A Complete Analysis of the Cultivation Techniques for Osmanthus Seedlings
Osmanthus has luxuriant foliage and is evergreen, with a long lifespan; it blooms in autumn and fills the air with fragrance. It is an ornamental flowering plant and aromatic tree native to China. The areas where osmanthus is concentrated and cultivated in China are mainly the vast tropical and northern subtropical regions north of Lingnan up to the Qinling Mountains and south of the Huaihe River. Osmanthus trees are quite favored in home cultivation. Below, the editor of Qiannong Network will introduce the cultivation techniques for osmanthus seedlings!
Selection of the Cultivation Environment for Osmanthus Seedlings
Osmanthus trees prefer a warm and humid climate, tolerate high temperatures but are not very cold-hardy, and are a subtropical tree species. Osmanthus is not very demanding regarding soil; apart from alkaline soil and low-lying land or soil that is too clayey and poorly drained, it can generally grow, but deep, loose, fertile, well-drained slightly acidic sandy loam is more suitable.
Osmanthus is suitable for growing in deep, well-drained, fertile, humus-rich, slightly acidic sandy loam. It is not tolerant of drought and barrenness; on shallow, compacted, poor soil, it grows extremely slowly, with sparse branches and leaves, small thin leaves, yellowed leaf color, no flowering or very little flowering, and even periodic dieback of the top, and in severe cases the entire osmanthus plant dies.
Osmanthus likes sunlight but has a certain ability to tolerate shade. Young trees need some shading; after maturity, relatively sufficient light is required to ensure normal growth of the osmanthus. According to observation, when one side of a single osmanthus tree's crown is close to a wall, or when the crowns of two osmanthus trees overlap each other, the side close to the wall or the overlapping part of the crown quickly becomes sparse, affecting the shape and beauty of the entire crown. It can be seen that osmanthus is suitable for planting in ventilated and well-lit places; osmanthus likes a clean and ventilated environment and is not tolerant of smoke and dust damage, and after being damaged it often fails to bloom; it fears waterlogging and standing water. If harmed by waterlogging, the root system turns black and rots, the leaves first have scorched tips, then the whole leaf turns yellow and falls off, and eventually the entire plant dies.
Breeding Techniques for Osmanthus Seedlings
Osmanthus propagation and seedling methods include cuttings, layering, grafting and sowing, etc., with cutting propagation being the main method.
1. Cuttings: The cutting time is generally June-July or September-October, and sandy loam is suitable for the cutting bed. For the cuttings, use semi-mature branches of the current year, with terminal branches being the best. After cutting, shade in time, water thoroughly, and strengthen water and fertilizer management. Generally, healing begins 20 days after cutting, and rooting occurs in 30-40 days. In winter, cold protection measures are needed, and in the following year the seedlings can grow to about 30 cm tall.
2. Layering: Layering is divided into air layering (high layering) and ground layering, and can be done in all four seasons. The air layering method is carried out in early April, and the ground layering method is best carried out in early April or the plum rain season. When layering, wounding or ring-barking must be done, and after 1 year it is separated from the mother plant. For ground layering, the buried depth of the layer is about 4-5 cm, and the more bent the buried branch portion, the better.
3. Grafting: The grafting propagation time is March-April. The rootstock is mostly small-leaf privet (Ligustrum sinense) or large-leaf privet (Ligustrum lucidum). The grafting method is branch grafting; cleft grafting, split grafting and approach grafting are all acceptable. During grafting, shading is required and attention should be paid to moisture retention. Cleft grafting and split grafting require the graft union to be as low as possible, generally cutting off the rootstock at 3 cm above the ground. After tying, mound soil up to the top of the scion so that it may root from the scion part, improving the survival rate.
4. Sowing: Sow in winter or early spring, in drills, with a row spacing of 15-20 cm, sowing 30-40 seeds per meter of row, with a sowing rate of 8-10 kg per mu, covering with humus soil or burned soil about 1.5 cm thick, and covering with grass. Generally, germination begins 40-50 days after sowing and can last up to 50-60 days, with very uneven germination. July-September is the period of vigorous seedling growth, so attention should be paid to topdressing and drought resistance. One-year-old seedlings can leave the nursery when they are over 30 cm tall.
5. Seedlings leaving the nursery: After layered seedlings and grafted seedlings have rooted, they can be planted in winter or planted in the nursery to cultivate large seedlings. When cutting seedlings reach over 30 cm, sowing seedlings reach over 25 cm, and the ground diameter reaches over 0.4 cm, they can leave the nursery for afforestation or be transplanted to the large-seedling cultivation area. When lifting seedlings, the root system should be kept as intact as possible, and after lifting they should be planted in time; if long-distance transport is needed, attention should be paid to moisture retention.
Pest and Disease Control for Osmanthus Seedlings
1. Scale insects
① Combine with manual pruning to scrape off overwintering pests.
② Before the tree sprouts, spray 5% anthracene oil emulsion or 5-degree lime sulfur mixture.
③ When scale insects first appear and have not yet formed a waxy layer, spray malathion 1000-fold solution or 25% iminophosphorus emulsifiable concentrate 1000-fold solution, and the control effect is relatively good.
2. Red spider mite: It mainly sucks nutrients from osmanthus buds, leaves and flowers, causing osmanthus buds and flowers to dry up and making branches and leaves turn yellow or wither. Spray 3-5 degrees Baume lime sulfur mixture before sprouting, or spray 0.3-0.5 degrees Baume lime sulfur mixture before and after flowering.
3. Leaf spot disease: It mainly harms leaves, and in severe cases causes leaves to fall off. In high temperature and high humidity, this disease develops very quickly. In June-July before flowering, 0.5 kg of 80% mancozeb wettable powder can be diluted with 250-300 kg of water for spraying prevention. During the growing season, according to the condition of the disease, a 1:1:100 equal-strength Bordeaux mixture can be sprayed.
4. Rot disease: It mostly occurs on the trunk, large branches and branch crotches. Control measures: strengthen fertilizer and water management, enhance tree vigor, improve drought resistance and disease resistance, and scrape and treat promptly after onset. According to the disease pattern, the focus of inspection and scraping treatment should be placed in early spring and autumn, and applying 5-degree lime sulfur mixture after scraping has a relatively good effect.