First, fine fruit thinning: The process of artificial fruit thinning should start 7 to 10 days after flowering and be completed within a month after the flowers fall. Trees that flower early, have a high fruit set rate, poor fertilizer and water management, serious disease problems, heavy fruit load, or weak growth may require earlier thinning. On the other hand, varieties that flower later, have a low fruit set, heavier fruits, or lower productivity may benefit from delayed thinning. When thinning, it's important to select well-shaped fruits, leaving more on long branches and those growing downward. Remove small, diseased, deformed, or misshapen fruits, as well as those at the tips or with short stems that grow upward.
Second, fine bagging: (1) For early-maturing varieties like Tsugaru, Dora, and some U.S. apple types, bagging should begin 10 to 15 days after flowering. Red Fuji apples are best bagged 15 to 20 days after flowering, and this should be completed before mid-June. Full-bag cultivation is recommended for Red Fuji, using a combination of paper and plastic bags. Paper bags are ideal for areas with moderate light in the middle of the canopy, while plastic bags are better for the upper, lower, and outer parts. You can also use a two-step method—first applying a plastic film bag for 10 to 15 days, then covering it with a low-cost double-layer paper bag. This improves fruit quality. The paper bag application should generally be done by early July.
(2) Two to three days before bagging, apply insecticides and calcium fertilizers carefully. Focus on the fruit clusters, ensure high atomization, and spray thoroughly. During the bagging period, pay attention to controlling pests such as ringworm, brown spot, and calcium deficiency. The type and frequency of pesticide application depend on weather conditions. Typically, 3 to 4 applications are needed per season. In rainy years, spray amino acid calcium fertilizer 2 to 3 times. Add systemic fungicides like thiophanate-methyl, carbendazim, or bacterial clear. In dry periods, use protective fungicides like Taisheng or Bacteria. Also, manage pests like cotton bollworms, aphids, leaf miners, and caterpillars using agents such as pyrethroids, morphine, imidacloprid, diflubenzuron, Qi Qi Su, etc. After mid-June, when bagging is complete, spray a 1:2:200–240 Bordeaux mixture on the tree to prevent diseases like early defoliation and ring rot effectively.
Third, managing fertilization and irrigation: The fruit bagging period is a critical time for young fruit development. Proper nutrient and water management supports fruit growth and helps reduce sunburn. After flowering, trees with many flowers, heavy fruit sets, or weak growth should receive top-dressing with urea promptly. From late May to mid-June, apply 15% compound fertilizer containing nitrogen, phosphorus, and potassium, at a rate of 50–75 kg per mu. Combine this with foliar sprays like 0.3% urea or amino acid micro-fertilizer for better results.
Fourth, tree pruning:
(1) During mid to late May, avoid girdling main or branch trunks on apple trees like Zhuangwang, Fujia, and long-branched red Fuji. However, for varieties like Red Fuji and Red Star, if the tree is too vigorous, you can cut back every 10 days, even up to three times. For Wang Tzu, make 2–3 cuts at the base of the branches, spaced 2–3 cm apart in mid-May to slow growth and promote flower bud differentiation.
(2) Remove excessive and dense non-fruiting shoots, eliminate sprouts from large cuts, and upright any excessive shoots on the main branches. Avoid over-pruning in summer, as this can weaken the tree. For young saplings, from late April to early May, top the fruit-bearing shoots and shoots to improve fruit setting, especially effective for Zhuguang and Marshal varieties. For the Changfu No. 2 variety, from late May to early June, leave 20 cm of a single length on the fruit shoots, remove one of the two pairs, and keep the other 20 cm to encourage fruit development and increase yield.
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