Chen Yi

Heavy snow weighs on the green pines,

The pines are tall and straight.

To know that the pines are noble,

wait until the snow melts.

Cedar

Cedrusdeodara (Roxb.) G. Don, Pinaceae, genus Cedar. Cedar is the national tree of Lebanon.

Morphological characteristics: It is an evergreen tree with generally flat large branches, irregular whorls, and slightly drooping small branches. The bark is grey-brown, cracked into scales, and peels off when old. The leaves are spirally scattered on long branches and clustered on short branches. The leaves are needle-shaped, hard, with a tapered apex, and are light green to blue-green in color. Dioecious, with rare single beads, flowers solitary on top of branches. The cones are elliptical to elliptical-ovate. When mature, the scales and seeds are scattered at the same time. The seeds are winged. The flowering period is from October to November, and the male cones bloom about 10 days earlier than the female cones. The cones mature in October of the following year.

Ecological habits are native to the Himalayas and are widely distributed in countries such as Bhutan, Nepal, India and Afghanistan. The vertical distribution height is 1300-3300 meters above sea level. It prefers a warm temperate to mid-subtropical climate with annual precipitation of 600-1000 mm, and grows best in the middle and lower reaches of the Yangtze River in my country. It has strong cold resistance, and large seedlings can withstand short-term low temperatures of -25°C, but often grow poorly in hot and humid climate conditions. It prefers light and tolerates shade when young. Large trees require sufficient overhead light, otherwise they will grow poorly or wither. The soil requirements are not strict, and it can adapt to both acidic soil and slightly alkaline soil. Deep, fertile and loose soil is most suitable for its growth. It can also adapt to heavy loess and barren dry land. Tolerant to drought, intolerant to water and moisture. Shallow roots, poor wind resistance. It has weak resistance to sulfur dioxide. High concentrations of sulfur dioxide in the air often cause plant death, especially when new leaves appear between April and May.

Most cedars have a male-female smell. In addition, the flowering period is not the same, so the natural pollination effect is poor. In order to obtain full seeds, artificial pollination is required.

Propagation and cultivation generally use sowing and cutting propagation. Sowing can be carried out in mid-to-late March, with a seeding rate of 75 kg/ha. You can also sow seeds early to increase the seedlings' disease resistance. Choose sandy loam soil with good drainage and aeration as the seedbed. Before sowing, soak the seeds in cold water for 1-2 days, and then sow them after drying. They will start to sprout after 3-5 days and can last for about 1 month, with a germination rate of 90%. During the seedling stage, attention should be paid to shading and the damage of damping-off disease and cutworms should be prevented. Annual seedlings can reach 30-40 cm tall and can be transplanted the following spring. Propagation by cuttings can be carried out in both spring and summer. The best time is before March 20 in spring, and in late July in summer. In spring, cut off the annual thick branches of young mother trees and treat them with rooting powder or 500 mg/L naphthalene acetic acid to promote rooting. Then insert it into well-ventilated sandy loam soil, water it thoroughly, and build a double-layer shade shed for shade. In summer, it is advisable to select the semi-woody branches of the current year as cuttings. In terms of management, in addition to strengthening shading, plastic films must be covered to maintain humidity. Callus can form 30-50 days after insertion. At this time, 0.2% urea and 0.1% phosphoric acid in potassium dihydrogen solution can be used for extra-root fertilization.

The propagated seedlings can be transplanted after 1 to 2 years. Transplantation can be performed from February to March. Plants need to be covered with soil balls and supported by poles. The distance between rows of plants is gradually increased from 50 cm to 200 cm. Topdress 2-3 times during the growth period. Generally, there is no need to shape or prune branches. You only need to thin out diseased dead branches and shady weak branches close to the crown. You can spray benlate or zinc to control gray mold, and spray omethoate, trichlorfon, etc. to control scales, moths and butterfly pests.