Detailed Explanation of the Causes of Grapevine Bleeding and Control Methods
During growth and development, grapevines exhibit a phenomenon known as bleeding, which refers to the outflow of transparent sap from fresh wounds on the vines or root system. In mild cases, this causes weakened vine vigor and flower and fruit drop, leading to reduced yields; in severe cases, it can cause the plant to wither and die. So what causes grapevine bleeding? How should it be controlled? Let's take a look.
I. Causes of Bleeding
1. Pruning too late
When fruit growers prune too late, bleeding often occurs. This is especially pronounced when pruning after Awakening of Insects (Jingzhe), and as temperatures rise, the severity of bleeding worsens. If thick large canes are pruned, it can often cause the plant to die.
2. Mechanical damage
Winters in the north are cold, often below 0°C, so when growing grapes in the north, the method of burying vines in soil for cold protection is often adopted to ensure they survive the winter safely. But in spring, as temperatures rise, improper handling when unearthing the vines often causes damage to the root system, making bleeding highly likely.
3. Root damage from fertilization
After the beginning of spring, temperatures rise, and at this time, in order to help fruit trees recover vigor as quickly as possible, promote budding, and produce more flowers and fruit, fruit growers fertilize the plants. But grapes are exactly the opposite: fertilizing them in spring causes weakened vine vigor, reduced yields, and in severe cases total crop failure. So at the beginning of spring, be sure not to fertilize, to avoid fertilizer burning the roots and causing bleeding and death.
II. Control Methods
1. Prune at the right time
To prevent bleeding, grapevines should ideally be pruned after leaf fall, and at the latest before Awakening of Insects (Jingzhe); otherwise bleeding will occur. When pruning, also take care not to prune thick large canes, to avoid wounds that are too large and difficult to heal, which would cause bleeding.
2. Prevent damage when unearthing
When unearthing vines in spring, be careful and cautious. When approaching the root zone soil, use your hands to dig as much as possible, to avoid mechanical damage from even slight mishandling.
3. Change fertilization habits
When fertilizing, avoid the grapevine bleeding period, that is, February to March. If fertilization is needed, try to choose mid-to-late April. At this time, try to choose organic fertilizer as the base fertilizer, and apply fully decomposed organic fertilizer deeply, which can help the plant rapidly accumulate nutrients and prepare for later growth and flowering and fruiting.
4. Protect wounds
Protecting wounds is the best way to prevent bleeding. After pruning, white latex or pruning seal oil can be applied to the wounds, which can reduce the chance of bleeding. According to practical production experience, wounds without protective coating have a bleeding rate of 50%, while protected wounds are only 10%-20%, and this method is convenient, quick, and extremely low-cost.
The above are the causes of grapevine bleeding and control methods. We hope this helps you. To learn more about grape growing, please follow us.