What are the causes of grape berry cracking? Master these 6 points to protect your yield

Grape berry cracking mainly occurs during the ripening stage. Different varieties also differ in the degree of cracking. Excessive fertilization and improper water regulation can both cause cracking. Of course, over-pruning grapevines can also cause cracking. Therefore, during the growing process, pest and disease control must be done well, and grape cultivation management should be strengthened.

Cause 1: Variety issues

There are many grape varieties, and because the varieties differ, the degree of cracking also differs. For example, varieties such as Ruby Seedless and Kyoho have relatively soft berries, grow unevenly and are loosely arranged, and the flesh and skin do not connect tightly enough, making them prone to cracking. Varieties such as Red Globe, however, have firm, thick flesh and good skin elasticity, so they have strong pressure resistance and are not prone to cracking.

Cause 2: Fertilization too one-sided

During the grape growing period, fertilization should not be too one-sided; different nutrients are needed to meet its growth requirements. When fertilizing, be careful not to overapply. By the grape ripening stage, when the berries are expanding, do not excessively apply nitrogen-phosphorus-potassium fertilizer and nitrogen fertilizer, as this will also cause soil nutrient imbalance, affect growth, and lead to grape berry cracking. Be sure to supplement trace elements such as boron, calcium, and zinc.

Cause 3: Water not controlled well

During the grape ripening stage, if the expanding berries encounter drought, and then rainy weather occurs at maturity, excessive watering will cause the grapevine to absorb a large amount of water and transport it to the berries, making the flesh split too quickly while the skin expands more slowly, creating a strong contrast, causing excessive turgor pressure in the berries and resulting in cracking.

Cause 4: Improper pruning

During the growing process, to increase berry yield, branches and leaves are pruned. It is best to leave about 2 leaves on the secondary shoots above the fruit cluster, while normally growing fruit-bearing branches should retain about 25 leaves. If branches and leaves are pruned excessively, the plant's nutrient synthesis and water regulation capacity will weaken, causing cracking.

Cause 5: Impact of pests and diseases

In the later stage, pest and disease control on grapes must be done well. For example, pests include green leafhoppers and thrips, and diseases include gray mold and powdery mildew. All of them can cause grape berry cracking.

Cause 6: Improper use of chemicals

In the process of growing grapes, chemicals are used for pest and disease control and to promote growth, and these chemicals generally affect grape growth, causing cracking on the grape surface, and the likelihood of cracking occurring later will also be greater.