Second, seed germination before sowing: In order to make seeds germinate quickly and orderly before sowing, it is best to accelerate germination. There are many empty seeds of Platycladus orientalis. After dividing the water, take out the floating empty seeds. Soak the seeds in 0.3%-0.5% copper sulfate solution 1-2 hours, or soak the seeds in 0.5% potassium permanganate solution for 2 hours to disinfect the seeds. Then, accelerate seed germination. There are three common methods to accelerate the germination of Platycladus orientalis seeds. 1. Mixed snow burial method: choose a place with lee, shade, good drainage and convenient management. When the snow doesn't melt after winter, mix the seeds with 3 times of snow and put them in the cellar. The barn should be surrounded by straw curtains and snow with a thickness of 10 cm, mixed with seeds and snow. Bundles of straw are wrapped around the barn to prevent the snow in the barn from melting in early spring. Keep the snow for 3-5 days before sowing and take it out. After the snow melts completely, the screened seeds are scattered in the shade to remove impurities, and then the seeds can be planted. You can also mix the seeds into fine sand before sowing 1 week, after snow melting, dry in the sun, turn over, heat and moisturize, and when 1/3 seeds crack, sieve out or mix the sand and sow in time. 2. Sand mixing to accelerate germination: When seeds are planted too late and hidden in snow or there is little snow in winter, sand mixing can be used to accelerate germination 15- 20 days before sowing. Soak the sterilized seeds in warm water for 24 hours. Then, take out the seeds, mix them evenly with fine sand twice the volume of the seeds, and put them in a wooden box without water. The temperature of seed sand is always kept at 12- 15℃, and the seeds are turned over 2-3 times a day, and warm water is sprayed at any time to keep the proper temperature and humidity to promote seed germination. When some seeds have germinated and there are 1/3 seed cracks, they can be planted. 3. Soak the seeds in warm water to accelerate germination: soak the sterilized seeds in 45cC warm water for 24 hours, and remove the floating empty seeds in combination with seed selection. Then take out the seeds, spread them on the mat at leeward and sunrise, turn them over frequently, keep the necessary humidity, and wash them with warm water 1-2 times a day. After 5-6 days, 1/3 seeds crack and can be planted.
Third, sowing: Platycladus orientalis is suitable for spring sowing, but the sowing time is different because of different weather conditions in different places. Platycladus orientalis grows slowly. In order to prolong the seedling period, according to the local weather conditions, it is advisable to sow early, such as in the middle and late March in North China, in the late March to early April in Northwest China and in the middle and late April in Northeast China. The seeds of Platycladus orientalis have many empty grains, which are usually germinated by water selection before sowing. In order to ensure the yield and quality of seedlings, the sowing amount should not be too small. When the seed purity is above 90% and the seed germination rate is above 85%, the sowing amount per mu is about 10 kg. In northern China, Platycladus orientalis is raised on high ridges or ridges, and in some arid areas, it is also raised on low ridges. Before sowing, water should be poured through the bottom, and then seeds should be pushed by hand or ditched by hand. When sowing, ridge sowing: the width of ridge bottom is 60 cm, the width of ridge surface is 30 cm, and the ridge height is 12- 15 cm. Two rows or single rows can be planted in each ridge, with the width of double row drilling being 5 cm and the width of single row drilling being 12- 15 cm. Sowing in the same bed: bed length 10-20m, bed width 1m, bed height 15cm, vertical (along the bed) drilling of 3-5 rows per bed, sowing width of 5- 10cm, horizontal drilling width of 3-5cm and row spacing of 655. When sowing, the ditching depth should be consistent and the sowing should be uniform. After sowing, the soil should be covered 1- 1.5 cm in time, and then spring pressure should be applied to make the seeds closely connected with the soil, which is beneficial to seed germination. In arid and windy areas, in order to keep soil moisture, grass can be used to cover the soil when conditions permit.
4. Seedling management: The seeds treated by accelerating germination germinate and come out about 10 day after sowing, and the peak of emergence is about 20 days, and the field germination rate can reach 70%-80%. In order to facilitate seed germination, the soil in the seed layer should always be moist, and the bottom water must be irrigated before sowing. If the soil is not too dry before the seedlings are unearthed, it is best not to cover them with water, so as not to reduce the docility and cause the surface soil to harden, which is not conducive to seedling emergence.
After the seedlings are unearthed, someone should be assigned to look after these birds. When the seedlings are all out, spray them immediately. 5%- 1% bordeaux mixture and then spraying 1 time every 7- 10 days for 3-4 times in a row can prevent the occurrence of damping-off disease. The amount of water injection should be properly controlled during the seedling growth period to promote the growth and development of roots. The fast-growing period of seedlings is just in the high temperature and drought period after the middle and late June and before the rainy season. The temperature is high and the rainfall is low. It is necessary to water them in time and increase the number of water injections appropriately, and the irrigation amount will gradually increase. According to the soil moisture, water every 10- 15 days, and it is appropriate to use sprinkler irrigation or lateral water injection on the principle of one-time irrigation. After entering the rainy season, reduce irrigation, drain water as needed to prevent waterlogging, so that internal water does not accumulate and external water does not invade. Topdressing should be combined with irrigation in the fast-growing period of seedlings. Ammonium sulfate is applied 2-3 times a year, with 4-6 kilograms of ammonium sulfate per mu, at the early stage of fast-growing seedlings 1 time, and once again after half a month. You can also use decomposed human feces for topdressing. After each topdressing, it must be watered and washed in time to prevent seedlings from burning. Platycladus orientalis seedlings must be shaded and properly kept closed. When the seedlings are too dense to affect the growth and the height of the seedlings is 3-5 cm, the seedlings should be thinned twice. After the seedlings are fixed, the number of seedlings per square meter of bed surface is about 150, and the yield of seedlings per mu can reach1500,000. Weed and loosen the soil in time during the seedling growth period to achieve "early weeding, small weeding and large weeding". Take more chemicals to weed, use 35% herbicide ether (EC), 2 ml per square meter, dilute with water and spray. Spraying 1 time after sowing or before emergence, spraying for the second time after 25 days and spraying for 2-3 times continuously can basically eliminate weeds. The dosage per mu is 0.8 kg each time. When the hardening of topsoil affects the growth of seedlings, loosen the soil in time, and the depth of loosening soil is about 1-2 cm, which should be carried out after rainfall or watering to avoid damaging the root system of seedlings. The seedlings of Platycladus orientalis should be well protected against cold in winter. In cold and windy areas in winter, first pour frozen water, then cover the soil or sandwich the wind wall to prevent the cold, or cover the grass to prevent the cold. Production practice shows that covering soil has the best cold-proof effect, which is not only simple and labor-saving, but also beneficial to the safe overwintering of seedlings. However, according to the demand, it is not appropriate to bury the soil for cold protection too early, just like before and after beginning of winter, the soil has not frozen; It is not too late to remove the cold-proof soil, and it is usually removed twice before and after Qingming after thawing; After moving the soil, make up the green water in time to prevent the seedlings from losing water and turning yellow due to the strong spring drought and wind.
Five, seedling transplantation: Platycladus orientalis seedlings out of the nursery for two years, the next spring transplantation. Sometimes, in order to cultivate green seedlings, it is necessary to transplant them for 2-3 times, and then cultivate them into large seedlings with developed roots, reflecting growth and elegant crown shape, and then plant them in nurseries. According to local experience, the survival rate of transplantation in March-April in early spring is higher, reaching more than 95%.
The transplant density depends on the culture years. Seedling raising after transplanting 1 year, plant spacing 10cm×20cm. Culture for 2 years, with row spacing of 20 cm× 40 cm; Cultivation for 3 years, spacing between plants is 30cm× 40cm; Cultivating large seedlings over 5 years old, with row spacing 1.5m×2.0m, also requires multiple transplanting, which is not only conducive to promoting the growth and development of seedling roots, but also conducive to cultivating good crown shape and stem shape, and decisively improving the land utilization rate. According to the size of seedlings, different transplanting methods are adopted, such as narrow slot transplanting, ditching transplanting and digging transplanting.
After transplanting, the management of seedlings should be timely water injection and thorough irrigation every time. When the soil moisture is suitable, measures such as intertillage, weeding and topdressing should be taken in time. Except for shaping and pruning according to the requirements of landscaping, other measures are basically the same as the cultivation of coniferous seedlings. leaf blight
The symptoms of Platycladus orientalis leaf blight occur in spring. Both saplings and forests suffer. The pathogen infects the new leaves of the year, and the shoots often show symptoms at the same time as the scales, and finally die and fall off with the scales. There were no symptoms in the year after infection, and after autumn and winter, the leaves withered rapidly in March of the following year. The incubation period is more than 250 days. Around mid-June, black particles were produced on dead scales and dead branches, which expanded into olive cups in humid weather, which is the ascus of pathogenic bacteria.
Most of the damaged scales gradually turn yellow from the top, or lose their green color from the middle of scales and stems, and then develop to the whole leaf, from yellow to brown and die. On the twig, it will turn brown and finally die. The inner and lower parts of the crown of the damaged part were serious, and the autumn shoots were basically unaffected that year.
After the victim of Platycladus orientalis, the crown of the tree withered like fire, a large number of diseased leaves fell off and branches died. Clusters of small branches and leaves germinate on the trunk or branches, and the so-called "tree beard" suffers for several years, causing the whole plant to die.
The prevention and control measures of Platycladus orientalis leaf blight should be mainly afforestation technical measures to promote the growth of Platycladus orientalis, and moderate pruning and thinning should be taken to improve the growth environment and reduce the source of infection. Conditional can increase fertilizer and promote growth. Chemical control can be carried out by using bactericide smoke agent, and good control effect can be obtained by releasing smoke at the dose of 15kg per hectare in the evening at the peak of ascospores around mid-June. Through large-scale control tests, the effect of one-time use of bactericide I and smoke agent II is over 50%. Use 40% mirex and 40% carbendazim.
leaf blight
Leaf blight of Platycladus orientalis is the main disease of Platycladus orientalis. When the damage is serious, it can cause the leaves of Platycladus orientalis to wither and burn in a large area. The tree is seriously weak, which is easy to cause secondary pests such as cypress, Monochamus alternatus and bark beetles, and accelerate the death of trees.
Occurrence law
Fungi overwinter on diseased leaves and begin to move in April of the following year. In May, it first infected from the lower leaves of the crown, and yellow spots appeared in the early stage of the diseased leaves, which gradually expanded, turning the whole cypress leaves yellow and finally yellow-brown. In June, black spots appeared on the reproductive organs of the diseased leaves, and spores were released for reinfection. If the forest is dense, the humidity in the forest is high, and the temperature is suitable, a large number of infections will spread, resulting in an epidemic situation, and the disease will be the most serious in June and July. There is often a disease center in the dense forest, which gradually spreads into pieces. In severe cases, like a fire, a large number of diseased leaves fall off. Clusters of new leaves often grow on the branches of tree trunks, which are called "tree whiskers".
Generally speaking, diseases are more serious in canyons than on the top of mountains, in shady slopes than on sunny slopes, in dense forests than in sparse forests, and in rainy and humid weather.
Prevention and cure method
1, in autumn and winter, the diseased leaves under the tree were burned and polluted. Eliminate winter germs and reduce the first invasion.
From February to August, spray 1 bordeaux mixture every two weeks for prevention, and pay special attention to strictly control the initial infection. If the initial infection center is found, it should be blocked to prevent its spread.
3, the dense cypress forest should be properly thinned, so that the forest is ventilated and transparent, reducing the incidence conditions.