Bagging apple orchards should be harvested at the right time in the fall, with proper post-harvest management to ensure consistent high yields year after year. Effective bagging techniques and careful handling during removal are essential for maximizing fruit quality and reducing disease risks.
**1. Watering Before Bag Removal**
Watering before removing fruit bags serves two important purposes: it helps reduce sunburn on fruits after the bags are taken off and improves the microclimate in the orchard. This creates a greater temperature difference between day and night, promoting better fruit coloring. You can also spray water in the evening during the coloring period. The watering should occur 2–3 days before bag removal, with soil moisture maintained at around 60% of the field’s maximum holding capacity.
**2. Timing for Bag Removal**
For Red Fuji apples, bags should be removed about 30 days before harvest, typically from late September to early October. It's best to remove them on cloudy days or in the early morning to avoid sunburn. If you must remove bags on a sunny day, do so around 10 a.m., when surface temperatures are close to or slightly higher than ambient air temperature. Avoid removing bags in the early morning or late afternoon.
**3. Protecting Fruits During Removal**
To prevent leaf rub on the fruit surface, use the removed bags to cover nearby fruit. Also, remove branches that might puncture the fruit before bag removal to protect the fruit.
**4. Leaf Picking and Fruit Turning**
After removing the bags, prune leaves that block sunlight to improve fruit coloration. When picking leaves, gently turn the shaded side of the fruit to the sun to enhance redness. Be careful not to damage the fruit. Limit leaf removal to 10–15%, no more than 20%. Avoid doing this during midday when the sun is strongest to prevent sunburn. Choose cloudy days or after 3 p.m. for this task.
**5. Foliar Spraying for Nutrition**
After bag removal, it’s crucial to apply calcium fertilizer 2–3 times to prevent bitter pit disease, which is common in bagged apples due to reduced calcium absorption. Amino acid-based calcium sprays work well. To further support color development, spray potassium dihydrogen phosphate (200–300 times dilution) 2–3 times as well.
**6. Disease Prevention After Bag Removal**
Fruit diseases such as red spot and rosy ring can appear after bag removal, causing unsightly lesions. Begin spraying fungicides 5 days after bag removal. Use products like 70% carbendazim or 80% mancozeb at 1000 times dilution, ensuring they don’t irritate the fruit surface.
**Post-Harvest Management**
**1. Immediate Nutrient Replenishment**
After harvesting, spray the entire orchard with urea and potassium dihydrogen phosphate (both at 200 times dilution). Apply 2–3 times with a 5–7 day interval to restore tree vitality.
**2. Autumn Base Fertilization**
Apply organic and fast-acting fertilizers from mid-September until the ground freezes. Organic options include well-decomposed animal manure, with at least 3 m³ per 667 m². Use ring trenches or strip ditches, digging 20–30 cm deep. Fast-acting fertilizers, rich in trace elements, should make up over 60% of annual applications to avoid spring fertilization.
**3. Pest and Disease Control**
This is a critical time to control pests and reduce overwintering populations. Focus on controlling apple aphids, which are still active after harvest. Prune heavily infested branches and wrap wounds with plastic film to suffocate insects. Spray insecticides like Lethburn (1,500 times) or chlorpyrifos (1,000 times). For apple codling moths, target nymphs in early October using imidacloprid or chlorpyrifos. Clean up diseased branches, remove dead wood, and burn all debris to prevent disease spread. Protect any cuts or wounds with appropriate treatments.
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