Key Points of Pruning and Planting Management Techniques for Chinese Mahogany (Toona sinensis)
China is the place of origin of Toona sinensis. Since ancient times, rural areas in China have had the traditional habit of planting Toona sinensis around houses and at the edges of fields. Because Toona sinensis gathers the essence of a whole year, with its nutrition concentrated in the small tender buds, its quality and color are very satisfying. The buds of Toona sinensis not only contain relatively high amounts of nutrients such as protein, fat and vitamins, but are also rich in trace elements such as calcium, phosphorus, iron, potassium and magnesium. It is a woody vegetable with bright color, delicious taste and high nutritional value. However, due to the extensive management methods of long-term scattered planting of Toona sinensis trees, the yield and quality of Toona sinensis have been seriously affected.
Pruning of Toona sinensis Trees When Planting Toona sinensis
1. Spring pruning
Spring pruning of Toona sinensis is shaping pruning, generally carried out at the same time as the harvest of the buds. Starting from the 2nd year after planting Toona sinensis, remove the terminal buds of the 2-year-old treetops, and 2 to 3 new buds will sprout that same year. If the trunk height is suitable, the new buds can be retained, and after lignification they will become 2 to 3 side branches; if the trunk height is too high, the new buds can be pinched (the buds must not all be picked off) to encourage the lower bud scales to sprout new buds, and 2 to 3 sprouted new buds can be retained at the desired positions, becoming side branches after lignification. After the 3rd year, new buds will again grow at the tips of the 3 side branches. During pruning, remove the terminal buds of the 3 side branches, and that same year each side branch will again sprout 2 to 3 new side buds, forming new side branches after lignification. After being shaped in this way, each tree will have 6 to 9 main branches. This kind of tree shape has a tall trunk, large branches, a thick canopy layer, good ventilation and lighting, a large harvest surface and relatively stable yield.
2. Summer pruning
Because the yield and quality of Toona sinensis mainly depend on the number of terminal buds, and high yield can only be achieved when there are many branches and many terminal buds per unit area, necessary summer shaping and pruning of Toona sinensis trees is required to promote the formation of more branches. Summer pruning is generally carried out around 15:00 on sunny days in July to August, which is beneficial for wound healing. Never prune on cloudy days. On Toona sinensis trees that have already been shaped by pruning, top or shorten branches that grow too vigorously or too tall, so as to promote the sprouting of side buds to form new branches and rejuvenate the weaker parts, forming more short side branches with plump terminal buds.
3. Winter pruning
Winter pruning is best carried out in early winter (or late autumn) and in the early spring dormancy period. Thin out 1-year-old overly dense branches, overly weak branches, pest- and disease-damaged branches, dead branches and perennial old branches. The pruning knife or axe must be sharp. When pruning, cut close to the trunk from bottom to top, and the cut should be smooth and the wound small. Never tear or pull the bark, as this affects tree growth and development.
4. Rejuvenation
After 7 to 8 years of harvesting, when the sprouting sites have moved outward to the outer layer of the canopy, growth has weakened, and new buds are few and thin, it indicates that the tree head has already aged and should be renewed by head replacement. Head replacement is generally carried out in spring when harvesting buds. Method: cut branches from the 3rd-year branches and leave stubs, that is, cut off all branch heads produced after the 3rd year. Note that the stub length of the 3rd-year branches should be 20 to 30 cm, which helps promote new branches, maintain the integrity of the tree shape and keep the tree vigorous. In the same year after head replacement, new buds should grow on each stubbed trunk, but excessive pruning will cause poor tree growth. If the stubs are insufficient, new buds often grow on the main branches in the 2nd year, spoiling the tree shape. In some rejuvenation cases only the main trunk remains, which causes multiple branches to regrow, and excessive pruning can also cause the tree to die.
Management of Toona sinensis Trees When Planting Toona sinensis
1. Heat preservation
Toona sinensis likes warmth and is suitable for cultivation in areas with an annual average temperature of 8 to 10°C. Newly planted young plants will freeze and die at -10°C, while mature large trees can overwinter safely at -20°C. Therefore, in cold northern regions, newly planted young plants should have their trunks protected and kept warm in winter to prevent frost injury.
2. Fertilizer and water
Toona sinensis is a fast-growing tree species in the early stage and has strong adaptability to soil, but deep soil layers, rich calcium content and fertile sandy loam are best. Toona sinensis absorbs the most nitrogen, followed by potassium, and the least phosphorus. Every autumn and winter, ring trenches can be opened to apply an appropriate amount of thoroughly decomposed high-quality farmyard manure, plant ash, diammonium phosphate, etc. Toona sinensis likes moisture and is not drought-tolerant. During drought, it should be watered appropriately to keep the soil moist and promote growth and development. Too much water easily causes excessive vegetative growth, and the root crown is prone to rot, so attention should be paid to drainage in rainy seasons.
3. Harvesting buds
The growth period of Toona sinensis buds is short, so they should be eaten early, fresh and tender. There is a saying: “Before the rain, the Toona sinensis buds are as tender as silk; after the rain, the Toona sinensis buds are like wood.” The harvest standard is preferably purple-red bud color and bud length of 10 to 15 cm. When harvesting, the terminal buds should be picked first, then the side buds. If the terminal buds are not harvested, the lower side buds are difficult to grow or grow poorly. When harvesting buds, they should be gently picked off by hand at the base of the leaf stalk. When harvesting from branches after the tree has been shaped, 1 strong side bud must be retained on each main branch and must not be picked. On old trees renewed by head replacement, 1 strong side bud must also be retained on each branch. Tall trees should be climbed to harvest, so as to avoid excessive damage to the main branches; places that cannot be reached by hand can be harvested with a long hook, and thin branches and weak branches with no retention value should be broken off together with the branch. Toona sinensis buds can be harvested 2 to 3 times each year. After harvesting, tie them into small bundles of 100 to 200 g, put them in plastic bags and seal them to prevent water loss and wilting.
4. Removing root suckers
Toona sinensis has a shallow root system and strong suckering ability, and many sucker shoots often emerge from the root crown, which both affects the growth of the main trunk and consumes nutrients. Therefore, as long as the main trunk is growing well and no new Toona sinensis seedlings need to be propagated, all root suckers should be removed promptly and completely to ensure vigorous growth of the tree.
5. Pest and disease control
Toona sinensis has relatively few pests and diseases, and leaf rust and powdery mildew are likely to occur in summer and autumn. Leaf rust mainly damages leaves. In summer, irregular yellow-brown lesions appear on the leaf surface, and in winter irregular black lesions appear on the leaf underside. Diseased plants grow slowly, and in severe cases early defoliation is caused. The disease is caused by infection by Toona sinensis flower rust fungus and Toona sinensis multilayered rust fungus transmitted through airflow. Powdery mildew also mainly damages leaves. The surface of diseased leaves fades green and becomes mottled yellow-white, white powdery patches appear on the leaf underside, and later granular small round spots form and turn dark brown. The disease is caused by infection by spores of the Toona sinensis ball-needle shell fungus transmitted by airflow. These 2 diseases can be controlled by spraying 500 times dilutions of triadimefon solution.
The main pests of Toona sinensis include Toona sinensis caterpillars, nettle moths, cloud-patterned longhorn beetles, etc. During the larval stage, 800 times dilutions of trichlorfon solution can be sprayed to kill them; during the adult stage, 1500 times 40% dimethoate emulsifiable concentrate can be used for control. Longhorn beetle larvae can also be killed by manually injecting trichlorfon solution into the insect holes. If tea yellow mites are found causing damage, spray 15% pyridaben emulsifiable concentrate at 1500 to 2000 times dilution for control.
What Is Toona sinensis
Toona sinensis, also known as Xiangzhuangtou, Dahongchunshu, Chuntian, etc., is also called Chunmiao in the Anhui region. Its root has two layers of bark, so it is also called Chunbaipi. It originated in China and is distributed across a wide area north and south of the Yangtze River. It belongs to the Meliaceae family. It is a deciduous tree, dioecious, with even-pinnately compound leaves, panicles, white bisexual flowers, and oval capsule fruits with winged seeds. The seeds can be used for propagation. The tree is tall, and besides providing Toona sinensis buds for food, it is also a preferred tree species for landscaping. In ancient times, Toona sinensis was called Chun, and Ailanthus altissima was called Chu.
Chinese people began eating Toona sinensis long ago, and it has now become a habit. As early as the Han Dynasty, Toona sinensis was already accepted by people across the country. It is also worth mentioning that Toona sinensis buds are very nutritious and can have certain dietary therapeutic effects, with good effects on conditions such as externally contracted wind-cold, rheumatic arthralgia, dysentery and stomach pain.
Efficacy and Effects of Toona sinensis
1. Appetizing and strengthening the spleen
Toona sinensis is a famous seasonal delicacy and contains volatile aromatic organic compounds such as toosendanin, which can strengthen the spleen, appetize and increase appetite.
2. Anti-aging and beauty
It contains vitamin E and sex hormone substances and has anti-aging effects and the effect of tonifying yang and nourishing yin, so it has the reputation of “pregnancy-promoting hormone” and also has a very good effect in lubricating the skin, making it a good food for health care and beauty.
3. Clearing heat and promoting diuresis
Toona sinensis can clear heat and promote diuresis, and it also has the effect of promoting urination and detoxifying, and can play a certain auxiliary role in conditions such as enteritis, dysentery and urinary system infections. Therefore, there is also a folk saying: “Eating Toona sinensis buds often keeps illness away.”
4. Expelling parasites and treating ringworm
Toona sinensis has antibacterial, anti-inflammatory and insecticidal effects, and can be used to treat ascariasis, sore ringworm, scabies and other diseases.
5. Astringing blood, stopping dysentery and stopping metrorrhagia
Toona sinensis can play a certain role in drying dampness and clearing heat, and can also be used to astringe and consolidate, with very good effects on chronic diarrhea, chronic dysentery and intestinal hemorrhoids with bloody stool. In addition, it can also be used to treat abnormal uterine bleeding and leukorrhea.
When the editor was young, Toona sinensis was seen relatively often. With the various requisitions and development in rural areas now, Toona sinensis is seen less and less. The editor remembers often eating scrambled eggs with Toona sinensis as a child. It smelled of a special fragrance, and eating Toona sinensis is also very helpful to human health.