A Detailed Guide to Magnolia denudata Propagation Methods, Pest and Disease Control, and Afforestation Techniques
Magnolia denudata is the white-flowered variety among magnolias, with beautiful blooms and high ornamental value, and has always been deeply loved by people. Below, the editor of Huinong Network will explain the propagation, pest and disease control, and afforestation techniques of Magnolia denudata.
1 Biological Characteristics and Value of Magnolia denudata
1.1 Morphological Characteristics
Magnolia denudata has an egg-shaped crown, alternate leaves, leaf tips that are short and abruptly pointed, wedge-shaped leaf bases, and large obovate leaves with a glossy surface. Young branches and buds are covered with short down, and in winter the branches and buds are tight, with pale grayish-green long hairs on the outside of the buds. The whole plant blooms before leafing out, with pure white, fragrant flowers; the petals and sepals are similar, and the flowering period is 8-10 d. It blooms in March to April and the fruit ripens in September to October. The fruit is a black aggregate follicle, and the seeds are heart-shaped. When site conditions are good, the tree height can reach more than 15 m.
1.2 Ecological Habits
For planting Magnolia denudata, it is advisable to choose slightly acidic soil on hilly land below 200 m elevation, on sunny slopes, with deep soil layers; when the soil is poor, growth is poor and the growth rate is relatively slow.
1.3 Economic Value
Magnolia denudata flowers have a certain medicinal value. They contain volatile oil, mainly citral, clove oil acid, etc., and also contain alkaloids, capric acid, rutin, oleic acid, vitamin A, etc. They can be used for headache, nasal congestion, acute and chronic sinusitis, etc., and also have an inhibitory effect on common dermatophytes; because the petals are thick and fleshy and have a unique delicate fragrance, they can be eaten fresh or dried.
2 Seedling Raising
Magnolia denudata is commonly propagated by sowing, grafting, layering, root division, and other methods; cutting propagation has a low survival rate. Magnolia denudata is conventionally raised from seed. In vegetation restoration of ecological public welfare forests, it is crucial to use seedlings propagated from superior provenances for afforestation.
2.1 Seed Collection and Storage
2.1.1 Seed Collection
For seed collection, the mother trees should preferably be middle-aged and vigorous trees over 20 years old with straight and full trunk form, healthy growth, no pests or diseases, and abundant fruiting. Seeds can be collected when the fruit skin of Magnolia denudata hardens, turns red, and begins to split slightly to reveal the red aril, collecting fully mature seeds. In the Anqing area, seed collection begins in late August and ends before September 20. Collecting too early, when the seeds are not yet mature, will affect the germination rate; collecting too late, when the aggregate follicles have fully split, will cause the seeds to fall off on their own and make them difficult to collect, and they are also easily gnawed by rats.
2.1.2 Seed Processing
(1) Threshing. After the fruits are collected, they should be spread out in the sun to dry. When the fruit skin splits on its own, the seeds can be released, yielding red seeds. During drying, the seeds must not be exposed to moisture; once dampened, the seeds will no longer split, so they must be protected from rain and dew.
(2) Soaking seeds. Soak the already released seeds in water. At this time, plump seeds will sink to the bottom, while empty shriveled seeds and impurities will float on the surface; remove the empty shriveled seeds and other debris. The soaking time is generally 1-2 d and must not exceed 2 d, and the seeds should be stirred frequently during this period. During soaking, 3%-5% sodium hydroxide can be added to help accelerate the softening of the aril and make cleaning easier.
(3) Cleaning. Repeatedly rub and wash with plant ash to prevent mold during storage. If there are obvious white spots at the seed hilum, it means the seeds have not been cleaned thoroughly and will easily become moldy later, so they need to be cleaned again.
(4) Drying in the shade. After cleaning, place the seeds in a ventilated place and spread them thinly to dry in the shade. The faster the shade-drying process, the better. In humid weather, an electric fan can be used to blow the seed surface dry, while turning them by hand once every half hour. The seeds must not be placed directly in direct sunlight, otherwise they will lose viability. Normal seeds range in color from dark yellow to black; seeds that are light yellow and white should be picked out. After 20 d of shade drying, the seeds will basically be dry.
2.1.3 Storage
Magnolia denudata seeds are mostly stored in low-temperature moist sand. Ordinary river sand is washed clean and disinfected with 0.2% potassium permanganate. The moisture level should be such that it forms a ball when squeezed and breaks apart when rubbed. Storage method: layer sand and seeds in piles indoors, with each sand layer 2-3 cm thick.
2.2 Nursery Site Selection and Treatment
Sowing seedbed preparation. Magnolia denudata has fleshy roots and fears waterlogging, so the nursery site should be selected on sandy loam with relatively high terrain and good drainage and irrigation conditions. Before sowing, carry out three ploughings and three harrowings, and apply sufficient base fertilizer (application rate: decomposed cake fertilizer or compound fertilizer 3,000 kg/hm2), disinfect the soil with Tuzet or carbendazim, and make raised beds with level surfaces. Cover the bed surface with yellow subsoil about 10 cm thick.
2.3 Sowing and Management
Sow in late March to early April. Sow seeds by drilling in rows, with a sowing rate of 60 kg/hm2. After sowing, cover with 0.2 cm thick sawdust or burned ash soil, spray thoroughly with water, and cover with rice straw or build a shade net to keep the bed surface moist.
2.4 Pest and Disease Control
During the seedling stage, focus on controlling seedling damping-off and root rot. In June to July, the plum rain season brings much rain and excessive humidity, making disease outbreaks likely. Promptly pull out and burn diseased plants. When disease occurs, spray 300-600 times Bordeaux mixture or 65% zineb 600 times solution, or drench with 70% thiophanate-methyl wettable powder 1,000 times solution.
3 Afforestation
3.1 Site Selection
For Magnolia denudata, it is advisable to choose sunny slopes in the middle and lower parts of slopes with medium or relatively deep soil layers, preferably loose acidic or slightly acidic soil in valleys and at the foot of mountains, and avoid lowlands with standing water and flat land with poor drainage.
3.2 Afforestation Site Preparation
Use hole-shaped site preparation, with a specification of 40 cm x 40 cm x 40 cm. Tree roots, stones, weeds, etc. should be removed from the holes. During site preparation, keep topsoil and subsoil separate; when backfilling, backfill topsoil first, then subsoil. Backfilling can be done together with fertilization.
3.3 Afforestation Density
The afforestation density of ecological public welfare forests should refer to the crown width of the species and use appropriately dense planting. In local ecological vegetation restoration afforestation, the afforestation density of Magnolia denudata is selected as 3 m x 4 m.
3.4 Establishment of Mixed Forests
In selecting small compartments for vegetation restoration afforestation, use two or more native tree species for mixed afforestation. Locally, Magnolia denudata and sweetgum are selected for block mixing. Plant Magnolia denudata on deep soil and sweetgum on shallow soil.
3.5 Afforestation Time
The best afforestation time for Magnolia denudata is before bud break, or before leaf expansion at the end of flowering. Water the seedlings thoroughly once 4-5 d before lifting, so the plants absorb sufficient water, which helps survival after planting and helps the soil form a ball when the seedlings are lifted. When digging, injure the root system as little as possible, and when lifting the seedlings, they should be kept with a soil ball; the diameter of the soil ball should be 8-10 times the ground diameter of the seedling. Tie the soil ball well with straw rope to prevent it from breaking apart during transport.
3.6 Technical Requirements for Afforestation
In afforestation techniques, do the following: plant immediately after lifting, shorten the time as much as possible, and keep the roots moist; carry out necessary root and branch pruning before planting; for planting large seedlings, keep soil balls, dig large holes, apply heavy base fertilizer, and set up supports promptly after planting; appropriate deep planting can suppress sprouting and benefit growth; water immediately after planting.
4 Tending and Management
4.1 Weeding and Soil Loosening
To promote the growth of young forests, before canopy closure after afforestation, green shrubs can be interplanted. Combined with water and fertilizer management for the green seedlings, loosen the soil and weed the young forest from May to August to promote its growth.
4.2 Water and Fertilizer Management
Magnolia denudata likes fertilizer. In addition to applying base fertilizer at planting, appropriate fertilization should be carried out every year afterward. Fertilization is carried out 4 times each year, namely: apply a nitrogen, phosphorus, and potassium compound fertilizer once before flowering to improve flower quality and benefit spring growth; apply a nitrogen fertilizer once after flowering to increase plant growth and expand the nutritional area; apply a phosphorus and potassium compound fertilizer once in July to August to promote flower bud differentiation and increase the degree of lignification of new branches; apply a fully decomposed fermented barnyard manure once before winter, which can increase soil activity and ground temperature.
4.3 Shaping and Pruning
Magnolia denudata has strong sprouting and reproductive capacity, and multiple-trunk stems often form from sprouts, affecting the formation and growth of the main trunk. To control the growth of sprouting stems, within 1-2 years before and after canopy closure of the young forest, split out the sprouts in the forest, organize the trunk form, and maintain the growth of the main trunk.
4.4 Pest and Disease Control
Magnolia denudata is a tree species with relatively strong disease resistance. The main problem is longhorn beetle damage, with occasional damage from underground pests such as white grubs. Green Weilei 500 times solution can be used to kill longhorn beetles, and 50% phoxim emulsion 1,000 times solution can be used to drench the roots to kill white grubs.
The above is the editor's summary from Huinong Network on Magnolia denudata propagation, pest and disease control, and afforestation techniques. Have you all learned it? The planting benefits of Magnolia denudata are considerable, so friends who want to grow it should not miss out.
Pest and Disease Control of Potted Magnolia denudata
Magnolia denudata, scientific name (Michelia alba DC.), is the white-flowered variety among magnolias. Also known as magnolia and yulan. It is a deciduous tree of the Magnoliaceae family, generally 2-5 m tall or up to 15 m tall. The flowers are white, large, and fragrant, opening before the leaves, with a flowering period of about 10 days. It is a famous Chinese ornamental plant, an important spring-flowering tree in the north, the city flower of Shanghai, with a cultivation history of about 2,500 years, and a precious ornamental tree for gardens. It is native to central China and is now cultivated in Beijing and south of the Yellow River basin. In ancient times it was often planted in front of pavilions, terraces, buildings, and towers. Nowadays it is mostly seen as solitary plantings and scattered plantings in gardens and factories and mines, or as street trees on both sides of roads. In the north it is also grown as potted stump bonsai. It has now been introduced and cultivated all over the world. Pest and Disease Control of Potted Magnolia denudata1. Leaf removal and pinching. After each batch of flowers finishes blooming, remove a small number of old leaves to promote new branch growth and flower bud formation. During the plant's growth period, pinch frequently to control apical dominance and promote more lateral branches.
2. Supplementary nutrients. This is one part of flowering-period management. In October, apply an organic liquid fertilizer mainly of phosphorus and potassium once every 5-7 days, such as decomposed cake fertilizer water. Fertilization should be light and frequent, or use the method of applying dilute first and then concentrated. Never apply raw fertilizer, otherwise it will burn the roots. At the same time, spray the leaves with 0.3% monopotassium phosphate every 7-10 days.
3. Watering. Magnolia denudata has fleshy roots, so it both needs water and fears waterlogging. From early summer to late autumn, water once a day to keep the soil moist. When watering with tap water, prevent soil alkalization. If leaf yellowing is found, water the roots with 0.7%-0.8% vinegar solution, or spray the leaves with 0.3%-0.4% vinegar solution; the effect is relatively good. In rainy seasons, water must not accumulate in the pot, otherwise the roots will rot.
4. Light. Magnolia denudata needs sufficient sunlight, and during the growth period it should be maintained in a sunny place with long sunshine and strong light, especially during the flowering period; daily light must not be less than 6 hours. If kept in a shady place, it will only grow leaves and not bloom, or bloom very little, with thin and long branches, pale leaves, thin blades, and no luster, which is unfavorable for growth.
5. Pest and disease control. In addition to controlling yellowing disease and root rot, anthracnose should also be controlled. If disease is found, promptly remove diseased plants and diseased leaves, and at the same time spray the leaves with 50% carbendazim 500-800 times solution, or use 70% thiophanate 800-**** times solution for control. If aphids are found damaging tender buds and flower buds, spray with laundry detergent 500 times solution to kill them, then rinse the branches and leaves with clean water. Scale insects can be controlled by spraying 0.3%-0.4% vinegar solution.
Control and Application of Common Pests and Diseases of Magnolia denudata