What exactly causes grape berry cracking?
Grape berry cracking mainly occurs during the berry ripening stage. It is a physiological disorder of grapes, showing up as cracked skins. The exposed flesh lowers the commercial value, and after cracking, the juice leaks out and moisture is lost, which easily leads to dried fruit or attacks by pests and diseases, increasing losses. So do you know what causes grape berry cracking? Below, the editor brings you several major causes of grape berry cracking. Let's take a look.
1. Variety
Grapes come in many varieties, and different varieties differ in flesh firmness and skin thickness, so their ability to resist compression and cracking also varies greatly. For example, varieties such as Red Globe have firm, crisp flesh, evenly and tightly arranged berries, and relatively tough skins, so they resist compression well and are not prone to cracking; while varieties such as Kyoho and Ruby have soft flesh, uneven and loosely arranged berries, and a loose connection between flesh and skin, making them prone to cracking.
2. Improper water regulation
In the late growth stage of grapes, if the fruit encounters drought during the swelling period, and then meets cloudy and rainy weather or improper watering at maturity, the plant will absorb a large amount of water and transport it to the fruit, speeding up the cell activity and division of the flesh, while the cell activity of the skin is slower. This strong contrast causes the fruit's turgor pressure to surge, resulting in cracking.
3. Improper fertilization
Grapes need different nutrients during growth. If fertilization is too single or improper, it leads to unbalanced soil nutrients, seriously affects grape growth, and weakens the fertilizer and water regulation capacity of the planting, making the fruit highly prone to cracking during the swelling stage. Specifically, this shows up as blindly applying large amounts of nitrogen, phosphorus and potassium fertilizers while ignoring trace elements such as calcium, boron and zinc, causing soil nutrient imbalance and affecting growth; in addition, some farmers apply excessive nitrogen fertilizer, causing cracking during the fruit swelling stage.
4. Improper pruning
During planting, in order to promote more branching and increase the number of flowers and fruits, excessive pruning of branches and leaves weakens the plant's nutrient synthesis and water condition capacity, causing cracking. Generally speaking, when pruning, the secondary shoots above the fruit cluster can keep 1-2 leaves. And each normally growing fruiting branch should retain more than 25 leaves.
5. Pests and diseases
Damage from pests and diseases is also one of the main causes of grape berry cracking. For example, pests include thrips and green plant bugs, and diseases include powdery mildew and gray mold, all of which can cause grape berry cracking.
6. Improper pesticide use
In the process of grape cultivation, whether for pest and disease control or growth regulation, pesticides are used. These pesticides more or less stimulate the grapes, injuring the fruit surface and making cracking highly likely in the late growth stage.
The above is all the content on the causes of grape berry cracking. We hope it helps you. If you want to learn more about grape cultivation knowledge, please follow us.