Cutting is the main breeding method, and seeds can also be used for breeding.
Select the cutting mother tree.
On the surface, it is difficult to distinguish the male and female weeping willows, but it is easy to distinguish them from the flowers. In order to select purer male scions, it is necessary to identify the female parent trees to be selected at flowering stage. There are three ways to identify flowers: one is to identify flowers directly from their appearance. Generally, female catkins are slender, up to 5 cm long and drooping; The male inflorescence is thick and short, and the length is generally 2 ~ 4 cm. The second is to identify from flowering and fruiting. Male plants only blossom but not bear fruit. The third is to distinguish from the anatomical structure of flowers. Female flowers have stigma and male flowers have stamens. After the male and female plants are identified, the male plants are fixed and marked as mother plants for cutting.
Cultivate rhizome
In order to quickly cultivate large-scale weeping willow male seedlings, we chose fast-growing willow variety J 172 as rootstock. In the winter of the first year of cutting, select the robust willow branches, the thickness of which is generally above 0.5cm, cut them into 18 ~ 20 cm cuttings, bundle 50 branches, put them in a cool and dry place, and store them in clean and moist river sand. During storage, ensure that each cutting is in full contact with wet sand to keep moisture. In the spring of the following year, after the soil was thawed, 667m2 of 3m3 decomposed organic base fertilizer was applied, and then the soil was prepared for the border. Generally, the width of the border is 1.5m, and the length depends on the nursery. The cutting density is 0.5×0.2m. The cutting depth should be equal to the cutting top and ground. It can be inserted directly or obliquely. After the cuttings are inserted, both sides of the cuttings are solid with feet and watered. Timely loosen soil, weed, replenish water and prevent insects. In that year, the height of cuttings can reach more than 1.5m, and the root diameter can reach 2cm. After the seedlings grow to 1 year, they need to be divided into rows and plants, and the density of the seedbed should be adjusted to1× 0.4m. After grading, the seedlings should be planted, and the density is also1× 0.4m. After another year of cultivation, the height of the seedlings can reach more than 2.5m, and the root diameter can reach 4cm, so that they can be fixed.
Collection and storage of scions
In the winter of the first year of grafting, select the robust branches of the year from the pre-marked male and female trees and store them with clean wet river sand. The storage method is the same as the rootstock cutting storage method. Bud grafting, split grafting, skin grafting and double tongue grafting are commonly used.
Grafting time
Using different grafting methods, the grafting time is different. T-bud grafting is generally adopted, and the grafting time is selected at the end of August and the beginning of September. When T-bud grafting is adopted, scions should be picked as needed. Cut off the leaves together with the petioles and moisturize them with moisturizing materials. When split grafting, skin grafting and double tongue grafting are adopted, the juice should start to flow in spring, and the rootstock should be grafted when it begins to sprout, usually in Rizhao, Shandong Province at the end of March and the beginning of April.
Grafting and grafting site
Weeping willow seedlings generally have requirements for dry height, and the high part should be selected for grafting. After two years' cultivation, the height of J 172 willow seedlings can generally reach more than 2.5m, and the grafting site can be 2 m. Single head (bud) or multi-head (bud) grafting can be used in production. When the seedling is 2m high, it is thinner, or when there are no branches, it can be grafted with single head (bud), and when the seedling is 2m high, it can be grafted with multiple heads (bud).
Post-grafting management
Film should be released at any time after the grafting survives, and bud grafting can be put in 1 month. Splitting, skin grafting and double tongue transplantation generally take 40 days to terminate. After the film is released, all the buds on the rootstock are wiped off at any time, and grafting, skin grafting and double tongue grafting are carried out to facilitate the germination of grafted buds. You don't need to smear buds in the same year after uncovering the film. Before the willow sprouts in winter or the following spring, all the rootstock branches above the bud and below the bud are cut off to ensure the germination of the bud. Weeping willows grow rapidly after grafting, so it is necessary to pick new buds in time. Generally, when the new shoot grows to 50cm long, it begins to pick the core and head, select the bud with the right growth direction, keep it full and strong, and cut off its upper branches. Single-head (bud) grafting generally requires more than two enucleations to form a complete crown with evenly distributed branches. Should be timely loosening, weeding, fertilization and watering. 50kg of ammonia water was applied before germination, and urea was topdressing again at the end of May and the beginning of June, and the amount of fertilizer applied was 25kg. Topdressing NPK compound fertilizer 15kg every 667m2 in the middle and late July. Generally, ditch strip application or hole digging point application is adopted, after fertilization, the soil is firmly covered, and then watering is carried out. Stop topdressing after the middle and late August. The fast-growing willow variety J 172 was selected as the rootstock for grafting seedling of weeping willow. After four years of cultivation, the seedlings can leave the nursery, with straight stems and few pests and diseases. After afforestation, the seedlings only bloom but do not bear fruit, which fundamentally solves the problem of flying floc pollution and has a very broad market prospect.
Weeping willow is one of the commonly used street trees. To make weeping willows grow fast and straight, we should pay attention to the following points:
Fecal fluid
Plant growth needs a lot of water and fertilizer, so applying more fertilizer and watering in Qin Yingduo can generally grow to about 2 meters a year.
decrease
Weeping willows are difficult to control in the growth process and often bend very long. Pruning is the key to make weeping willows grow straight.
1. Pruning of cuttings: The lateral buds of cuttings should be removed when cutting.
2. Pruning of annual seedlings: If the annual seedlings are less than 1 m or in bad shape, they should be cut into about 10 cm in the early spring of the following year, leaving only one main branch and all other side branches cut off.
When the annual seedling grows to 2 ~ 3 meters, the lateral branches can't be cut off completely, otherwise the tree will bend easily. You can remove diseased branches or short-cut side branches to balance nutrient supply, so that although there are many side branches, the tree grows straight.
3. Pruning of two-year-old seedlings: Two-year-old seedlings can cut off the lower branches and the upper branches.
Pinch by hand
Because the trunk of weeping willows is soft, you can pinch it hard at the corner. Over time, the tree will grow straight.
Through the above management measures, weeping willows can grow into street trees with a thickness of 3 cm and a height of 3 m after three years.
control of insect
The main pests that harm weeping willows are Liujinhua insect and aphid. Both of them are leaf-eating pests. The sulfur mixture can be sprayed 3 ~ 5 times in early March, and 25% diflubenzuron No.3 can be sprayed 2000 times in early April. In midsummer, a small number of pests can be seen, such as willow beetles, ladybugs, inchworms, thrips curvata and so on. Methamidophos or 40% omethoate 0. 1% solution can be sprayed alternately for prevention and control, once a month.
The main diseases are canker and canker. The prevention and control measures are mainly to strengthen management, strengthen tree potential and improve their own disease resistance. When the disease is mild, cut 0.5cm vertically and horizontally on the diseased branches to reach the xylem scar, and then spray the following bactericide 15% aqueous caustic soda solution 21:10 ~1:kloc-0/2 soda water 200 times solution 4, without removing it. For plants with serious diseases, it is necessary to pull them out in time and isolate them from non-disease plants to prevent proliferation. The replaced diseased plants should be burned in time to effectively control the spread of germs.