What are the key management points for apple trees in August?
August is the flower bud differentiation period for apple trees and the fruit enlargement period for mid-to-late ripening varieties. During this period, photosynthesis is intense and photosynthetic accumulation speeds up accordingly. In addition to vigorous new shoots continuing to grow faster, most new shoots gradually stop growing from slow growth, and absorption roots are produced in large numbers, with water and nutrient absorption and utilization also speeding up accordingly. Therefore, strengthening management during this period plays an important role in improving the quality of flower bud differentiation and fruit quality. The specific measures are as follows:
1. Pruning. In early August, short-tip prune the vigorous shoots of young trees to promote the growth of secondary lateral shoots, which can form flower buds in the same year, achieving the goal of more flowers and early high yield. In addition, pruning during this period also has obvious effects on branch group cultivation and canopy control. The cutting position should preferably leave 3-5 leaves at the base of the spring shoot. In early August, for large trees with too many auxiliary branches, some large branches can be thinned out, and water sprouts, upright branches and overly vigorous branches should also be thinned as space permits, to improve ventilation and light penetration conditions of the tree body and improve flower bud quality. In early August, bend and open the angle of one-year-old long branches, injuring the xylem of the new shoot segment, causing the branch tissue to be damaged and droop or become horizontal, so as to suppress apical growth dominance, promote the sprouting of secondary lateral shoots, and increase the amount of branches and leaves of young trees. In late August, branches are relatively soft, and after the angle is opened, water sprouts are not easily produced on the back of the branches, making it a good time to pull and open the angle of scaffold branches and large auxiliary branches. Before young trees take shape, persist in pulling branches every year. When pulling branches to open the angle, never pull them into a bow shape, so as to avoid producing vigorous branches on the back.
2. Soil, fertilizer and water management. In early August, in combination with pesticide spraying, spray the foliage with 0.3% urea + 0.5% potassium dihydrogen phosphate solution to promote new shoot maturity and improve cold resistance. Spray once more after 10 days to enhance fruit coloring and increase sugar content. For orchards with bitter pit disease, in early August continuously spray 0.5%-1% calcium chloride 2-3 times, mainly spraying the fruit, which can increase flesh firmness and improve storage tolerance. In mid-August, autumn shoots gradually stop growing. Applying compound fertilizer can prevent leaves from aging prematurely, promote nutrient accumulation in the tree body, restore tree vigor, facilitate flower bud differentiation and fruit enlargement, and help increase the fruit-setting rate the following year and increase new shoot growth. During this period, watering in combination with topdressing has a good effect on increasing yield, enhancing coloring and improving quality. After watering or rain, timely carry out intertillage and weeding. Young orchards can be deep plowed to a depth of about 20-30 cm to thoroughly remove weeds and promote root growth.
3. Fruit management. For bagged fruit of mid-ripening varieties, remove the bags starting from mid-to-late August. For double-layer bags, first remove the outer bag, and remove the inner bag 3-5 days later; for single-layer bags, first tear open the bottom of the paper bag, leave the remaining bag on the fruit, and remove it 3-5 days later. Note to choose a time of day when the temperature difference inside and outside the bag is small for bag removal. After bag removal, carry out leaf removal, fruit turning and reflective film laying to promote comprehensive fruit coloring. For Marshal series varieties that are prone to fruit drop before harvest, spray 30-40 mg/kg naphthaleneacetic acid once each in mid-August and at the end of August, that is, one month and half a month before harvest, to prevent pre-harvest fruit drop.
4. Pest and disease control. Continue to investigate and treat valsa canker. Alternately use 1:2-3:200 Bordeaux mixture, 50% iprodione wettable powder 1000-1500 times solution, and 50% mancozeb wettable powder 500 times solution to control anthracnose, ring rot, alternate leaf spot and other diseases. Remove diseased fruit promptly when found and bury it deeply. Use 25% chlorbenzuron No. 3 2000 times solution to control Lepidoptera pests such as golden leafminer and apple small leafroller. In late August, tie grass bundles on tree trunks to attract overwintering pests such as red spiders. Remove and burn them before thawing the following year to reduce pest population density. When checking fruit after bag removal and finding Konishi mealybug larvae, spray 52.25% chlorpyrifos 1500-2000 times solution on the trees to control their damage.
Song Suzhi, Chai Quanxi, Vocational Education Center of Gaocheng District, Shijiazhuang City