Second, the characteristics of branches and buds
The branches of pear trees are crisp and hard, and the big branches are easy to split and break if they open corners or bear too many fruits. The classification and standards of branches are basically the same as those of apple trees, which are divided into foliage branches (< 0.5cm =, short branches (0.5-5.0cm), middle branches (5- 15cm), long branches (15-30cm) and flourishing branches (> 30cm). Most varieties bear fruit with flower buds at the top of short branches, and a few varieties bear fruit with flower buds at the axils of medium and long branches. In terms of tree age, young trees have medium and long branches, and big and old trees are rare. The flower buds are mixed buds, mainly the top flower buds, and the axillary flower buds are mostly inferior to the top flower buds. Flower buds are obviously larger than leaf buds and easy to identify. Flower buds are easier to form than apple trees, and they are earlier and more concentrated in time. Most of them form in June-July, and blossom and bear fruit in the next spring. Short branches generally have no axillary buds, so they should be kept sparsely and not cut. The 3-5 nodes at the base of medium and long branches are blind nodes, which are not suitable for heavy and short cutting, but there are more secondary buds on both sides of the base. Secondary buds generally do not germinate for a period of time, forming latent buds. Latent buds have long life and are easy to germinate when stimulated, which is beneficial to the regeneration of old branches. Therefore, apart from high germination rate, weak branching ability and obvious apical advantage, pear tree branches have two important characteristics: first, there are fewer dead buds at the base of branches and more secondary buds; Second, the latent buds are mostly transformed from secondary buds, and the latent buds formed by lateral buds are less.
Third, growth and fruiting habits
Pear trees first spread their leaves and then bloom in spring. However, unlike apples, in the same inflorescence, the marginal flower blooms earlier than the central bloom, and the fruit is better. The long branches of pear trees are mostly composed of spring shoots and summer shoots, with few autumn shoots. In spring and summer, the buds are full and the germination rate is high, but the included angle between the buds in spring is large and that between the buds in summer is small. These characteristics should be taken advantage of when pruning. The leaves on the new buds are dim when they are young.
After the maximum stop of growth, it appears bright and shiny, which is called bright leaf stage. The bright leaf stage shows that 85% of the leaves have been formed throughout the year, and the nutrition of the tree changes from consumption to flower bud differentiation at the terminal buds of short and medium branches. Except for special circumstances, pear trees rarely have secondary branches. The apical dominance and vertical dominance of branches are very strong, and the growth of single branches on the same parent branch is very different. After the straight branches are cut short, the top-down branches become shorter and shorter, and there are few competing branches. If the terminal bud extends in a single line without cutting, there are few branches. Oblique branches tend to grow long branches at the bend height, long branches at the top and back, and short branches at other parts. Pear branches have high germination rate and weak branching ability, and are easy to form short branches and middle branches, especially the branches grow fast in the early stage and stop growing early, and the terminal buds and lateral buds are full and full, which is beneficial to flowering and fruiting. Therefore, as long as pear trees have sufficient fertilizer and water, they are easy to bear early fruits and yield more. Pear trees have pollen allelopathy, and pollinated varieties will not change the shape and quality of fruits. The differentiation of long and short branches is obvious and the transformation ability is weak. The fruit branches at the lower part of the branches tend to weaken and form short fruit branches. If the branches over 6 years old are not renewed and rejuvenated in time, the fruiting ability will soon decline. At the same time as the fruiting branches blossom and bear fruit, the fruit surface can germinate secondary branches, which bloom in the same year and continue to bear fruit in the next year. The number and length of auxiliary shoots on the fruit surface often vary from variety to variety, and most varieties are easy to form short fruit branches with "chicken feet". Pear trees have the characteristics of heavy flower drop and light fruit drop, and less fruit drop in the later stage.
Growth characteristics of pear trees and pruning methods in summer
1. Growth characteristics of pear trees
1。 The growth period of pear trees is short and has obvious stages. The length will stop before July, and the medium and short length will stop before the first half of May. 2。 Pear leaves have the characteristics of fast growth and early leaf area formation. The medium and short leaves stopped growing in mid-May, and the total leaf area accounted for more than 85% of the whole tree. After the end of May, the increase of leaf area mainly depends on longer leaves. 3。 The branches of pear trees are very erect, and the contradiction between the growth of new branches (including auxiliary branches of fruit table) and the growth and development of young fruits on nutrients is more prominent in a short time. At the same time, the advantages of new shoots and back shoots are strong, while the growth potential of branches is weak. In production, the treatment of main branch angle and fruiting branch group angle is very sensitive to fruit growth and crown expansion.
Two. Principles of pruning in summer
1。 The cutting time in summer should not be too early, and the growth will basically stop in the short and medium term. The leaf area of the tree should reach more than 85% of the whole tree, that is, it is better to cut it in the middle and early May. Supplementary pruning will be carried out in June and July. 2。 Pruning is to improve the ventilation and light transmission conditions of the orchard on the basis of maintaining the original crown and the number of branches and leaves, and under the conditions of stable tree growth and balanced growth. The pruning amount shall not exceed 5%-65,438+00% of the total leaf amount, and the illumination rate under crown projection shall reach 20%-30%. 3) Pruning in summer focuses on adjusting the growth balance. According to the tree structure and orchard density, the balance relationship between the growth of young fruits and the growth of new fruits (including auxiliary fruits on the fruit table) should be handled well.
3. Cutting method in summer
1。 Sparse branches. Sparse cuttings, sawn branches, and long, medium and short buds sprouting on the back, top and holes. Try not to pick tips or cut short all kinds of long, medium and short buds that are growing or stopping growing. By thinning branches, the purpose of improving ventilation and light transmission of trees and reducing ineffective consumption of nutrients is achieved. At the same time, it should be noted that in order to keep the balance of the tree, the thinning of the back branches should not exceed 1/3- 1/2. 2。 Twist it a little. It is mainly aimed at the upright flourishing fruit surface, so it is not suitable to take the treatment of core removal or drying, which takes up the space of twisting branches and throwing branches, so as to promote the growth of auxiliary leaves in a horizontal or oblique downward state, improve the growth angle of new leaves, inhibit the growth of new leaves, increase the leaf area, reduce the competition for nutrients with fruits, and be beneficial to the production of fruits with correct fruit shapes and improve the sugar content and storability. 3。 Rub the branches. In those years, those with vigorous growth and a slightly longer vertical angle were softened by rubbing branches except thinning, so as to enhance the moderate light of branches, improve the photosynthetic efficiency of leaves, contain trees and adjust the growth relationship. 4。 Pull the branches. 1 the vertical angle and space utilization of annual fruiting branches and flower branches adopt the technology of pulling without cutting, which can alleviate the tree potential, solve the lighting problem and promote the good development of fruits and flower buds. 5。 Ring cutting. In view of the vertical angle of the main branches, vigorous growth and inability to open angles, ring cutting technology was adopted from May to July to control the growth of trees and new shoots and promote the growth of fruits.
Cultivation of pear trees
(1) Main cultivated varieties: The pears suitable for Loudi cultivation are mostly Japanese pears (Xingshui pears) in Shari pear system and newly bred hybrid pears (Xiangnan, Huanghua, Changshilang, New Century, Cuifu pears, etc.) in the south. Among them, Xiangnan pear and Huanghua pear performed very well, with large fruit, fine meat, no residue and sweet taste. They planted it for three years and put it into production. After five years, the fruit per plant can reach more than 20 kilograms. Compared with citrus, they are not afraid of freezing injury.
(2) Planting time and method: Pear trees should be planted after defoliation in autumn and before germination in spring, and autumn is the best. Before planting, level the pear orchard according to the transplanting density, dig ditches or pits, apply base fertilizer and cover it with cooked soil. The planting depth is consistent with the original nursery. The planting density is 33-44 plants per mu in flat land, 56-67 plants per mu in mountainous area and 80- 1 10 plants per mu for dwarf rootstocks.
(3) Allocation of pollination trees: The matching of pollination trees and pears is the key measure for multi-fruit. Pollination trees should be consistent with the flowering period of main varieties. The distribution proportion is determined according to their economic value and pollen quantity. If their economic value is equal, they can be distributed according to 1: 1. Suitable configuration varieties are shown in the following table. For the existing pear orchards without pollinated trees, pollinated varieties can be supplemented by multi-head high grafting.
(4) Water and fertilizer management: pear trees like fertilizer, and apply fertilizer four times a year. Base fertilizer accounts for 50% ~ 60% of the total fertilizer in the whole year, mainly slow-acting organic fertilizer, which is applied in mid-February, and fertilization before flowering depends on the tree situation. Strong fruit fertilizer is applied in combination with available nitrogen, phosphorus and potassium fertilizer 65 ~ 75 days after flowering; Effective nitrogen fertilizer is the main fertilizer for fruit picking. In order to promote the high and stable yield of pear trees, it is necessary to apply fertilizer outside the roots, especially to protect flowers and fruits. Pear trees are weak in drought tolerance, and the southern pear areas are often dry and short of water in July and August, which requires timely irrigation; There is more rain from April to June, so drainage should be done well. Young trees (1 ~ 7 years) should be intercropped with vegetables, beans and edible fungi, which can inhibit the growth of weeds and increase the content of soil organic matter.
(5) Shaping and pruning: pear trees are mostly shaped by vacuuming and layering. The control tree is about 4 meters high, the trunk is 50-60 cm high, and the central trunk has three main branches on the first floor, two on the second floor and three or four floors 1. The main branch spacing is 60 ~ 80 cm. The pruning principle of fruit trees should be determined according to the fruit characteristics of varieties. For varieties with short fruit branches, the production branches and medium-long fruit branches should be cut short 1/3 ~ 1/2, and the short fruit branches should be sparse and strong, dense and sparse, and sparse and dense. Pruning in summer can replace thinning and short cutting with sprouting and coring.
(6) Other management: The main diseases of pear trees are rust, scab and brown spot, and the pests are pear stem bees, aphids, weevils and fruit eaters, which can be controlled by corresponding pesticides respectively. "Peeling pears in winter" refers to the combination of clearing the garden, disinfecting with Bordeaux solution after scraping, whitewashing the trunk and trunk branches, and scraping off the rough skin and old cracked skin of the trunk and trunk branches in winter. Artificial pollination, hormone spraying, flower thinning and fruit thinning at flowering stage can improve the fruit setting rate and yield of pear trees.
Prevention and control of diseases and insect pests in pear tree growth period
The climate in July and August is characterized by high temperature, high humidity, much rain and little sunshine. All kinds of fruit tree diseases are prevalent, and fruit trees are easy to grow in vain; It is not conducive to flower bud differentiation. At this time, the plow tree is in the second vigorous fruit growth period. The main task of pear tree plant protection in this period is to protect the fruit from pests and diseases. During this period, the main pests and diseases that need to be controlled in Pear Village are as follows:
1, pear scab: In July, pear scab began to infect fruits. Pale yellow spots appeared in the early stage of fruit infection, and the spots were slightly sunken after expansion, resulting in black mold. Later, the spot was stopped by a cork and cracked. Its control measures: at the initial stage of pear scab damage, spraying bordeaux mixture of 1: 2: 200; 70% thiophanate-methyl wettable powder 800-1000; 50% carbendazim WP 800 times solution.
2. Pear moth: The first and second generation larvae mainly harm the treetops, and the third generation mainly harms the pears. The fruit feeding hole of the pear fruit borer is small and difficult to find, but the fruit dropping hole is large and obvious. Its prevention and control measures: start spraying in the middle and late July, and decide the next spraying date according to the drug residue period. Commonly used drugs are: 20% pyrethroid emulsion 2000-2500 times; 50% acetaminophen emulsion 1000 times solution; 2.5% deltamethrin emulsion 3000 times solution.
3. Pear weevil: July is still the fruiting season of pear weevil, and a large number of fruits fall to the ground. The control measures are: picking the damaged fruit of pear elephant manually.
4. Hawthorn Tetranychus viennensis: In July, Hawthorn Tetranychus viennensis propagated, which did serious harm to trees and the leaves began to fall in the inner room. Preventive measures: spraying lime-sulfur mixture with 0. 1-0.3 Baume; 5% nisolone EC 1500-2000 times; 20% mite egg fat wettable powder 800- 1000 times; Pay attention to the protection and utilization of natural enemies; Pay attention to timely watering in dry season to compensate for the water loss of trees caused by drought and mite hazards.
5. Pear pink aphid: In late June, nymph climbed to the calyx depression of pear fruit to do harm, and a large number of fruit insects appeared in early July; Prevention and control measures: the spraying period is in early July, and the chemicals used are: 40% isocarbophos 2000 times solution; 40% omethoate emulsion 1500 times solution; The mixture of 80% dichlorvos EC and 50% methamidophos EC is 1000 times.
6. Peach moth: The adult appears at the end of July, bears fruit at the beginning of August, and bears fruit at the end of August. The control measures are as follows: when the rate of eggs and fruits reaches 0.5%- 1%, spraying drugs is started; The chemicals used are: 20% mirex emulsion 3000-4000 times (which can also control harmful mites); 25% diflubenzuron No.3 colloidal suspension 1000 times solution; 50% cartap EC 1000 times solution; 20% pyrethroid emulsion 2000-4000 times solution. In the process of chemical control, attention should be paid to the alternate use of chemical agents for each pest or disease to prevent drug resistance.