What are the control methods for pear bonsai black spot disease

Many people nowadays like bonsai, and a great advantage of bonsai is that plants that would need to be grown in open outdoor space can now be placed indoors in bonsai for viewing. Pear bonsai is one of them, but many people growing pear bonsai say black spot disease troubles them greatly, and indeed, pear bonsai black spot disease is a common disease of pear bonsai. Based on many years of control experience, to control pear bonsai black spot disease you should mainly grasp two key links: first, eliminate overwintering pathogens; second, chemical control. Now let's study the control methods for pear bonsai black spot disease in detail with the editor of Huinong Network.

Eliminate overwintering pathogens

Eliminate overwintering pathogens with chemicals. Before bud break, spray once with 3-5 degrees Baume lime sulfur mixture, or 45% lime sulfur crystal at 50-60 times dilution, or 45% amobam aqueous solution at 100-200 times dilution, to eliminate pathogens overwintering on the tree.

After bud break and before flowering, spray to kill pathogens inside the buds, reduce the number of diseased shoots formed, and reduce sources of pathogens. Commonly used effective agents include 40% myclobutanil wettable powder at 5,000-6,000 times dilution, 62.25% mancozeb-myclobutanil wettable powder at 600 times dilution, 12.5% diniconazole wettable powder at 1,500-2,000 times dilution, 25% difenoconazole emulsifiable concentrate at 6,000-8,000 times dilution, etc.

Thoroughly remove diseased shoots. Promptly remove diseased leaves and diseased fruit.

Chemical control

An important link in controlling pear black spot disease. Spraying periods and frequencies differ among different bonsai gardens and in different years. But overall, the principle of "grasping both ends" should be implemented, namely from after petal fall to around wheat harvest, and 1.5 months before harvest. The period from after petal fall to around wheat harvest is the key period when overwintering pathogens infect young leaves and young fruit; the purpose of control is to control primary infection, that is, to control disease in young leaves and young fruit. Generally, spray about 3 times before wheat harvest, and once after wheat harvest. During the 1.5 months before harvest, the main aim is to prevent fruit damage, and generally about 3 sprays should be applied. The specific spraying time and frequency should be flexibly adjusted according to rainfall conditions.

There are many kinds of agents for controlling black spot disease. Commonly used effective agents include 40% myclobutanil wettable powder at 5,000-6,000 times dilution, 62.25% mancozeb-myclobutanil wettable powder at 600 times dilution, 12.5% diniconazole wettable powder at 1,500-2,000 times dilution, 25% difenoconazole emulsifiable concentrate at 6,000-8,000 times dilution, 6% fenarimol wettable powder at 1,000-1,500 times dilution, and 40% flusilazole emulsifiable concentrate at 8,000-10,000 times dilution. When spraying, it must be uniform and thorough, ensuring "turn the underside up and the topside down, penetrate all four sides."

The above are the control methods for pear bonsai black spot disease compiled by the editor of Huinong Network. Have you all learned them? If you want to learn more agricultural technology knowledge, please follow Huinong Academy!

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How to grow elm bonsai: care for elm bonsai

How to grow elm bonsai: care for elm bonsai

Elm trees, especially old elm stumps growing in the wild, have experienced many years of human chopping and hacking, or wind stripping and rain erosion, animal gnawing, etc., gradually forming many different strange postures. Some have gnarled roots and interlaced branches, vigorous and antique; some turn decay into wonder, with dead roots and new leaves, opening up a distinctive scene of their own, making them excellent material for making bonsai. Here we offer our humble views on the production and care management of elm bonsai, for reference only.

First, stump selection must be strict. Try to choose small and medium-sized stumps, so as to facilitate balcony cultivation; the stump material must be fresh, and those that are withered and rotten or have no fibrous roots should not be used. Newly dug old elm stumps should be planted in plain sandy soil in the ground or planted in clay pots to "nurse the stump," generally best done from late autumn to early spring (the survival rate is highest in the two or three months before bud break). Before planting, the root system and branches and trunk must first be pruned as necessary, and sticky sap often flows from the cut (sap bleeding); if too much liquid seeps out, it will seriously affect the survival rate. The biggest disadvantage of all elm species is that they easily bleed sap. If the stump material cannot effectively overcome this disadvantage before and after planting, then it is very difficult to ensure the survival of the stump. For this, you can use paint or wax to seal the cut, or apply a layer of erythromycin ointment or sulfonamide ointment, then sprinkle on fine sandy soil. After the cuts are properly treated, do not pot them immediately; place them in a cool place to air-dry for a few hours, letting the wounds naturally lose water and form a protective film, which can greatly reduce the occurrence of sap bleeding after the stump is potted. Elm trees like dryness and fear wetness. After planting, firm the soil and it is not necessary to water; simply spray the branches and trunk with clean water 1-2 times a day, and after 3-4 days water once thoroughly. Afterward, do not water unless dry, and absolutely do not allow waterlogging.

Second, when shaping elm bonsai, based on the basic form of the old stump, use techniques such as wiring and pruning to create different forms of bonsai such as straight-trunk style, curved-trunk style, slanting-trunk style, waterside style, cliff-hanging style, wind-swept style, forest style, and root-over-rock style. Shaping can be done either during the dormant period after leaf fall or during the growing season, but the bud-break period must be avoided.

After the elm bonsai has taken shape, plant it in a purple clay pot before spring growth begins, taking care to choose loose, breathable, well-drained sandy soil rich in humus. It is best to mix yellow sand : pine needle soil : loess = 4:3:3; this soil is both breathable and water-retentive, and will not become waterlogged. Normally place it in a well-ventilated spot with ample light for care, and keep the potting soil on the dry side. During high-temperature and dry summer weather, you can sprinkle water on the ground around the plant, but it is not advisable to spray water directly on the leaves, lest the leaves become larger and lose their beauty. After a new stump has survived, do not rush to fertilize; this is an important reason many people fail at nursing stump material. Fertilizing should be done after autumn, and fully decomposed dilute liquid fertilizer is best.

Elm has strong sprouting ability and grows quickly, so during the growing season it should be pruned frequently, cutting off overly long and messy branches to maintain the beauty of the tree shape. The best viewing period for elm bonsai is when new leaves have just emerged. If all the leaves are removed in early to mid-August, and fertilizer and water management is then strengthened, new leaves will grow again by late September, increasing ornamental value. In winter, move it to a cool indoor room with bright light, or bury the whole pot in soil outdoors in a wind-sheltered, sunny spot, reduce watering, and let the plant fully enter dormancy. During care, repot once every 2-3 years to keep the bonsai growing vigorously and full of vitality.

Chinese elm

The Chinese elm has a graceful tree shape, an elegant posture, mottled bark, and fine dense branches and leaves. It is very suitable for solitary planting or group planting in courtyards, or for pairing with pavilions and rockery. It can also be selected as a greening tree species for factory and mining areas. Chinese elm wood is hard and can be used for industrial timber; the stem bark fiber is tough and can be used for ropes and artificial fibers; the roots, bark, and young leaves used as medicine have the effects of reducing swelling, relieving pain, detoxifying, and treating heat; external application treats scalds and burns from water and fire; the leaves can be made into a crude pesticide to kill red spiders.

Morphological characteristics

Deciduous tree, or in winter the leaves turn yellow or red and persist until after the new leaves open the following year before falling, up to 25 m tall, DBH up to 1 m; crown broadly rounded, trunk base sometimes with buttress roots, bark gray or gray-brown, splitting into irregular scaly thin flakes that peel off, exposing red-brown inner bark, nearly smooth, slightly uneven; current-year branches densely covered with short pubescence, dark brown; winter buds ovoid, red-brown, hairless. Leaves thick in texture, lanceolate-ovate or narrowly elliptic, rarely ovate or obovate, the two sides of the midvein unequal in length and width, 1.7-8 (often 2.5-5) cm long, 0.8-3 (often 1-2) cm wide, apex acute or obtuse, base oblique, cuneate or one side rounded, leaf surface dark green, glossy, except for sparse pubescence in the sunken midvein area, elsewhere hairless, lateral veins sunken, leaf underside lighter in color, sparsely short-pubescent when young, later becoming hairless or with sparse hairs along the veins, or with tufts of hairs in the vein axils, margin from base to apex with blunt and regular simple serrations, rarely double serrations (as in leaves of sprouting branches), lateral veins 10-15 per side, fine veins obvious on both surfaces, petiole 2-6 mm long, hairy only on the upper side. Flowers open in autumn, in 3-6s clustered in leaf axils or arranged in cymose clusters, perianth upper part cup-shaped, lower part tubular, perianth segments 4, deeply cleft to the base or nearly the base of the cup-shaped perianth, pedicel very short, sparsely hairy. Samara elliptic or ovate-elliptic, 10-13 mm long, 6-8 mm wide, hairless except for the stigmatic surface at the apical notch, fruit wing slightly thick, basal stalk about 2 mm long, the wings on both sides narrower than the nutlet part, nutlet part located in the middle-upper part of the samara, upper end close to the notch, perianth segments falling or remaining, pedicel shorter than the tubular perianth, 1-3 mm long, with sparse short hairs. Flowering and fruiting period August-October.

Growth habits

Grows on plains, hills, mountain slopes, and valleys. Light-loving, drought-tolerant, able to grow on acidic, neutral, and alkaline soils, but the most suitable habitat is a warm climate with fertile, well-drained neutral soil.

Geographical distribution

Distributed in Hebei, Shandong, Jiangsu, Anhui, Zhejiang, Fujian, Taiwan, Jiangxi, Guangdong, Guangxi, Hunan, Hubei, Guizhou, Sichuan, Shaanxi, Henan and other provinces and regions. Also distributed in Japan and Korea.

Cultivation management

Bonsai production

(1) Material collection and propagation measures

Artificial propagation: Chinese elm is usually propagated by sowing. Seeds mature in October-November, the fruit wings turn yellow-brown, and they should be collected promptly, spread out to dry in the sun, winnowed to remove debris, and stored dry in bags. Sow in March of the following spring, either broadcast or in drills. For drilling, the row spacing is 25 cm; choose a windless sunny day for sowing, cover with fine soil just until the seeds are no longer visible, then cover with rice straw. They will germinate and emerge in about 30 days; uncover the straw promptly and thin the seedlings appropriately. During the growing period, manage water and fertilizer well, weed and loosen the soil, and current-year seedlings can reach 30-40 cm tall. Young saplings have thin trunks and sparse branches and relatively large leaves, so they are generally not suitable for making bonsai; it is better to cultivate them for several years, prune and shape them, and then pot them. In addition, Chinese elm can also be propagated by root cuttings to cultivate stump material, with faster results, and this is widely used in South China.

Collection from mountains and fields: Chinese elm grows in many places along watersides in the mountains and fields of Jiangnan, and is even more common in limestone mountainous areas. You can select old stumps that have sprouted after many years of cutting, especially elm stumps growing on barren slopes and poor land, by ditches, or in rock crevices in the mountains and fields; those that grow slowly, are long-lived, have been shaped by natural wind and waves, with exposed roots, thick trunks, strong and zigzagging, slanting branches and leaves, small leaves, and an old and antique posture are best. Dig them before spring bud break, cut off unnecessary roots and branches, protect the secondary roots and fibrous roots, coat them with mud slurry, and wrap them in wet moss. After digging them back, choose a ventilated, light-transmitting place with loose, moist soil for deep burial and cultivation, called "nursing the embryo." When the root system has developed and new branches and leaves are flourishing, then pot them for processing and shaping. Using old stumps as bonsai material can shorten the bonsai processing time, and the form is natural and antique, different from ordinary specimens, and easy to keep alive.

When Chinese elm wild old stumps are collected and cultivated, generally at least 2-3 years are needed before they take shape. Here is a quick-training method, especially suitable for bonsai growth. For Chinese elm stumps dug back in early spring, first plant them in clay pots for cultivation. After they survive, pay attention to removing unwanted buds at any time. Begin styling from late April to early May. When branches grow to 15-18 cm long, use fine metal wire for wiring and shaping, and pay attention to care management. When new branches sprout and grow 4-6 leaves, pruning can be carried out; generally only two leaves are kept on each small branch, then apply nitrogen fertilizer once to promote new buds on the new branches, and repeat pruning and fertilizing many times in this way so the leaves grow dense as quickly as possible. As the branches continuously thicken, the metal wire must be removed in time to prevent "wire bite." For branches not yet fixed in shape, they can be wired again to fix their form. In this way, by September a Chinese elm stump bonsai can initially take shape.

The key to this rapid shaping method is mainly to carry out wiring while the xylem of the branches has not yet hardened, so production must be done with special care, and the thickness of the metal wire must also be chosen appropriately; when wrapping, it need not be pressed too tightly, to prevent bruising the tender young branches. In addition, the work of "nursing the embryo" must also be done well, only then can the goal of potting and making bonsai one year after digging the stump be achieved.

(2) Potting process

Pot selection: Chinese elm stump bonsai generally should use glazed ceramic pots, and purple clay pots can also be used. Pot shapes are diverse and determined according to tree shape, with rectangular pots being the most common. Plain and elegant colors are best.

Soil: It has no strict requirements for soil and has strong adaptability. For potting, loose and fertile garden soil or leaf mold is suitable; good air permeability and water permeability are conducive to root development and growth and help maintain the luxuriance of the old stump's branches.

Planting: Usually plant in February-March in spring before bud break, and it can also be done in autumn. When planting, prune the roots appropriately, cut off overly long roots, and they can be raised appropriately. Chinese elm has a well-developed root system and is suitable for root-over-rock bonsai. Root-over-rock planting is relatively difficult. Generally, choose stone material with relatively deep crevices (soft stone material can be artificially carved into rock crevices), trim and arrange the tree roots, embed them into the rock crevices, and use palm fiber to tie and secure the main thick roots so they are fixed. When rooting, be careful to avoid bruising the root system as much as possible, and use green moss as padding. After rooting, smear wet river soil on the outside of the stone, then wrap it with moss, then plant the tree roots together with the attached stone into the potting soil, and carefully maintain for 3-4 years. When the root system embedded in the rock crevices has fully grown and filled the crevices, the binding can be removed. At this time the root system and the stone have formed one body, and a Chinese elm root-over-rock bonsai is basically complete.

(3) Styling techniques

Processing: Chinese elm can be shaped by pruning, and can also be processed in combination with wiring. Wiring can use palm fiber or metal wire. Because Chinese elm branches grow quickly, the wiring material should be removed in time to avoid "wire bite" and affecting appearance. For old stumps collected from mountains and fields, overly thick main trunks can be carved and shaved to reduce volume and match the side branches, while also adding antique interest. The styling of Chinese elm is best done before spring bud break or during the plum rain season.

Tree forms: Chinese elm has strong plasticity and is suitable for processing into many tree forms. Common ones include straight-trunk style, slanting-trunk style, lying-trunk style, cliff-hanging style, root-over-rock style, and combined planting style. The branches and leaves can be wired into pads or pruned into a natural-form crown. Especially when creating root-over-rock Chinese elm bonsai, when conceiving the design you can take a corner of the natural world, and a certain amount of exaggeration is allowed. To heighten the charm of a certain part, the tree can be placed above the rocks, with the tree as the main subject and the stone as secondary, without being limited by "a zhang for mountains and a chi for trees." In Chinese bonsai, the Lingnan school, Su school, and Yang school often use Chinese elm as the main tree species.

Care management

Placement location: Chinese elm should be placed in a sunny, well-ventilated spot. In summer no shading is needed; in winter it can be placed outdoors. To prevent the potting soil from drying and freezing, the whole pot can be buried in soil. Watering: Chinese elm likes moisture, and watering should be sufficient. In summer with high temperatures and strong light, water once in the morning and once in the evening, but do not let water accumulate in the pot. In autumn, watering can be reduced; in winter, if the pot is buried in soil, watering is not necessary.

Fertilizing: Apply farmyard manure or cake fertilizer once in winter as a base fertilizer. From April to October (except during the plum rain season), apply a dilute organic fertilizer once every half month to maintain the nutrients needed for normal growth. Fertilizer should mainly be nitrogen and potassium fertilizers.

Pruning: Chinese elm branches and leaves grow quickly. To maintain the bonsai shape, pruning should be done frequently. Generally, when new bud branches extend to 5-6 cm, keep only 2-3 leaves and cut off the rest. To control growth, buds and shoot tips can also be pinched off at any time.

Repotting: Do this once every 2-3 years, best before spring bud break, and it can also be done in autumn. When repotting, remove about 1B2 of the old soil, cut off some old roots, and fill with fertile, loose culture soil.

Pest control: Chinese elm has many pests, commonly including elm leaf beetle, scale insects, longhorn beetles, nettle caterpillars, and bagworms. Spray 80% dichlorvos at 1500 times dilution for control; for longhorn beetles damaging the trunk, use lime sulfur mixture to plug the insect holes.

Control of common bonsai diseases

In making bonsai from elm stumps, there are roughly two common and highly harmful diseases: root rot and witches' broom of twigs and shoots. Severe root rot directly causes the stump to die; witches' broom seriously affects the normal growth of the stump, making it difficult for branches to transition and take shape for many years, and in severe cases causes the stump body to shrink and the branches to lose form and be discarded. Root rot: The symptoms of root rot in elm stumps mainly appear during the growing period as leaves turning yellow and falling, branches gradually dying, and buds remaining dormant for a long time or stopping growth midway. When collecting wild elm stumps, great care must be taken to make the root cross-sections neat, with no wounds left, to prevent pathogen invasion. The bark layer of elm stump branches is relatively thick and contains much water, so before temporary planting to nurse the stump, the root cross-sections must be properly dried, and disinfectant solution can be applied to prevent root infection. For temporary planting, do not choose unclean soil containing humus and unfermented substances. The soil should be disinfected, and during the stump-nursing period water must be strictly controlled; never let the roots be in an overly moist and long-term soaked state, as this easily promotes the growth of root rot fungi. During repotting, if black-brown decay is found on the root bark, immediately scrape it clean with a sharp tool until fresh tissue is visible, and apply to the affected part 25% wettable powder and carbendazim at a concentration of 1000 times dilution. After the solution air-dries, pot it, and at the same time cut off and burn the necrotic roots. Also be careful not to mix the scraped residue into the potting soil, to prevent reinfection. Fertilize only after the wounds heal and new roots are produced, to enhance disease resistance. Witches' broom: Elm stump witches' broom mainly harms new shoots and leaves, showing symptoms such as clustered new shoots, upright growth, diseased branches unfolding leaves early and small, and dense branching. The witches' broom pathogen overwinters as mycelium on the damaged shoots and invades and damages when new shoots sprout the following year. In winter, when pruning elm stumps, cut off clustered shoots and burn them centrally. Before bud break in early spring, spray 5 degrees Be lime sulfur mixture, with remarkable effect. Spraying can be done once a week during the growing season, and after five rounds the witches' broom can be eradicated. During this period, in addition to avoiding rain, do not spray water on the branches and leaves either; keep the leaf surface dry.

Landscape value

The Chinese elm trunk is slightly curved, the bark is mottled and elegant, the small branches droop gracefully, and the leaves turn red in autumn. It is a good ornamental tree and a greening tree species for factories and roadside greening, often planted as a solitary landscape, suitable for planting beside ponds and near pavilions, and can also be placed among rockery, except that it has relatively many pests and diseases. It has strong sprouting ability and is a good material for making bonsai.

The tree shape is graceful, the posture elegant, the bark mottled, and the branches and leaves fine and dense, with relatively high ornamental value. In courtyards, solitary planting, group planting, or pairing with pavilions are all very suitable, and it has good ornamental effects whether used as a shade tree, street tree, or for making bonsai. Because of its strong resistance, it can also be selected as a greening tree species for factory and mining areas.

Elm

Scientific name: Ulmus pumia Linn.
Family and genus: Ulmaceae, Ulmus.
Deciduous tree, native to the north, the tree can reach several meters tall: bark color grayish, often with scales peeling off, leaves elliptic, margin serrate, dark green, leathery, and glossy. Small flowers open in March and April, fruit flat and round, with membranous wings, called elm seeds, and can be used as food.
Elm has three types: large-leaf, medium-leaf, and small-leaf. Among them, the large-leaf type is not welcomed by bonsai creators because its leaves are large and thin, and the leaf color is also inferior to the medium-leaf and small-leaf types, so it has been eliminated. The medium-leaf type grows faster than the small-leaf type, and the ornamental value of the small-leaf type is higher than that of the medium-leaf type, so both can coexist, with one chosen by those who need it.
Elm is the most ideal tree species for shaping Lingnan bonsai, and is one of the five famous trees in Lingnan bonsai (orange jasmine, Japanese bush cherry, Fujian tea, elm, and skyflower). It mainly has the following advantages.
(1) Fast growth speed (the fastest among the five famous trees). Whether in the growth speed of embryo material or in cultivation using the technique of trunk chopping and branch storage, this tree has a relatively fast speed.
(2) Small leaves, beautiful leaf shape, and lovely dark green leaf color, meeting the requirements for making bonsai.
(3) Good callus formation and great plasticity; relatively large wounds can also heal. Using this characteristic, the tree embryo stump can be transformed. If it needs to be reduced, cutting off a part can also allow natural healing; if it needs to be enlarged, the "hitting" method and "bark lifting" method can be used, using its callus proliferation tissue to become rugged nodules, which has both the beauty of vigor and can give the broad trunk part a feeling of enlargement.
(4) Branches are soft and not easily broken, which is conducive to shaping and wiring.
(5) The root crown is well developed, and using the callus principle it can be transformed at will to meet the requirements of various tree forms, and it is also ideal for shaping root-over-rock styles.
(6) High sprouting rate. Elm is one of the tree species with the highest sprouting rate; latent buds are distributed all over the body. During the growth initiation period before the Start of Spring, buds sprout on any trunk with wounds. This makes it very convenient to choose and decide the positions of bonsai branches. If a branch is needed at a certain position, make a hole there until the xylem is visible, and later buds will sprout there. After growing into a branch, the wound will naturally heal again, without leaving very obvious traces.
     2. Habits and care
Elm likes sunlight and is cold-tolerant. It needs moist soil, but also needs drainage, especially when transplanting, to prevent waterlogging and root rot.
Elm has strong sprouting ability. At the suitable season (during the Start of Spring period), buds will sprout at any wounded position. During unsuitable seasons, the whole plant must be without leaves (all leaves removed) for sprouting to achieve the ideal result. If single-branch pruning is carried out during an unsuitable season (while other branches still retain leaves), it will cause failure to sprout. Therefore, when shaping, when a certain branch has reached the required size, most often the method of early inhibition is used (binding branches and leaves to limit photosynthesis) to restrict the growth of this branch. Only when all branches of the whole plant are in proportion are they all cut together, so that all branches of the whole plant sprout together, and in this way each branch can grow in a balanced way.
When a certain branch shrinks due to disease, you can also remove all the leaves of the whole tree, which can promote the diseased branch to sprout together with all the branches, solving the disease of a single diseased branch.
Digging and transplanting elm should be done each year during the period from Minor Cold to Major Cold. Digging during this period, even if the root system of the elm suffers relatively great damage, the elm can still survive. The farther away from Major Cold, the lower the survival rate of transplanting and regeneration.
     3. Propagation methods
Elm has become a cultivated species in the south. There are two propagation methods. One is air layering (commonly called ring-barking). This method can be carried out throughout the year except during the dormant period. Air layering can produce very good shaped branches and trunks, but the stump and root system are not as beautiful as stumps propagated from root cuttings, so they are mostly used as commercial bonsai. The second propagation method is root cutting. Take from each year during the period from Minor Cold to Major Cold
the root pieces cut off when digging elm stumps (regardless of size); cut them to about 10 cm each, and plant them immediately in fully drained and breathable soil; after watering thoroughly to settle the roots (cover them in rainy weather), in about one month they will sprout and grow. With routine management, transplant and interplant the following year. For elm propagated from root cuttings, after several years the stump is sturdy and rugged, with deep cracks, and the roots are gnarled and interlaced, able to create works with distinctive artistic personality.
4. Pest and disease management
Common pests of elm include red spiders, elm oystershell scales, and cottony cushion scales. The damage symptoms of red spiders on elm are dull leaf color and dryness; under transmitted sunlight, the leaves can be seen eaten into a network pattern (the bodies are so small they cannot be seen with the naked eye). This makes the damaged tree unable to sprout and grow for a long time. The damage symptom of elm oystershell scale is that the elm branches are covered with white filamentous material; the damaged branches become thin and dry, and if untreated over time, the whole branch will wither (for control methods refer to the pest control section). Next is sunscald; under strong sunlight exposure, elm bark is easily scorched, so measures should be taken to protect the sun-exposed bark and overcome this disease.
The biggest disease of elm bonsai is branch dieback. This disease mostly occurs after the elm has become a bonsai. A perfectly good bonsai, you watch it shrink branch by branch, ruined beyond form; if it cannot be overcome in time, the loss is great.
(1) The main causes of branch dieback in elm (the same for Formosan acacia) are: elm is a tree and grows quickly in the ground, with a very developed root system. After it is transplanted into a pot (especially after becoming a bonsai in a shallow bonsai pot), the pot contains little soil, and the root system quickly fills the entire pot and becomes entangled with itself into a "root nest." This "root nest" is tight, water can hardly penetrate inside, and the water poured merely overflows at the soil surface, resulting in water deficiency and fertilizer deficiency, making the tree vigor gradually weaken. At the same time, after the work has taken shape, the branching is dense, nutrient consumption is large, and ventilation is poor, causing branches to become thin and weak, with weak disease resistance, easily inviting pests. These adverse factors are the causes of elm branch dieback. This disease first shows as delayed sprouting (normal growth should be buds maintaining a tender green sprouting state), then yellow leaves and shedding, the phenomenon of water and fertilizer deficiency. The branches inside (with poor ventilation) first age and shrink, gradually developing into disease of the whole plant. (2) The way to solve branch dieback in elm (the same for Formosan acacia) is: pay close attention to the growth state of the plant. If the above conditions are found, use a pick to probe the soil. If it is confirmed that water and fertilizer deficiency is caused by the tight "root nest," immediately take measures, using a pick to loosen the soil deep into the "root nest," so that water and fertilizer can effectively seep into the interior of the soil. At the same time, use foliar fertilization methods, and spray more on the leaf surface
with water, etc., to reduce the symptoms. When entering the dormant period, immediately repot, cut off as much of the excess root system as possible, replace with new soil, and the disease will naturally improve. Experience has shown that elm bonsai should be repotted, root-pruned, and soil-changed once every year (during the period from Minor Cold to Major Cold) to ensure normal growth.

Planting method for raw elm stumps: * Apply glue to the cut, press firmly with plain yellow mud, do not water. Place in a dark place. Water after 10 days. Shade. Mine has been planted for a full month and is growing lush branches and leaves.

Sap flow must be prevented; the cut must not contact water within one week.

      *   Cut all branches and leaves clean, trim once and for all, plant in pure sand (semi-moist), do not water for the time being, place indoors in a cool place, spray water mist on the branches and trunk several times a day, and wait until buds sprout on the branches and the pot is short of water before watering. Gradually move from indoors to a shaded outdoor place, then gradually move to normal sunlight (avoiding midday), and after about a month or more, normal management can begin depending on the situation.

Elm is distributed throughout China, and is generally transplanted during the dormant period in winter and spring, with the highest survival rate especially in February and March before bud break. Before making bonsai, first plant it in sandy soil to "nurse the stump." Before planting, prune the branches and root system. Sticky sap often flows from the wounds; if too much of this sap seeps out, it will seriously affect the survival rate. Wax, paint, etc. can be applied to the cuts, or a layer of erythromycin ointment can be applied, then fine sandy soil sprinkled on, to prevent sap outflow, but it must never be soaked in water, otherwise it will worsen the loss of sap, causing the tree roots to rot and the plant to die. After planting, firm the soil, but there is no need to water; spray clean water on the trunk 1-2 times a day, and after 2-3 days water once thoroughly. Afterward, place the plant in a ventilated, light-transmitting place for care, and water according to the principle of not watering unless dry, and watering thoroughly when watering; strictly prohibit water accumulation in the soil. The shaping of elm bonsai can be done during the growing season or during the dormant period, but the bud-break period should be avoided, so as not to lose too much sap and affect plant growth. Its form can be processed according to the basic shape of the stump into different forms of bonsai such as straight-trunk style, curved-trunk style, slanting-trunk style, dead-trunk style, waterside style, cliff-hanging style, and forest style. The crown can use either an elegant, spacious natural form, or a large round-topped tree form, and can also be processed into a regular round-pad shape. The shaping method uses both wiring and pruning: first use metal wire to wire out the basic form, then prune carefully.

Apply erythromycin or sealing wax to the wound cross-section, spray water on the page, and it is not too late to water after waiting a few more days. Otherwise, if sap bleeds, it is very hard to survive. Add plant ash to the cut roots, which can stop the sap. After planting, water once a week, add mud, then seal the soil with plastic sheeting. Leave it alone. Around March 20 next spring it will sprout. (Transplanting has caused injury, so immunity is somewhat poorer. Just put a plastic bag over the top. Remove it when the buds have 2-3 leaves, about mid-April. Do not water before that.)

How to grow sorbaria bonsai: cultivation methods for sorbaria

Sorbaria is native to northern Asia and is a shrub-type, deciduous broadleaf shrub plant. It likes sunlight and also has strong shade tolerance, is cold-tolerant, moisture-tolerant, and drought-tolerant. Sorbaria is mostly planted as a single plant in gardens and courtyards. Below is an introduction to how to grow sorbaria bonsai and a detailed explanation of sorbaria cultivation methods.

Introduction to sorbaria

Sorbaria is native to northern Asia and is distributed in China in Hebei, Gansu, Shandong, Shanxi, Inner Mongolia, Jiangsu, and other places. It is a shrub-type, deciduous broadleaf shrub plant. It likes sunlight and also has strong shade tolerance, and is cold-tolerant, moisture-tolerant, and drought-tolerant. It has no strict requirements for soil and can grow normally in ordinary soil, while growing more vigorously in moist, fertile soil. It grows quickly, has strong root-suckering ability, and is tolerant of pruning.

Spiraea is a plant of the genus Sorbaria in the Rosaceae family. It gets this name because when it blooms the flowers are dense and all snow-white. Because its leaf shape resembles willow leaves and its flowers are white as snow, it is also called "snow willow." Sorbaria is mostly planted as a single plant in gardens and courtyards. Generally, no fertilizing is necessary, but it must be watered frequently; especially in dry spring and summer periods, the soil must be kept moist.

Before winter, water sufficiently with winter water. In high-cold regions it should be protected for overwintering; other management is relatively extensive. Sorbaria has a full clump and clean, elegant branches and leaves; its value lies in producing elegant white flowers in the height of summer when flowers are scarce, and the flowering period is very long. In particular, it has killing or inhibitory effects on many harmful bacteria, so it is suitable for planting in various garden green spaces. Especially because of its shade tolerance, it is a flowering shrub species for greening the north side and shaded areas of high-rise buildings and various structures in northern cities.

1. Morphological characteristics

Sorbaria is a shrub, up to 2 m tall, with spreading branches; branchlets cylindrical, slightly flexuous, hairless or slightly short-pubescent, green when young, dark red-brown or dark yellow-brown when old; winter buds ovate, apex rounded-obtuse, hairless or slightly pubescent at the tip, purple-brown, with several alternate exposed scales.

Pinnate compound leaves, leaflets 11-17, together with petiole 13-23 cm long, 10-13 cm wide, rachis slightly short-pubescent; leaflets opposite, 2-2.5 cm apart, lanceolate to ovate-lanceolate, 5-7 cm long, 1.8-2.5 cm wide, apex acuminate, rarely caudate, base nearly rounded or broadly cuneate, rarely oblique, margin with sharp double serrations, both surfaces hairless or nearly hairless, pinnate reticulate veins, with 12-16 pairs of lateral veins, obvious below; leaflets sessile or nearly sessile; stipules leaf-like, ovate-lanceolate to triangular-lanceolate, apex acuminate to acute, margin irregularly serrate or entire, 8-13 mm long, 5-8 mm wide, slightly short-pubescent outside.

Terminal large dense panicle, branches nearly upright, 10-20 cm long, 5-12 cm in diameter, peduncle and pedicels stellate-pubescent or short-pubescent, gradually falling off in fruit stage, nearly hairless; bracts ovate-lanceolate to linear-lanceolate, 5-10 mm long, 3-5 mm wide, apex long acuminate, entire or shallowly toothed, both surfaces slightly pubescent, gradually falling off in fruit stage; pedicels 5-8 mm long; flowers 10-12 mm in diameter; calyx tube campanulate, base slightly short-pubescent outside; sepals triangular-ovate, apex obtuse or acute, sepals about equal in length to the calyx tube; petals oblong or obovate, 5-7 mm long, 3-5 mm wide, white; stamens 40-50, about 1.5-2 times longer than the petals, borne on the edge of the disc; carpels 5, hairless or slightly pubescent.

Follicles oblong, with terminal curved style, about 3 mm long, pedicel upright; sepals persistent, reflexed, rarely spreading. Flowering period July-August, fruiting period September.

2. Ecological habits

Sorbaria is cold-tolerant, tolerant of partial shade, and tolerant of pruning. It grows better in well-drained sandy loam. It grows fast, suckers easily, and is a good summer flowering plant.

Most plants in Rosaceae are sun-loving, and Spiraea is no exception. It likes sun and tolerates a certain waterlogged environment, but should not be waterlogged for long periods. It has no strict requirements for soil and tolerates a certain degree of salinity and alkalinity, and is suitable for growing in the Shanghai area.

Propagation methods of sorbaria

Sorbaria propagation is mainly by division, and it can also be sown. However, because the seeds are tiny, sowing is mostly not used. Division propagation is generally carried out before spring growth begins or after leaf fall in autumn. Dig out the suckering seedlings clustered at the base of the plant with roots, take 3-5 plants as a clump, and plant them separately.

When planting, apply 2 shovelfuls of compost in the hole as base fertilizer, and water thoroughly after planting. Afterward, water about once a week until established. Clumps more than 5 years old can grow to a very large crown width. Before early spring bud break, dig open the soil around the old clump, then cut off the surrounding root-sucker seedlings one by one from the mother plant and dig them out, move them to a nursery for cultivation, and after 1 year they can become seedlings ready for sale. For large-scale propagation of seedlings, the sowing method can be used. Store seeds dry and sow in spring the following year.

1. Division propagation

During growth, sorbaria has the characteristic of easily sprouting root suckers, and division propagation can be carried out in early spring in March and April. Select plants that grow robustly, have no pests or diseases, and have many tillers as mother plants.

The method is: dig open the soil around the roots of a mother plant more than 5 years old, cut down from the middle of the gap, separate the tillers from the mother plant, and each clump can yield 5 to 7 plants. The separated root-sucker seedlings must have complete roots. If the lateral roots of the root-sucker seedlings are thin and numerous, some should be appropriately cut off when planting. This propagation method has a high survival rate, takes shape quickly, and is relatively simple in management, but the number propagated is limited. After division, water thoroughly and move the plant to a slightly shaded place, then gradually place it in sunlight for normal care after one week.

2. Cutting propagation

This method is suitable for large-scale propagation and can be done all year round, but cuttings root fastest and have a high survival rate in March and October. For cutting soil, generally use 5 parts garden soil, 4 parts humus soil, and 1 part sandy soil, mix and make trenches to form beds, and carry out open-field cuttings. For cuttings, choose current-year or two-year mature branches from robust plants, cut them to 15-20 cm long, and retain 4-5 buds or leaves. When inserting the cuttings, insert 2/3 of the cutting into the soil, leaving only the top one or two buds or leaves above the soil surface. The cut end of the cutting should be flat, cut into a horseshoe shape, and inserted as soon as cut. Press the soil at the base of the cutting and water thoroughly once. After that, spray water 1-2 times a day and always keep the soil moist. After 20 days, reduce the frequency of spraying to prevent excessive moisture from causing branch rot. In about 1 month they can root and be transplanted.

3. Layering propagation

In March and April, bend branches on the outer part of the mother plant directly down into the soil, or girdle or notch the part pressed into the soil to promote rapid rooting. After new roots grow, separate from the mother plant and transplant in spring or autumn planting season.

Cultivation methods for sorbaria

Sorbaria has strong adaptability and does not demand much fertilizer. Apart from newly planted plants needing a small amount of base fertilizer, no further fertilizing is needed afterward, but watering is required. Generally, water thoroughly 2-3 times from leaf bud break to flowering, and water 2-3 times from the Start of Autumn to before frost, including 1 anti-freezing watering. In summer, water according to drought conditions, and no watering is needed when there is much rain. After the flowers fade, the inflorescence turns yellow and withered, affecting appearance, so the residual inflorescences should be cut off to keep the plant clean and neat and to avoid residual inflorescences competing with the plant for nutrients and water. After autumn or in early spring, diseased and pest-infested branches and old weak branches should also be cut off. For one-year-old branches, heavy pruning can be carried out to promote branch renewal and lush flowers and leaves.

(1) It has no strict requirements for soil, but grows better and blooms more luxuriantly when cultivated in deep, fertile sandy loam.

(2) It does not demand much fertilizing. When first planted, sufficient base fertilizer is needed to meet its growth requirements, and generally no additional topdressing is applied. Afterward, in combination with winter management, apply base fertilizer once every 1-2 years.

(3) Water promptly during spring drought. During summer and autumn drought, water thoroughly to keep the soil from drying out; before winter, water once with anti-freezing water.

(4) After flowering, promptly prune off remaining flower branches, diseased and pest-infested branches, and old weak branches, to keep the plant shape neat, avoid nutrient consumption, and promote robust growth and lush flowers and leaves.

How to grow sorbaria bonsai

The care of sorbaria bonsai is mainly in details such as temperature, watering, and potting soil. The maintenance of bonsai sorbaria is not as extensive as ground planting; you must always pay attention to whether the potting soil needs watering, and also prune the branches and leaves regularly. Only in this way can the advantages of sorbaria bonsai be displayed.

1. Seedling methods

1. Cuttings

Cutting propagation of sorbaria should be carried out after leaf fall in autumn. The seedbed can be chosen in a sunny, wind-sheltered place, deeply plowed and then raked fine and leveled. After the seedbed is made, fill the seedbed with 70 cm of sterilized plain sandy soil. When cutting, select robust current-year branches, each section about 12-15 cm long, spray water after insertion,

cover with plastic film to keep the substrate moist and maintain the seedbed temperature: sorbaria has strong regeneration ability, a high survival rate after cutting, and rapid growth and development. It will begin to sprout in early spring the following year, and can be potted in autumn.

2. Division

For sorbaria (Sorbaria kirilowii) plants, generally after 3 to 5 years of cultivation, they must be divided and replanted, and the time should be in September—October. When dividing, dig up the sorbaria with its soil ball, remove excess attached soil, and expose all the roots. Then, according to the gaps between the roots of the plant, use a sharp knife to cut it into several clumps, smear the cuts with sulfur powder, and properly prune away excess stems, branches and long roots. And according to the needs of greening and landscaping, carry out single-plant cultivation. After planting, water thoroughly, then water once a week thereafter, generally 3 times in a row, and the sorbaria will survive.

II. Cultivation Methods

1. Potting soil

For potting soil, it is advisable to choose loam with good permeability, strong drainage and relatively high fertility. Apply organic fertilizer once in late autumn and early winter, and apply phosphorus and potassium fertilizer once before flowering. Water moderately at ordinary times to keep the potting soil moist; it must not be too wet for a long time, and even less waterlogged. Potted plants should be placed in direct sunlight as much as possible. Low-temperature dormancy in winter is a physiological need, so they must not be placed in a greenhouse, lest it affect the next year's growth and flowering. Placing them in the open air in a wind-sheltered, sunny spot, or covering the pot with soil, is enough for them to overwinter safely. Prune every year after leaf fall until before the next year's sprouting, cutting out diseased and damaged branches, dry and withered branches, and the thin and weak among the overcrowded branches. Shorten overly long branches to keep a good plant shape, ventilation and light transmission, so as to benefit flowering.

2. Temperature and light

When cultivating sorbaria, it likes a warm, humid environment and sunlight. Adult plants can also tolerate cold and partial shade. Cuttings taken in autumn, by the next summer, are exactly in the growth period of young shoots and young leaves. Growers should, according to the position of the seedbed, pay attention to building a shed for shade to avoid direct strong sunlight, so that scattered light is sufficient. For plants that are flowering and bearing fruit, sunlight should be increased to make photosynthesis vigorous and promote vigorous plant growth.

The most suitable temperature for sorbaria growth is 18°C~32°C. If the temperature is suitable, the light is sufficient, and it is matched with reasonable water and fertilizer management, sorbaria can enter a luxuriant growth period, and on the crown, pearl-like flower buds shine brightly. Sorbaria is cold-resistant, so no cold protection measures are necessary in winter, and it can generally overwinter in the open ground.

3. Fertilization

Sorbaria does not have high fertilizer requirements. When first planted, it needs sufficient base fertilizer, which can meet its growth requirements, and generally no additional topdressing is needed. Later, in combination with winter management, applying base fertilizer once every 1~2 years is enough.

4. Pruning

After the sorbaria flowers fade, the inflorescences turn yellow and dry, affecting the appearance. Therefore, the remaining inflorescences should be cut off to make the plant clean and neat and to avoid the remaining inflorescences competing with the plant for nutrients and water. After autumn or in early spring, diseased and pest-infested branches and old and weak branches should also be cut off. Annual branches can be heavily pruned to promote branch renewal and lush flowers and leaves.

5. Watering

Water promptly during spring drought. During summer and autumn drought, water thoroughly to keep the soil from drying out. Before winter arrives, water once with antifreeze water.

Pest and disease control of sorbaria

After the plants have grown, pest and disease control work should be carried out promptly, and early control should be achieved to promote healthy plant growth. The main diseases of sorbaria include: leaf spot, powdery mildew and brown spot. The main insects to prevent and control include: scarab beetles, and citrus flatid planthoppers, etc.

1. Leaf spot

When the disease occurs, round or irregular brown spots appear on the leaves, and brown mold-like material sparsely grows on the spots on the back of the leaves.

Control method: spray a 500~800 times diluted solution of 50% thiophanate.

2. Powdery mildew

When the disease occurs, white or grayish-white flour-like material appears on the leaves. In severe cases, the young tips curl, the leaves become uneven, and they fall off early. The flowers are small and do not open, and the flower form is deformed, curled and withered.

Control methods:

(1) In late autumn, remove diseased and remnant plants to reduce sources of the pathogen;

(2) Pay attention to ventilation, reduce air humidity, strengthen light, apply more phosphorus and potassium fertilizer, and enhance resistance;

(3) After the disease occurs, promptly prune off the affected parts, or pull out diseased plants and burn them;

(4) Spray chemicals. During the dormant period, spray an equal-amount 1% Bordeaux mixture; in the early stage of the disease, spray 70% thiophanate-methyl 800 times solution or 50% amobam 800~1000 times solution.

3. Brown spot

Sorbaria brown spot mainly harms leaves. At first, brown round to irregular lesions are scattered on the leaf surface, with darker edges and an obvious boundary with healthy tissue. Later, sparse small dark brown to blackish-brown mold spots, namely the pathogen fruiting bodies, grow on the back of the leaves. The pathogen overwinters on affected leaves as mycelium or conidia. The next year it produces conidia that spread by wind and rain to neighboring plants. Generally, the disease occurs easily when tree vigor is weak or ventilation is poor.

Control methods

(1) From July—September, spray 65% zineb wettable powder 600 times solution or 70% mancozeb wettable powder 500 times solution, 25% benomyl emulsifiable concentrate 12% copper octanoate emulsifiable concentrate 600 times solution

(2) Strengthen management and improve disease resistance.

(3) In late autumn and early winter, collect diseased leaves and burn them in a concentrated way to reduce the source of the pathogen the next year.

4. Scarab beetles

Small green flower scarab beetles and others bite and eat leaves, flower buds and flowers, causing leaves to be incomplete and damaged.

Control methods:

(1) Taking advantage of the adults' death-feigning behavior, shake the branches in the early morning or evening to capture and kill them;

(2) During the adult occurrence period, spray 40% omethoate 1000 times solution, or 50% malathion 1000 times solution.

(3) Taking advantage of the adults' habit of entering the soil, scatter 2.5% phosmet powder around the plants, then loosen the surface soil after application, so that the adults contact the chemical and die of poisoning.

5. Citrus flatid planthopper

Adults and nymphs often gather in groups on the back of tender leaves to pierce and suck sap. Affected leaves, depending on leaf age, develop symptoms such as perforation, rupture, curling or thickening.

Control methods:

(1) In winter, prune out overly dense branches and dead branches and burn them to reduce insect sources;

(2) During the peak occurrence period of adults, insect nets can be used to catch and kill them;

(3) During the damage period of nymphs and adults, spray 90% trichlorfon 1000 times solution, or 40% dimethoate emulsifiable concentrate 1200 times solution for control.