Cultivation techniques of Rhododendron

Azalea is one of the ten famous flowers, known as "beauty in flowers". It has many species, abundant flowers and leaves, beautiful and colorful, mainly distributed in southwest provinces, divided into four categories: hairy cuckoo, eastern cuckoo, summer cuckoo and western cuckoo, among which western cuckoo is the most beautiful flower in cultivated types. In recent years, with the rise of the flower industry, rhododendron has also been more common cultivation in the northern region, and its cultivation techniques are described as follows:

1. Propagation technology: cutting propagation and shoot propagation.

Cuttage propagation is the most widely used propagation method in rhododendron cultivation. Generally, strong semi-lignified new branches are cut in May and June, about 5-8 cm long, the lower leaves are cut off, and 2-3 top leaves are reserved for cuttings. The base of cuttings is best dipped in solutions such as indolebutyric acid or ABT rooting powder, and then cuttings are placed in loose and breathable acidic soil rich in humus. The temperature is maintained at 20-25℃. Shade and regular spray moisture are used to promote the germination of new roots. For rare varieties that are difficult to survive, such as Western Cuckoo, cut off about 3-4 cm of young shoots as scions, cut the base into wedges with sharp knives, use Mao Cuckoo as rootstock, use young shoots to split, and then put them under shade with plastic film binding, and cover the scions and rootstocks with plastic bags to keep them moist.

Second, fertilizer and water management: Rhododendron growth and development requires acidic soil (soil pH value of 5.5-6.5 is appropriate). Because the northern soil is alkaline, the basin soil needs to be mixed with decomposed pine coniferous soil and other humus soil. Rhododendron root system for the thin beard-like roots, the fertilizer concentration and water quality requirements strictly, fertilizer should follow the principle of timely and appropriate, thin fertilizer frequently. Before flowering in spring, phosphorus fertilizer can be applied once a month to promote the growth of branches and buds. After anthesis, nitrogen and phosphorus fertilizer were applied for 1-2 times. 9-10 Apply phosphate fertilizer 1-2 times during budding period. In the growth period, flowering period fertilizer and water requirements more, winter dormancy, slow growth in summer to control fertilizer and water, in case of rotten roots. Azaleas like moist and cool environment, dry climate in the north, should be watered and sprayed in time to maintain a high air humidity. Watering water to alum fertilizer water and rain water is good, such as common water to add a small amount of ferrous sulfate and vinegar. Watermelon or tomato can also be cut into small pieces and applied to improve soil quality and flower quality.

Third, plastic pruning: in order to accelerate the blooming of plants, azaleas often promote new branches by picking, and for flowers clustered and affecting flower shape, buds can be thinned early, which not only makes the flowers big and fresh, but also facilitates the growth and flowering of plants in the coming year. Rhododendron germination is strong, branches seriously affect plant growth and development, reduce its ornamental and commercial, so it needs to be adjusted by pruning. Pruning is generally carried out after flowering in spring and autumn, cutting off dead branches, oblique branches, excessive branches, pests and some cross branches to avoid nutrient consumption and make the whole plant bloom plump.

Fourth, flowering control: Rhododendron flower bud differentiation in autumn, through cold storage and heating treatment, can be artificially controlled flowering. To make rhododendron blossom ahead of time, it can be moved to greenhouse culture, temperature control at 20-25℃, and often spray water on branches and leaves, maintain more than 80% relative humidity, so that after a month and a half can bloom. To delay the flowering of rhododendrons, the rhododendrons that form buds can be kept at a low temperature, maintained at 2-4℃, watered when the pots are dry, removed outdoors in summer and autumn, and can bloom after 2 weeks.

V. Pest control: Common diseases of Rhododendron include leaf swelling disease, leaf spot disease and brown spot disease. The control methods are as follows:

1. Leaf swelling disease. Before the disease occurs, especially when the shoots and leaves are pulled out, the Bordeaux mixture of 1:1:200 can be sprayed, and the diseased leaves can be removed in time; before germination, the Bordeaux mixture of 0.3-0.5 Baume degree or 1:1:200 can be sprayed for 2-3 times, usually once every 7-10 days; after the disease occurs, 65-80% mancozeb 500 times solution or 0.3-0.5 Baume degree stone sulfur mixture can be sprayed for 3-4 times, once every 7-10 days.

2. Leaf spot disease and brown spot disease. Spraying 70% thiophanate-methyl 1000 times solution, 20% triadimefon 4000 times solution and 50% mancozeb 500 times solution once every 10 days for 7-8 times in May and August can effectively control the development of disease. Ferrous sulfate can also be added to prevent leaf yellowing.

3. Coin disease: the top of the injured shoot leaves are covered with dense white or pink mite layers, sometimes the leaves produce mite gall, which is mostly caused by aphids stabbing the leaves. Its control method: while clearing the diseased leaves, spraying chemicals containing copper sulfate, spraying omethoate emulsifiable solution or putting furadan directly into the basin and other methods can control aphids and other pests with biting mouthparts.