to avoid the sap directly washing the bud. It is recommended to use a sharp pruning shear that has been disinfected to ensure a smooth and stubble-free cut.
Bud Retention Calculation Formula
Set the base number of retained buds according to the type of trellis: 25-35 effective buds per square meter for篱架 (fence trellis), and 18-25 for棚架 (awning trellis). The actual number of buds retained should have a 50% redundancy, for example, if the target is 20 new shoots, 30-40 buds should be retained in winter to account for winter frost and spring sprout loss.
Controlling the Timing of Winter Pruning for Grapes
The best pruning period is 2 weeks after defoliation to 20 days before the soil freezes, with the focus in the north being from late October to mid-November. For greenhouse cultivation, pruning should be completed 10 days before covering with film. Field cultivation should pause operations when temperatures drop below -5°C. Special care should be taken to avoid the bleeding period to prevent the loss of sap that can weaken the plant.
Scientific pruning requires adjusting the plan based on tree age: for 3-year-old young trees, focus on training the main vine, retaining 6-8 fruiting mother branches; for plants in full fruiting stage, focus on updating the fruiting branch groups, replacing 30% of old branches each year. After pruning, promptly apply wound protectant and take winter irrigation and frost prevention measures to lay the foundation for abundant yields next year.