What to Do About Uneven Grape Coloration? Causes and Fertilizing and Watering Methods During the Veraison Stage
Luan Guojun encountered a strange thing at home during the grape ripening period. The grapes in his vineyard, for some unknown reason, were green in some places, red in others, and purple in still others, truly a riot of colors and endless variety. Is this related to grape growing methods? Watching the
Luan Guojun encountered a strange thing at home during the grape ripening period. The grapes in his vineyard, for some unknown reason, were green in some places, red in others, and purple in still others, truly a riot of colors and endless variety. Is this related to grape growing methods? Watching the grapes of other farmers being bought by grape merchants and hauled away by the cartload, while his own grapes never reached the standard for ripeness and could not be sold, and even when the occasional peddler entered the vineyard, one look at his grapes with uneven coloration all over the vineyard and they would just smile, turn around, and walk away. This left Luan Guojun feeling very upset.
Later, he invited the agrochemical staff from the local agricultural technology station to inspect on site, and only then did he learn that it was excessive nitrogen fertilizer application that had caused the grapevines to grow excessively, making the fruit trees grow greedily and ripen late, affecting the normal ripening and coloration of the grapes.
In response to the uneven grape coloration, the agrochemical staff also offered Luan Guojun several management suggestions:
1. Branch and leaf pruning
Lush branches and leaves and shading in the orchard can cause poor light penetration and aeration in the vineyard, affecting the normal coloration of grapes and the increase of sweetness. The branches and leaves of the tree body should be pruned according to the actual condition of the fruit trees, promptly removing dense branches and old leaves that block light, so as to provide grapes with sufficient sunlight and air circulation space.
2. Fruit thinning and yield control
More fruit on the tree is not necessarily better. If the tree body bears too heavy a load, it will affect the supply of normal nutrients and easily cause difficulty in grape ripening and coloration. Therefore, fruit clusters and small clusters that bear too much fruit or have poor appearance should be thinned and removed in a timely manner, so as to ensure the normal nutrient requirements for grape coloration while maintaining yield.
3. Scientific fertilizer use
Potassium and phosphorus are nutrients that grapes need in relatively large amounts for growth. They should be supplemented in a timely manner one month before the ripening stage to provide energy for the fruit trees, promote anthocyanin accumulation, and improve grape coloration. In the later stage, nitrogen fertilizer should be applied sparingly or not at all. Excessive nitrogen fertilizer application will cause excessive growth of branches and leaves and delayed ripening due to greed for green growth, affecting the ripening and market time of grapes.
4. Water control
During the grape ripening period, a relatively dry environment makes it easier to increase sugar content and coloration, so orchard water use should be moderately controlled, but do not control water excessively.
5. Growth vigor management
Manage the growth vigor of the fruit trees well; moderately vigorous fruit trees color most easily. If the fruit trees grow too vigorously, nutrients tend to be transferred to the branches; if the tree vigor is too weak, nutrients tend to be insufficiently supplied, both of which affect the normal coloration of grapes.
6. Plastic film reflection
To better help grapes color, plastic film can be laid on the ground at the base of the grapevines, using the reflective effect of the plastic film to help the grapes color more evenly.
Do the grapes you grow ever show this phenomenon? Next time you encounter such a situation, you can adopt the methods above.
Do the grapes you grow ever show this phenomenon? Next time you encounter such a situation, you can adopt the methods above.
