What management measures are there for bagged fruit after the bags are removed?
Watering. Watering before bag removal not only promotes fruit enlargement but also has two other effects: one is to reduce sunburn of the fruit after bag removal, and the other is to change the orchard microclimate conditions, increase the day-night temperature difference, create night dew, and help fruit coloring (you can also spray water over the whole orchard in the evening during the fruit coloring period). Water 2 to 3 days before bag removal, and afterward water timely according to drought conditions. The amount of water should not be too large, keeping the soil moisture content at about 60% of the field maximum water-holding capacity.
Bag removal time. Red Fuji apples are removed from their bags about 30 days before harvest, generally from late September to early October. It is best to remove the bags on cloudy or partly cloudy days to avoid sunburn of the fruit after bag removal. If removing bags on a hot sunny day, do so after 10 a.m. when the fruit surface temperature is close to or slightly higher than the air temperature. Do not remove bags in the early morning or evening.
Fruit padding at the same time as bag removal. The purpose of padding the fruit is to prevent the branches and leaves from rubbing against the fruit surface after bag removal. The removed waste bags can be used to pad the parts of the fruit surface close to the branches. Remove branches that are likely to puncture the fruit surface before bag removal.
Leaf removal and fruit turning. After bag removal, remove leaves and turn the fruit timely according to the coloring condition of the fruit. Fuji apple coloring mainly depends on direct light, and coloring is poor under diffused light conditions. Therefore, after bag removal, promptly remove the branches and leaves that affect fruit coloring, and while removing leaves, turn the shaded side of the fruit toward the sunny side to produce fully red fruit. Be careful during operation to avoid twisting off the fruit. The total amount of leaf removal should be controlled at 10% to 15%, and must not exceed 20%. Do not remove leaves at noon under blazing sun, to avoid sunburn of the fruit. The time should be chosen on a cloudy day, or after 3 p.m. on a sunny day.
Foliar fertilizer spraying. After Fuji apples are bagged, because the temperature inside the bag is high, calcium metabolism is strong, and calcium has low mobility in the tree, compared with unbagged fruit, calcium deficiency is more likely to occur, causing bitter pit. After bag removal, the fruit is in the near-ripening stage, which is another peak period for calcium absorption. Therefore, spraying calcium fertilizer 2 to 3 times promptly after bag removal can reduce the occurrence of bitter pit. Various amino acid calcium fertilizers can be selected. In addition, to promote fruit coloring, combined with calcium supplementation, spray 200 to 300 times potassium dihydrogen phosphate on the leaves 2 to 3 times.
Disease prevention and fruit protection. Red spot disease and ring rot can infect the fruit after bag removal, causing red-brown lesions of 1 to 2 mm on the fruit surface, reducing the rate of good fruit and affecting the selling price. The control method is: start spraying the whole tree 5 days after bag removal. The pesticide should be a powder or aqueous preparation that is therapeutic and does not irritate the fruit surface, such as: 70% imported thiophanate-methyl or domestically produced pure thiophanate-methyl 1000 times solution, or 80% pure carbendazim powder 1000 times solution, etc.