Planting techniques of Poplar

White poplar, also known as poplar, silver poplar, etc., is a deciduous tree of the poplar family poplar, with strong survivability. It exists on the roadside and beside the ridges of the fields where there is loess, and the trunk is slender and erect, up to 20 meters high. it can be used as firewood, furniture, purlin beams and farm tools, which is of great cultivation value. Let's take a look at poplar planting techniques.

Cultivation value of Poplar

Poplar has a strong adaptability, the tree shape is tall, the silver leaves shake in the breeze and shine in the sun have a special flickering effect, the appearance is straight and clean, it has a certain ornamental value, and can be used as shade trees and street trees in the lawn. It can also be used as sand fixation, soil protection, rock protection, embankment and barren sand afforestation. In addition, there is medicinal value, extract from poplar (including salicylic acid), can relieve pain and fever, poplar bark has the effect of expelling wind, removing blood stasis, eliminating phlegm, treating wind arthralgia, beriberi, blood stasis, dysentery of pregnancy, toothache, mouth sores and other diseases.

Growth habits of Poplar

Poplar trees like light, do not tolerate shade, withstand severe cold, and have no frost damage at minus 40 degrees. Resistant to dry climate, but not resistant to hot and humid, southern cultivation is prone to diseases and insect pests, and the trunk is often curved in the shape of a shrub. Light alkaline soil tolerant to poverty, tolerant to soils with salt content less than 0.4%, but growing poorly in clayey soils. Deep root, developed root system, strong soil consolidation ability and strong root tiller. The ability to resist wind and insect pests is strong, and the life span is more than 90 years.

Site selection of Poplar

The selection of forest land suitable for poplar growth is the basic condition to realize rapid growth and high yield of poplar. Poplar is a fast-growing species of deciduous broad-leaved trees, which grows best on alluvial soil with deep, loose, fertile, moist and well-drained soil, with flat terrain or slope below 15 °and effective soil layer thickness of more than 0.7 meters. Land with irrigation conditions. The soil texture of light loam and sandy loam is the best, followed by middle soil, and Populus tomentosa can grow on heavier soil. The groundwater level suitable for growth should be about 1.5 meters, and the groundwater level should be less than 1 meter during the growing period. The content of soil nutrients is high, and the minimum content of organic matter is more than 0.4%. The soil ph value is 6: 8, the soil salt content is less than 0.1%, and the gravel content is less than 20%.

Land preparation and afforestation of poplar

Soil preparation is carried out before the soil is frozen, land leveling is carried out according to the topography, comprehensive land preparation with machine ploughing and complete reclamation is carried out, with a depth of more than 30 cm, or local soil preparation of banded and anti-slope terraces, and then 80 cm square planting holes are excavated. when digging holes, the topsoil is stacked separately from the subsoil. The woodland with good site conditions, the varieties with fast growth and larger crown, and those with large diameter wood have lower density. The site condition is poor, the varieties with straight stem shape and narrow crown shape are selected, and the density can be higher when cultivating stands with short rotation. The suitable row spacing is 2 × 4 m, 3 × 4 m, 4 × 5 m and 4 × 8 m in pure forest, and 1 × 2 × 12 m and 1.5 × 2 × 8 × 10 m in the plain where agroforestry is carried out.

Planting techniques of Poplar

1. Seedling treatment: in all aspects of seedling raising, transporting and planting, it is necessary to prevent seedling water loss. In the seedling field, the principle of irrigation before seedling should be followed. In the start and transportation of seedlings, attention should be paid to protecting the root system, making the root system complete, fresh and moist, and planting with it as far as possible. Seedlings that can not be planted in time should be planted properly. Some clones of American black poplar should be soaked in clean water for 1-2 days before planting. Before afforestation, the long root should be amputated, and the lateral root length is generally maintained at 30 cm (too long is easy to appear in planting). For the seedlings in which some terminal buds or even tips are damaged, the top tips should be cut off and cut back to 1 cm above the first strong bud in the uppermost part when pruning.

2. Seedling planting: it is suitable for poplar afforestation in spring and late autumn and early winter (late October to mid-November), after poplar defoliation, before soil freezing and before sprouting in spring. The planting depth is determined according to the soil conditions, and it is appropriate to plant about 60 cm on the dry and loose soil, which can increase the rooting amount of seedlings and improve the ability of drought and wind resistance, but it is not suitable for deep planting in the clayey soil and low-lying land. During afforestation, it is required to plant large holes, straighten, straighten, fill the soil by layers, step on the soil layer by layer, make the roots of the seedlings stretch and connect with the soil, water immediately after planting, strengthen the seedlings after water infiltration, and cultivate the soil to seal the holes.

Tending and Management of Poplar

1. Timely irrigation: in addition to the newly built young forest, it is necessary to irrigate the stand in the dry season from April to June to ensure the exuberant growth of trees. Irrigation should also be carried out in autumn drought. Winter irrigation of American black poplar and other varieties can improve the ability of drought and cold resistance of trees. The number of irrigation and the amount of irrigation depend on the weather and soil conditions. Generally, before and after spring tree sprouting, growing season and soil freezing, water should be watered in time according to soil moisture and rainfall. After watering, soil moisture should be cultivated in time to preserve soil moisture.

2. Rational fertilization: before afforestation, 1500 kg of soil miscellaneous fertilizer and 50 kg of superphosphate were applied per mu, and then mixed into the range of root planting depth in the dug tree hole. From May to June every year, topdressing is applied twice in the peak growth period of poplar, and the amount of fertilizer each time is 3kg of urea or 12kg of ammonia bicarbonate. It can be applied late or less in the year of afforestation, and can be applied more appropriately with the increase of forest age, and pay attention to the combination of nitrogen, phosphorus and potassium. Topdressing should be combined with watering.

3. Loosening soil and weeding: weeding should be done not less than twice a year before forest canopy is closed, and intercropping can be combined with crop management. The times of weeding can be reduced appropriately after the stand is closed. During the period of agroforestry intercropping, the soil should be loosened at least once or twice a year after stopping intercropping, so as to loosen the soil and prevent soil consolidation.

4. Reasonable pruning: timely pruning can improve the quality of the trunk and help to cultivate high-quality wood with perfect stem shape. All the lateral branches of the seedlings were trimmed during afforestation, and the young trees 1-3 years after afforestation, the competitive branches were removed, the auxiliary branches were retained, and the sprouting shoots at the base of the trunk were cut off to cultivate an upright and strong trunk. The pruning intensity should keep the ratio of crown length to tree height above 3 × 4. The plywood should not have a scar, and pruning should be carried out when the trunk at the base of the first round of side branches reaches 10-12 cm, and the first round of side branches should be removed to cultivate knot-free wood. Pruning should be carried out after the trees have fallen leaves in autumn. the cut should be smooth and the branches should not be torn, and the weak branches in the lower layer of the crown should be gradually removed from the trees after four years.

5. Agroforestry intercropping: ploughing instead of caressing, and implementing agroforestry intercropping before the stand is closed can not only improve the utilization rate of land, but also cultivate young forests through measures such as loosening soil, weeding, watering and implementing, etc. promote forest growth, increase income, intercropping crops should be short, shade-tolerant, less water and fertilizer consumption of soybean, peanut and other leguminous crops or melons, medicinal materials, wheat and so on. Intercropping crops and trees should be kept at a distance of more than 50 meters, so as not to damage the roots of trees or crops to compete with trees for water and land.

Control of diseases and insect pests of poplar

1. Forest management measures: first of all, we should advocate suitable land and suitable trees and build a mixed forest. Paulownia, Robinia pseudoacacia, Toona sinensis, Toona sinensis, Albizia mandshurica, Liriodendron and jujube, apple, pear and poplar can be selected for block mixing or banded isolation, and strong seedlings with strong insect resistance can be selected for afforestation. The second is to strengthen tending management, timely carry out ploughing, loosening soil, weeding, fertilization, and pruning in the appropriate season to enhance the tree potential and improve the stand's ability to resist diseases and insect pests.

2. Biological control: when the pest occurrence area is large, Zhou's wasp or Trichogramma can be released in the early stage of pest spawning for control. Or hang bird nests in the forest to actively attract beneficial birds and increase the number of birds. Or use knapsack type motor sprayer, stretcher type motor sprayer to spray 25% diflubenzuron 2000 times liquid for ground spray prevention and control. The road forest, forest net and piece forest with a certain canopy density can be controlled by spraying Sendelbao powder with knapsack motorized dusting machine. For the occurrence of large area concentrated tablets, ultra-low amount of 25% diflubenzuron 600 g / ha can be used to control.

3. Physical control: during the overwintering (overwintering) period of pests, the artificial collection of fallen leaves or ploughing soil and the removal of egg blocks, bracts or cocoons can reduce the number of overwintering (oversummer) pests and the peak emergence of adults. You can hang insecticidal lights (black lights) in the forest or light a fire at the edge of the forest to trap and kill adults.

4. Chemical control: spraying smoke on the ground or releasing smoke can be used to control the young and middle-aged forest with a height of less than 12 meters, which is suitable before the stage of the 3rd instar larvae. 80% trichlorfon 800-fold liquid and other high-efficiency, low-toxic and environment-friendly chemicals were sprayed by stretcher, knapsack motor sprayer or vehicle-mounted machine. 6hy and or series smoke machines can be used to spray EC or oil with contact, gastrotoxicity or fumigation for smoke control of road forest, forest net and piece forest with a certain canopy density, the mixture ratio of chemical and diesel is 1:10, or Lindane smoke agent or diphtherine smoke agent is used for smoke control, the smoke dosage is 1 kg / mu. In the case of local occurrence and damage to tall trees, 10% imidacloprid with strong permeability and long duration can be used to cut the wound around the trunk at the breast diameter of the trunk or scrape off the bark of the old tree and then apply the poison ring. You can also use dry base hole injection, use tools such as drilling machine or manual drilling to drill 3 or 4 holes in different directions at the base of the trunk, and inject 10% imidacloprid EC with strong internal absorption and conductivity, 40% omethoate EC and so on. The dosage is 2ml / 10cm chest diameter, raw drug or 1 Mel 3 times diluent. After injection, pay attention to seal the mouth of injection.