What causes grape drop

Grape shedding may be caused by poor pollination, nutritional imbalance, infection by pests and diseases, improper water management, mechanical damage, and other reasons.

1. Poor pollination

During the flowering period of grapes, continuous rainy or low-temperature weather can lead to a decrease in pollen activity, affecting normal pollination. The ovary that has not been successfully pollinated will stop developing, form weak fruits, and fall off during the swelling period. It can be improved through manual pollination or planting pollination trees.

2. Nutrient imbalance

Excessive nitrogen fertilizer can cause branches to grow excessively and compete with fruits for nutrients; Calcium deficiency can lead to fragile cell walls in fruit stalks; Insufficient potassium element affects sugar transport. It is recommended to increase the application of phosphorus and potassium fertilizers during the flowering period, supplement calcium fertilizers on the leaves during the young fruit stage, and control the amount of nitrogen fertilizer used.

3. Infection of pests and diseases

Gray mold infection on fruit stalks can form abscission, powdery mildew can damage leaves and weaken tree vigor, and thrips biting fruit stalks can lead to fruit drop. In the early stages of the disease, azoxystrobin can be used to control gray mold, tebuconazole can control powdery mildew, and efficient chlorpyrifos can be used to kill thrips.

4. Improper water management

Sudden drought during the expansion period will cause the fruit stalk to separate from the layer, and water accumulation after rainstorm will inhibit root respiration. Soil moisture should be kept stable, with frequent watering with small amounts of water during droughts, timely drainage during rainy seasons, and appropriate water control during color changing periods to promote sugar accumulation.

5. Mechanical damage

Scratches from strong winds can cause damage to the skin of the fruit stem, collisions with fruits during agricultural operations, and external forces such as bird pecking can directly lead to grain falling. Can build a bird proof net, prune overly dense branches to improve ventilation, and preserve strong fruit clusters when thinning.

Comprehensive management is required to prevent grape shedding. During winter cleaning, diseased and residual bodies should be thoroughly removed, and stone sulfur mixture should be sprayed for sterilization before sprouting. Keep the shelf surface ventilated and transparent during the growth period, regularly check for pests and diseases, and supplement foliar fertilizers containing amino acids during fruit development to enhance stress resistance. Stop using pesticides 20 days before harvesting to avoid excessive pesticide residues. Reasonably control yield, it is advisable to retain 2000-2500 ears per acre, as excessive fruit hanging will exacerbate physiological grain loss.