Sunburn is a kind of fruit disease caused by physiological maladjustment such as strong light, high temperature etc, which occurred in most deciduous fruit trees. So, why do grapes have sunburn symptoms?

1. Local Water Shortage:

l The fruit is under the high temperature condition without shade of leaves

l Leaves with high osmotic pressure compete for water from fruits with low osmotic pressure

The above reasons can be obtained that, the grapes are partially dehydrated and finally sunburned.

2. Uneven Fertilization:

Uneven fertilization ->unbalanced root nutrition of grape plants ->poor growth and tree vigor of grapes ->small and few leaves ->reduced resistance to sunlight ->fruit burns

3. Fruit Bagging Time Error:

When bagging time is too late or the temperature is too high, it will aggravate sunburn.

4. Improper Pruning of Grape plants:

Excessive pruning of branches makes the fruit pedicle unable to receive proper shade，which is prone to sunburn.