Management of young litchi trees
On the basis of improving the survival rate, increase the number of roots, expand the growth range of roots and increase the green leaf layer, cultivate strong and evenly distributed backbone branches and expand the crown, laying a good foundation for early fruit and high yield.
1, fertilization is based on the principle of diligent application and thin application. Soil fertilization begins one month after planting, and within two or three years, it mainly focuses on increasing root quantity and promoting shoots and strengthening shoots. It is appropriate to master "one branch with two fertilizers" or "one branch with three fertilizers", that is, to apply nitrogen-based quick-acting fertilizer when the top buds of branches germinate to promote the normal growth of new shoots. When the elongation of new shoots basically stops and the color of leaves changes from red to light green, the second fertilizer is applied to promote the rapid greening of new shoots, improve photosynthetic efficiency, and make branches stout and leaves thick. When the new shoots turn green, applying fertilizer for the third time will accelerate the senescence of the new shoots, shorten the shoot-sprouting period, and be beneficial to the multiple germination of the new shoots. The amount of fertilizer applied depends on soil properties and the size of young trees. After planting, these trees have few small roots. Apply about 25-30g of compound fertilizer, 20-25g of urea, 0/5-20g of potassium chloride/kloc and 50-75g of calcium superphosphate to each plant alone or in combination, and reduce the dosage when mixing. From the second year, the amount of fertilizer applied will increase correspondingly, which is about 40-60% higher than that of the previous year. In addition, according to the growth of trees, foliar fertilizer can be sprayed at the rapid growth stage of branches. Commonly used fertilizers are urea 0.3%-0.5%, potassium dihydrogen phosphate 0.3%-0.5%, magnesium sulfate 0.3%-0.5%, borax 0.02%-0.05% and boric acid 0.05%-0. 1. 2. The young roots of irrigation and drainage litchi are few and shallow, which is greatly influenced by the high moisture of topsoil. One-year-old litchi young trees often have the phenomenon of "withering back", especially for the ring-branch seedlings with new branches sprouting once or twice after planting, the water management is relaxed. Therefore, attention should be paid to watering and moisturizing in dry days, and water should be prevented from accumulating in tree trays in rainy days.
3. loosen the soil and improve the soil. Litchi mycorrhiza is aerobic, and soil loosening and ventilation can promote root development. Young orchards are planted in combination with intercropping, weeding six or seven times a year. Starting from the second year, litchi fruit in hilly and mountainous areas should be deeply turned over, combined with the application of organic fertilizer to expand holes and improve the soil. In litchi orchard with high water level, attention should be paid to cultivating exotic soil and thickening soil layer.
4. Intercropping and ground cover. Young and young litchi orchards should make full use of space for interplanting and interplanting. Soil mulching can reduce soil temperature in summer, keep warm in winter, prevent drought and keep moisture, reduce weed growth and increase soil organic matter. Mulching method can plant green manure and grass, cover the soil surface after harvesting in dry season, or bury it in rhizosphere soil layer. Dead things are generally covered with weeds and crop stalks in the field to cover the tree tray and cultivate thin soil on it.
5. Pruning young litchi trees. 3-4 main branches should be cultivated in shaping and pruning, so that their incident angles are appropriate and evenly distributed. The principle of pruning is that it should be light rather than heavy, mainly cutting off cross branches, too dense branches, bent branches, weak branches and ears that are not allowed to bear fruit, so that nutrients can be effectively used and the crown of the tree can be expanded. Branches that can be cut or not are kept temporarily. The pruning period is carried out before the new branches sprout. Plastic trimming can be carried out by trimming, coring, pulling, hanging and spreading.
6, cold protection and tree protection. When the temperature drops below -2℃ in winter, it will be damaged by freezing, especially when young trees sprout more times and stop growing late. Before the cold comes, the branches and leaves are not fully mature and their cold resistance is low. The last branch can be fully aged as soon as possible to prevent the winter shoot from sprouting after 1 1; The top of the young tree crown is covered with straw to prevent frost; Litchi orchard accumulates turf leaves, according to the forecast, smoke and prevent frost before frost comes; Cover the soil surface where the roots grow with green manure, crop branches and leaves or garbage, and then cover it with thin mud.
Management of litchi fruit trees
1, scientific fertilization. According to the research on mineral nutrition of litchi in recent years, the plant with annual growth of 15-20 years produces fresh fruit 100 kg, and the annual fertilization amount is: N 1.6- 1.9 kg, P2O5 1.2-2.0 kg. Fertilization throughout the year is mainly divided into three periods.
① Pre-flowering fertilizer: applied at the end of June165438+ at the beginning of February. The function is to promote flower bud differentiation, flower ear development, improve flower quality, increase fruit setting rate and delay spring senescence. During this period, nitrogen, phosphorus and potassium accounted for about 20%-25% of the annual application, and phosphorus accounted for 25%-30%.
② Fruit-strengthening fertilizer: applied about 10- 15 days after flowering. Its function is to supplement the consumption during flowering, ensure the nutrients needed for fruit growth and development, reduce the secondary physiological fruit drop, promote fruit growth, avoid excessive consumption of nutrients in trees, and lay a good foundation for autumn shoot germination. This time, potassium fertilizer is the main fertilizer, combining nitrogen and phosphorus, and potassium fertilizer accounts for about 40%-50% of the annual fertilization.
③ Fertilization before and after fruit picking: It should be applied about 7- 10 days before fruit picking, which can accelerate the recovery of tree vigor after fruit picking, promote the development of autumn shoots, cultivate strong fruiting branches, and lay a foundation for high yield in the next year. This period is dominated by nitrogen fertilizer, combined with phosphorus and potassium. The amount of nitrogen application accounts for about 45%-55% of the annual fertilization, and phosphorus and potassium account for 30%-40%. Pay attention to the use of organic fertilizer, and apply it after fruit picking in autumn and in late spring. Litchi is mainly fertilized by soil, supplemented by foliar spraying according to the actual needs of each phenological period. Such as using 0.3%-0.4% urea, 0.3%-0.4% potassium dihydrogen phosphate, 0.03%-0.05% compound nucleotide, 0.05%-0. 1% boric acid, 0.02%-0.05% borax and 0.3%-0.5%.
2, intertillage and scarification
① intertillage weeding: intertillage weeding 2-3 times a year. Combined fertilization before or after the first fruit picking can promote new shoots and accelerate the recovery of tree potential, and the shallow turning should be about 10- 15cm. The second time is done after the autumn shoots mature, and the depth can be 15-20cm. Cutting off some water-absorbing roots reduces the water-absorbing ability of root groups, which is helpful to inhibit the germination of winter shoots. The third time is about a month before flowering, which should be shallow, about 10cm deep. It can loosen soil layer and promote root growth and absorption.
(2) Soil reclamation: combining autumn and winter to clear the garden. Cultivate soil on the soil surface under the canopy, with a thickness of about 6- 10cm. Don't pile it too thick, so as not to damage the roots by water and oxygen in the rooting soil layer.
(3) Deep ploughing and soil improvement: Dig ditches with a depth of 0-70cm in the soil layer around the crown, and press weeds, green manure and garbage in layers to improve the physical and chemical properties of the soil and promote the growth of root groups.
3. Irrigation and drainage. In principle, water management should master the following points according to the key phenological period: the soil should be dry in the early stage of flower bud differentiation, and water should be properly supplied in the later stage to facilitate flower bud differentiation and development; The flowering period should be less rainy and sunny, and irrigation should be done after a long drought; Water supply should be ensured during fruit development, and orchard water should be excluded during maturity; In case of drought during the germination period of autumn shoots, irrigation should be adopted to promote and strengthen seedlings.
4. Cultivate robust fruiting mother branches. Good fruiting mother branch is one of the key links to achieve high and stable yield. Requirements for good fruiting mother branches:
① Roughness: Early-maturing varieties, such as March Red, White Ash and White Poplar, and middle and late-maturing varieties with mature autumn shoots thicker than 0.45cm, such as glutinous rice and Xinfeng Black Leaf, are better than 0.4cm, with delicate branches and bad flowers and fruits.
② Length: It varies with varieties, beats and tree vigor. Early-maturing varieties or varieties with sparse and long branches, such as March Red and Fraxinus ash, the first branch 15-20cm, and the total length of the second branch is 25-35cm. For the middle and late-maturing varieties such as Xinfeng Black Leaf and glutinous rice paste, the primary branch 12- 18cm and the total length of the secondary branch is 20-25cm. The old and weak branches are slightly shorter, the young and middle branches are slightly longer, and the length exceeds a certain range, and the amount of fruit hanging decreases with the increase of length.
(3) Autumn shoot leaves: they grow normally, are abundant, mature and full, and the leaf-fruit ratio is generally 4-4.5: 1.
(4) Winter shoots will not germinate after autumn shoots mature. In order to meet the above requirements, it is necessary to promote the timely germination of autumn shoots on the basis of strengthening cultivation management, and the specific shoot release time depends on the region, varieties and tree potential.
5. control winter buds. Winter buds that promote flower bud differentiation generally do not bloom or bear unreliable fruits. The germination of winter buds is related to tree potential, maturity of base branches and climatic conditions, and its growth state is also complicated, so it should be treated separately according to its growth state and climatic conditions. If the germination period is early, the temperature is high, or the branches are strong, the southern region can promote aging by strengthening fertilizer and water management, otherwise it should be controlled.
① Drug control of winter buds: commonly used drugs are 40% ethephon 0.08-0. 16% and 98%B9-.
(2) Deep loosening and fine root cutting: For trees with vigorous tree vigor, full buds and easy to sprout winter buds, deeply cultivate the soil layer for 20-30 cm, cut off some horizontal roots, reduce the water absorption capacity, improve the juice concentration, and be beneficial to flower bud differentiation.
(3) Ring cutting: generally, it is carried out from "beginning of winter" to "Winter Solstice", and a sharp knife is used to make ring or spiral cutting on the cortex of the main branch, reaching the xylem. Trees with lush foliage and bright green leaves can be cut twice, with a distance of about 10- 15 cm. Circumcision varies from tree body to tree body, and young trees with first fruit can be carried out on the trunk or trunk branch with a diameter of 6- 10 cm. Adult trees are planted on the 2nd-4th branch, and the branch diameter is about 10- 15cm. Spiral girdling is also used for young glutinous rice cake trees. The girdling bandwidth is 0.2cm, and the girdling is 1.5-2 turns, which has a certain effect on controlling shoots, promoting flowers and keeping fruits, but it should be used with caution.
④ Stranding: It was popularized in Guangdong in recent years165438+1mid-October to1mid-February 6. For middle and late-maturing varieties that may sprout winter buds, the branches with a diameter of about 3 cm are tied with 16 wire, and twisted with 16 wire, and the bark is slightly sunken, 65438+.
⑤ Short-cut winter bamboo shoots: For the winter bamboo shoots that have been extracted, the bud length is less than 8 cm, and the degree depends on the germination time. Winter shoots should be pumped early and deep, and the base should be pumped late 1.5-2 cm, which is beneficial to the differentiation of lateral buds at the base of residual shoots into flower branches.
6. Strengthen pollination and improve fruit setting rate. The fruit setting rate of litchi varies greatly, which is generally 2%- 12% of that of female flowers. A 19-year-old Sophora japonica branch with about 90,000 female flowers. If the fruit setting rate is 2%, its yield is only 36 kg. If the fruit setting rate is increased to 12%, the yield can reach more than 200 kg, showing great production potential.
① Bee release at flowering stage: bee pollination plays an important role in improving fruit setting rate, and the number of bees released is directly proportional to the size of litchi population. Adult litchi trees can release 1-2 bees per mu of orchard, which can meet the pollination requirements. Stop spraying insecticidal pesticides during bee release to avoid bee poisoning and honey pollution.
(2) Artificial pollination: collecting pollen with a wet towel, dragging it on the blooming male flowers, putting the towel stained with pollen into clear water to wash the pollen, and then spraying it on the blooming female flowers; The method of removing powder board is to use an iron sheet with several holes, with a diameter of 4.5-5 mm, and install it at the door of the hive and in the small box below. When bees enter the hive and pass through the round hole, the pollen balls on their feet are scraped off. Packed every morning, the flowering period is 2-3 hours, and each box can take 10-30 grams of powder; Manual picking method is to manually cut off the mature spikelets of male flowers and store them for later use. The storage method can be put into a sealed container filled with desiccants such as silica gel and quicklime, or put into a paper bag and put into a fruit grid of a household refrigerator, and it can still be used after being stored at 5- 12℃ for 50 days. The temperature of artificial pollination is 20-25℃. 5 grams of boric acid can be added to every 50 kilograms of pollen liquid.
(3) Shake the flowers in time after a rainy day: When it is rainy in full bloom, shake off the water drops with hand-cranked flower branches to speed up the air drying and loose powder of the flowers, or prevent the flowers from retting.
(4) When the female flowers are exposed to high temperature and dryness, it is advisable to irrigate and spray water to improve the air humidity and promote pollination and fertilization.
7, protect the fruit. Litchi fruit dropped seriously during its development. On the basis of strengthening comprehensive measures such as fertilizer and water management and pest control, other methods are supplemented to protect fruits.
① drug fruit protection: spraying GA20-50mg/L, 2,4-D5mg/L, 5- 10mg/L NAA 20-40 days after flowering.
② Ring cutting to protect fruit: It is better to ring cut young trees to protect fruit. Generally, it is not suitable for old trees and weak trees to be circumcised about 40 days after the female flowers open and bear fruit.
8. Trim. Pruning of fruit trees can be divided into autumn pruning and winter pruning. Autumn pruning should be carried out within one month after fruit picking or before the second germination of two autumn shoots. In late winter and early spring, winter pruning is completed before new branches sprout or heading. The pruning of adult fruit trees should be heavier to concentrate nutrients, ensure the growth of branches and improve the fruit setting rate; Old trees depend on trees. Pruning should be heavy when the branches are weak, so as to promote the germination of strong new buds, and pruning should be light when the branches are weak. The key work should also be put on the rejuvenation and regeneration of root groups. Usually, branches that are too dense, shady, weak, overlapping, drooping, seriously ill, falling flowers and fruits, and dead branches are cut off. The pruning method is short cutting and dewatering, and the pruning should start from the big branches inside the crown and proceed to the periphery of the crown. After cutting, the branches are evenly distributed, and there are "money eyes" under the crown.
9. Harvest. Litchi fruit turns from dark green to yellow-green, and local red is the beginning of ripening. When ripe, the peel is all bright red. Once it turns dark red, it is overripe. It takes 7- 10 days from coloring to full maturity. In order to ensure the quality of goods and obtain a long shelf life, it should be harvested when the peel is 80% to full red, that is, the fruit is just ripe. Dark skin color is a sign of fruit aging, so it is not suitable for long-distance transportation and only suitable for short-term sales. The correct harvesting method requires taking into account the double benefits of mother tree production and commodity quality in the coming year, adopting the "short branch harvesting time" method, that is, breaking the fruit branch at the top of the branch at the base of litchi ear, commonly known as "gourd festival", leaving thick branches. Because the branches have more nutrition accumulation, the sprouted new shoots grow fast and strong, which is beneficial to cultivate excellent fruiting mother branches.
Disease control of litchi tree
Diseases on litchi trees are important factors that endanger tree growth and affect yield, and must be paid attention to. Frost blight is the most serious disease of litchi.
1. Phytophthora litchi is a fungal disease, which mainly harms fruits, flowers and young leaves. The waterlogging in the affected area is brown, and there is a white mold-like pathogen, which causes the fruit to rot and fall off, and the flowers and fruits rot or dry up. It rained continuously for several days, and the humidity was high, and the temperature was 22-25℃. Orchards with poor ventilation and light transmission soon became ill, especially after the fruits were colored.
Prevention and treatment
① Prune and clear the garden after picking the fruit to reduce the initial infection source.
(2) Spraying control, generally using 90% ethyl phosphate, 500 times of manganese zinc or 600 times of 25% erysipelas, 400 times of 58% erysipelas, 600 times of 64% antiviral alum and 2000 1000 times of chlorpyrifos. Spray before and after flowering, especially after the fruit is colored and rained, spray 3-4 times.
③ Rational fertilization, avoiding partial application of nitrogen fertilizer and increasing application of phosphorus and potassium fertilizer.
2. Anthracnose is a fungal disease. When the fruit is diseased, the lesion is round and brown, with brown edges and orange sticky particles in the center. The damaged pulp becomes stale and rotten, and the tree is weak, which can form dead branches or brown branches and leaves. The first dip was mainly the diseased branches and leaves on the tree. 24-28℃ is the most suitable for its onset.
Prevention and treatment
(1) Clear the garden in winter to reduce the source of disease.
② Spray 800 times carbofuran wettable powder, or 1000 times carbofuran 2000 wettable powder, or 1000 times 50% thiophanate methyl wettable powder, or 400 times mirex.
Disease and pest control of litchi trees
Pests on fruit trees are also an important factor that harms tree growth and affects yield. Litchi stinkbug, fruit borer, litchi gall mite, inchworm, Cerambycidae, scale insects, thrips and litchi leaf gall midge are the most common.
1, litchi stinkbug scale. One generation occurs every year and overwinters as sexually immature adults. They mate in February-April, and lay the most eggs in March-May. After several hours of initial incubation, nymphae scattered to feed, endangering twigs, ears and fruits, resulting in dead branches, falling flowers and fruits.
Prevention and treatment
(1) Spraying 600 times of 90% trichlorfon or 20% Anlubao 1000 times of solution before the overwintering adults start to lay eggs or during the initial incubation period of eggs;
② stinkbug scale of litchi was released for biological control at the early stage of spawning.
2. Lychee stem borer (also known as LEPIDOPTERA). Guangdong and Guangxi have 10- 1 1 generation a year. Overwintering as larvae in the winter tips of litchi and longan or at the top of the ear axis of early-maturing litchi flowers. Overwintering adults appear at the end of March and the beginning of April, and their eggs are scattered in the cracks of the fruit or on the ears and shoots. After hatching, the larvae feed on the fruit or tender shoot from the bottom of the eggshell, resulting in fruit drop, insect dung fruit, dry ear or tender shoot, and the mature larvae cocoon and pupate on the closed leaves.
Prevention and treatment
(1) inhibit winter buds, do a good job of clearing gardens and reduce insect sources;
(2) When the pupa emergence rate reaches 40% and 80%, spray the mixture of 90% trichlorfon 800 times 88 17 times or 20% Anlubao 1000 times.
3. Litchi small gray butterfly. There are three generations a year, and the first generation larvae damage early-maturing fruits from April to May. Generally, it is drilled into the fruit from the middle of the fruit to eat pulp, stone and shell. The circular periphery of the hole is neat and smooth, and there is no insect dung attached to the hole, which may cause fruit drop. One larva can harm 2- 12 fruits. It can be controlled by spraying 88 17-500 times or 20% metronidazole 8000 times.
4. Apriona germari. Once a year or twice a year, overwinter under the trunk or bark with young larvae or pupae. Adults appear from June to September, and their backs are covered with black and tiger skin patches, which look like turtle shell patches. Eggs are mostly laid under the cortex of branches or forks, and the thickness is 1-3cm. After hatching, the larvae feed under the bark and gradually penetrate into the xylem to form a long cavity. Adults like to eat around the cortex of branches, resulting in dry branches.
Prevention and treatment
(1) kill the adult artificially, and frequently check the branches from August to June in 65438+February, and find that there are half-moon spawning points in the cortex, that is, scrape off the eggs with a knife or hatch the animals for the first time;
(2) Dip a cotton ball in dimethoate or dichlorvos emulsion 5- 10 times and stuff it into the cavity;
③ fumigation with "Keniuling" capsule is effective in killing larvae.
5, litchi gall mites. Every year, 10 generation occurs, and adults and nymphs overwinter on leaves or branches. It began to breed in large quantities in April, and it was the most harmful in May-June. Nymphs and adult mites suck the juice of litchi leaves, shoots, ears and fruits, and the affected parts form yellow to brown felt.
Prevention and treatment
(1) Clear the garden, cut off the burnt leaves and reduce the source of insects;
② Spray 20% dicofol 800- 1000 times solution, or 40% dimethoate 1000 times solution, or spray propargite and chlorpyrifos.
6. Lychee leaf gall midge. The leaves were badly damaged. Young larvae overwinter in litchi old leaf gall. In February and March, mature larvae leave the galls and pupate in the soil. In the first half of April, adults fly out of the soil and lay eggs on young leaves. After hatching, larvae dive directly into mesophyll from the back of young leaves. The affected part gradually expanded into a bubble-like cavity.
Prevention and treatment
① Before the overwintering adults emerged in the first half of April, 40 times of fine sediment mixed with 5% zinc and sulfur was sprinkled in the whole garden, and then the topsoil was shallowly cultivated;
② Spraying 40% omethoate 1000 times solution or 90% trichlorfon 800 times solution on leaves in spring and autumn.
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