What are the disadvantages of planting walnut trees at home?

Walnut tree Walnut is also called walnut. Walnut, almond, cashew nut and hazelnut are called "four big nuts" in the international market. Walnut trees adapt to deep, loose, fertile and moist soil and cool climate and ecological environment. Walnut kernel is rich in nutrition and is a good tonic. Each catty of walnuts is equivalent to 5 catties of eggs or 9 catties of fresh milk. Walnut kernel also has high medicinal value, and has good curative effect on kidney deficiency, lumbago, lung deficiency, chronic cough, asthma, constipation, weakness after illness and neurasthenia. Walnut kernel is a high-grade edible oil with high oil content, generally 60%. Walnut is tough and elastic, fine in texture and beautiful in color. It is the first-class material used in military industry and furniture industry. The walnuts in Qinling Mountain are good. Morphological characteristics: [Family] Deciduous tree of Juglans of Juglandaceae, up to 35m high, with grayish white bark, shallow longitudinal crack, flaky pith, and villous tips of young branches; 2-year-old branches are often hairless. The pinnate compound leaves are 25-50 cm long, with 5-9 leaflets, 65,438+03 is rare, ovoid to ovoid, and the terminal leaflets are usually large, 5-65,438+05 cm long and 3-6 cm wide, with a sharp or tapering apex, a round or wedge-shaped base, sometimes heart-shaped, entire or with inconspicuous blunt teeth, and the surface. The male inflorescence is 5 5- 10/0cm long, the male flower has 6-30 stamens, and the calyx is 3-lobed. Female flowers 1-3 are clustered, and the style is 2-lobed and reddish. The fruit is spherical, about 5 cm in diameter and grayish green. When I was young, I had glandular hair, but when I was old, I lost it. The inner nut is spherical and yellowish brown with irregular grooves on the surface. The flowering period is from March to April, and the fruiting period is from August to September. Its footprints are almost all over the world, mainly in America, Europe and many parts of Asia. Its output is in addition to the United States, that is, China. Walnut has a long history of cultivation in China. In the Natural History written by Zhang Hua in the 3rd century BC, it was recorded that "when Zhang Qian went to the Western Regions, he had to return walnut seeds". Walnut's hometown is Iran in the west of Asia, and it was introduced to China when Korea and Zhang Qian went to the Western Regions. Today, walnuts are distributed all over China. For a long time, the working people in China have carefully cultivated many new varieties of high-quality walnuts by using the common and wild walnut resources in China. If classified by origin, there are Chencang walnut and Yangping walnut; According to maturity classification, there are summer walnuts and autumn walnuts; According to the smoothness of the shell, there are light walnuts and hemp walnuts; According to the thickness of the shell, there are thin-shell walnuts and thick-shell walnuts. Key points of cultivation: sow in August and September, collect seeds after the fruit is ripe, peel, dry and store. Soak the seeds in cold water for 2-3 days in mid-March, take them out, mix them with wet sand, and pile them in sunny places. Cover with wet sand with a height of 30-35cm and a thickness of 1 0cm, sprinkle water1time every day to keep moist, and cover with a straw curtain or film at night to keep moist and warm. 10- 15 days later, you can start sowing. Choose 1 time every day, sow in batches, and the sowing water is sufficient. 1. The row spacing of ditches shall be 40-50 cm, and the plant spacing shall be 15-20 cm. When sowing, the two suture lines should be parallel to the ground, and the depth should be 3-5cm from the ground. After covering the soil, the soil is compacted to keep moisture. The sowing amount is about100 kg/mu, and the seedling yield is 7000-8000 plants/mu. Grafting: Grafting is carried out from late March to early April. First, collect scions. In mid-March, when the buds are about to germinate, the 1 year-old branches with strong growth and no pests and diseases are collected as scions. After harvest, the varieties were stored in wet sand, and grafting began when walnut rootstocks germinated in early April. The thickness of the rootstock should be about 65438±0.5cm, and the grafting should be carried out at a place 10 cm above the ground. Walnut has bleeding when grafting, so it is not easy to survive. Before grafting, the rhizosphere must be cut and drained to xylem, then split or grafted, and then the wound should be tied with plastic strips, and the upper end of the scion should be painted to prevent water evaporation. After survival, you should pick the core and loosen the soil in time, and the loosening time should be carried out when the new length is more than 20cm. When the grafted seedlings grow to about 40cm, fix them with small bamboo poles or wooden sticks to prevent wind folding. Cultivation management: The planting time is before and after germination in late March, and the survival rate of 1-2-year-old seedlings is high. After planting, water and fertilizer management should be strengthened, soil loosening and weeding should be done frequently, drainage should be paid attention to in rainy season, and pest control should be paid attention to in June and July. Pruning should be carried out in the growing period, and the dry height should be kept above 3 m. Do not prune after defoliation, otherwise it will easily cause bleeding and affect the growth of trees. The main pests and diseases are anthracnose; Pests include aphids and moths. The suitable range originated in Europe and Central Asia. Xinjiang and other provinces in North China are cultivated, and there is a small amount of cultivation in Yanling. Walnut branch blight is a fungal disease. It mainly harms the branches and causes them to die. The damage rate of plants is generally around 20%, and it can reach 90% in severe cases. This disease mainly affects the growth and yield of trees. The symptom of the disease is that after the 1-2-year-old branches are damaged, they gradually dry from the top to the trunk, and the leaves turn yellow and fall off. Dense black spots are produced on the dead branches, and mucus flows out when the humidity is high, forming black tumor-like protrusions. Bacteria overwinter on diseased branches and invade through wounds, only hurting weak trees. The control method is to remove diseased branches and burn them centrally; The control time and chemicals used are the same as those used to control walnut anthracnose. Walnut for garden has majestic crown, white trunk, lush foliage and shady ground, which can be used as road greening and protection in garden.