1. At the early stage of grape fruit growth, the soil was too dry. After entering the coloring stage, if there is sudden heavy rain or large amount of irrigation, the soil water content will increase sharply, the root system will absorb a lot of water, and the pressure of fruit expansion will increase, leading to peel cracking.
2. In the later stage of fruit development, if the weather is dry, the vineyard will be heavily irrigated many times, and the soil water content will change dramatically. If the cultivated grape is a variety with too tight fruit grains, the fruit grains will squeeze each other, and the cell division near the pulp will be accelerated, while the cell activity near the peel will be slow, and the pressure of fruit expansion will increase, resulting in grape cracking.
3. Grape plants have too many branches and vines, the total leaf area is too large, the shelf surface is dark, and the ventilation and light transmission are poor; If there are too many grains per ear, the leaf area is relatively small, and the water metabolism between the leaf and the fruit is unbalanced, the fruit will be thin and brittle and easy to crack when it matures.
4. If pesticides, such as fungicides, are sprayed continuously to prevent grape diseases, transpiration water will be reduced, and a large amount of water in the tree will flow to the fruit, which will increase the pressure of fruit expansion and lead to fruit cracking.
5. Strong wind and hot weather in young fruit period can also lead to grape cracking.
6. Use ripening agents, such as ethephon and abscisic acid. If the pesticide concentration sprayed is too high or sprayed too early, it will often lead to grape cracking.
Measures to prevent grape from cracking
1 to prevent soil moisture imbalance. Pay attention to timely irrigation when the soil is dry, and timely drainage after rain to reduce the difference between dry and wet soil.
2. In case of drought in the later stage of fruit development, a small amount of irrigation is needed for many times to prevent flooding and avoid fruit swelling and cracking caused by drastic changes in soil water content.
3. For the new shoots with fruit, it should be changed from pre-flowering to post-flowering, so as to make them drop fruit properly, or thinning some spikelets before flowering, so as to make the ear elastic and reduce the mutual extrusion of fruit grains to form cracked fruit.
4. Adjust the load by thinning branches and ears. Keep the leaf-fruit ratio15-20:1; Strong vine leaves 2 ears, medium vine leaves 1 ear, and weak vine leaves no ear.
5. Wipe off or cut off the secondary ear in time and pinch the tip of the ear to make the ear grow moderately.
6, timely prevention and control of leaf diseases and insect pests, the annual growth cycle should not be more than 3 times.
7. Build windbreaks to prevent strong winds. If you encounter high temperature in the young fruit period, you can irrigate the orchard or spray water on the fruit trees before the high temperature comes.
8. Use ethephon and abscisic acid ripening agent. The suitable concentration of ethephon is 500mg/kg and abscisic acid is 100 mg/kg, which must be used when the fruit is 5- 10% colored.
10, the second fruit expansion stage, with 500 ml/kg rare earth, spray 1 time every 7- 10 days, and spray twice continuously. When preparing, firstly, adjust the water into a slightly acidic solution (pH 5-6) with vinegar, then add rare earth, and spray it when it is cool in sunny days.