A Detailed Explanation of the Causes of Grapevine Bleeding and Its Prevention and Control Methods
During growth and development, grapevines exhibit a phenomenon known as bleeding, which refers to the outflow of transparent sap from new wounds on the vines or root system. This phenomenon, in mild cases, causes weakened tree vigor, flower and fruit drop, leading to reduced yield; in severe cases, it causes the plant to wither and die. So what causes grapevine bleeding? How should it be prevented and controlled? Let's take a look together.
I. Causes of Bleeding
1. Pruning too late
When fruit growers prune too late, bleeding is often triggered, especially when pruning after Awakening of Insects (Jingzhe), when bleeding tends to be more severe. As temperatures rise, the degree of bleeding worsens, and pruning thick large branches and vines often causes the plant to die.
2. Mechanical damage
Winters in the north are cold, often below 0 degrees, 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. However, in spring as temperatures rise, improper operation when unearthing the vines often causes damage to the plant's root system, very easily leading to bleeding.
3. Fertilization damaging roots
After the beginning of spring, as temperatures rise, in order to help fruit trees recover their vigor as quickly as possible, promote budding, and encourage more flowering and fruiting, fruit growers apply fertilizer to the plants. But grapes are exactly the opposite: applying fertilizer in spring causes weakened tree vigor, reduced yield, and in severe cases total crop failure. So at the beginning of spring, be sure not to fertilize, to avoid fertilizer scorching the root system and causing bleeding and death.
II. Prevention and Control Methods
1. Prune at the right time
To prevent bleeding, grapevines are best pruned after leaf fall, and at the latest before Awakening of Insects (Jingzhe), otherwise bleeding will occur. Pruning also requires attention: it is not advisable to prune thick large branches and vines, to avoid wounds that are too large and difficult to heal, thereby causing bleeding.
2. Prevent damage when unearthing
When unearthing the vines in spring, be careful and cautious. When approaching the root zone soil, try to dig with your hands, to avoid mechanical damage caused by slight carelessness.
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 buried, which allows the plant to quickly accumulate nutrients and prepare for later growth, 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 evidence, 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 in cost.
The above are the causes of grapevine bleeding and its prevention and control methods. We hope this helps you. To learn more about grape growing knowledge, please follow us.