What are the key points of autumn management techniques for plum orchards?
Autumn is an important period for plum trees to restore tree vigor and accumulate nutrients in the tree body. Applying scientific management measures can increase the reserve of tree nutrients, promote further differentiation of flower buds, and lay a good foundation for high yield and high quality in the following year. Through many years of practice, plum orchards where the management technique measures of this period are properly applied can all achieve high yield and high quality in the following year. The autumn management techniques for plum orchards are summarized as follows.
I. Fertilizer and water management
1. Foliar fertilizer spraying: After fruit harvest, spray 0.3-0.5% potassium dihydrogen phosphate once as early as possible to improve the nutrient accumulation of the tree body, promote leaf assimilation and branch filling, enhance tree vigor, and facilitate overwintering.
2. Application of base fertilizer: Apply base fertilizer from late August to early October. For the application rate, apply 20-30 kg of decomposed farmyard manure per tree at the initial fruiting stage; at the full fruiting stage, apply 30-50 kg per tree, together with 0.5-1.0 kg of urea and 1.5 kg of compound fertilizer (nitrogen : phosphorus : potassium = 15 : 12 : 15). Apply by the radial trench method, starting at 1/2 of the tree disk, with the outer end aligned with the outer edge of the tree canopy, dig 7-9 radial trenches, 30-40 cm deep and about 40 cm wide, spread the mixed fertilizer into the trenches, and then cover with a layer of soil. During this period of fertilization, the root system is at its growth peak, severed roots heal and grow easily, the fertilizer has sufficient time to rot and decompose, and the degree of mineralization is high. Some fertilizer can be absorbed and utilized by the tree body in the same year, promoting leaf assimilation, which helps produce and accumulate nutrients and meets the needs of plum trees for sprouting, flowering, fruit setting, and growth in the following year.
3. Irrigation: Irrigate the first water promptly after fruit harvest. The irrigation amount depends on soil moisture conditions, so that soil moisture is most favorable for plum tree growth and development. When irrigating, open trenches 20-25 cm deep between the rows in the plum orchard, with the trench direction preferably perpendicular to the water channel, and fill the trenches level promptly after irrigation. Thereafter, determine whether to irrigate according to soil moisture conditions; before the soil freezes, irrigate once with thorough water to enhance leaf photosynthesis, promote nutrient accumulation in the tree body, and facilitate overwintering of the tree body.
II. Soil plowing
Generally, from early September to early October, soil plowing is carried out in combination with autumn application of base fertilizer, with a plowing depth of 20-40 cm. During this period, aboveground plant growth is slow, assimilation product consumption is relatively low, and backflow accumulation has already begun. Therefore, plowing soil during this period coincides with the 2nd or 3rd root growth peak of plum trees, wounds heal easily; at the same time, new roots are easily produced, which is beneficial for absorbing and synthesizing nutrients, increasing tree body accumulation, and benefiting growth and development in the following year. In addition, after plowing during this period, going through the long winter is beneficial for soil weathering and improves soil permeability. It can also eliminate underground pests and eradicate perennial weeds and root suckers.
III. Tree body management
1. Tree cleaning: Pick all diseased and insect-damaged fruits remaining on the trees and bury them deeply in a centralized manner; remove root suckers sprouting from the root crown.
2. Orchard cleaning: Remove aboveground weeds and fallen leaves and dead branches, and clear them out of the orchard or burn them in a centralized manner to reduce the base number of overwintering disease and insect sources.
IV. Training and pruning
After fruit harvest, carry out pinching and branch thinning in combination with tree cleaning. Pay attention to selecting and retaining strong branches in suitable positions, remove weak, diseased and insect-damaged, densely growing, drooping, and overly dense water sprouts in the inner canopy, and pinch the reserved branches. Improve ventilation and light transmission conditions of the tree body to facilitate branch filling and overwintering of the tree body, and also lay a foundation for winter pruning.
V. Disease and pest control
To protect leaves, and at the same time to reduce disease sources and lower the overwintering base number of pests, in autumn the trees can be sprayed with 50% carbendazim 800-1000 times solution, or thiophanate-methyl 800-1000 times solution, or 80% mancozeb 800-1000 times solution, or 50% thiram 800 times solution; to control hawthorn red spider, 40% dicofol emulsifiable concentrate 1500-2000 times solution can be used; to control plum fruit moth and others, 2.5% deltamethrin 3000 times solution can be used, or 50% phoxim 800 times solution + 40% omethoate 800 times solution, or 20% fenvalerate 3000 times solution.
VI. Overwintering protection
Before the soil freezes, whitewash the tree trunks (add an appropriate amount of fungicide to the whitewash agent) to protect the tree body for safe overwintering.