Seedlings of coniferous plants are usually propagated in three ways: from seeds, vegetatively, and by grafting. For pine trees, the best results are achieved only through seed propagation. Vegetative and grafting methods are not sufficiently effective.
In the conditions of Uzbekistan, three types of pine are mainly used for landscaping and afforestation: Scots pine, Crimean pine, and Eldar pine. Propagation of all types of pine from seeds is not a complicated process. For this, mature and fresh seeds are required, which are located in cones on the trees. Depending on the pine species, cones should be collected at the end of October or beginning of November. At this time, the seeds are fully ripened and ready for sowing. It is recommended to collect only cones that are still hanging on the branches because those that have fallen to the ground are usually already open and their seeds have been dispersed by the wind. The collected cones should be spread out on paper or fabric and dried near heating devices (radiators, stoves, etc.). This is necessary for the cones to open and release their seeds. Fully dried cones will release seeds easily. Collecting seeds from different trees provides better results, as it allows for the selection of the highest-quality seeds for cultivation. Healthy and viable seeds are essential for good germination.
Storing Pine Seeds
Seeds should be stored in a dry and cool place, in tightly sealed glass containers. About 2–3 months before sowing, seeds are removed from the containers and damaged seeds are discarded. To test germination, place the seeds in water — those that float generally have lower viability. It is then recommended to stratify the seeds, which helps soften the seed coat and improve germination rates. For this, seeds are soaked in a 0.5% potassium permanganate solution for 30 minutes, then rinsed in clean water and soaked for 24 hours. After that, they are placed in moist sand, packed in a thin pouch, and stored in a refrigerator for about one month. Alternatively, high-quality seeds can be selected, soaked for 12–24 hours, and directly prepared for sowing, which also gives good results.
Preparing Seeds for Sowing
Containers and soil should be prepared in advance. The soil should be light, and high fertility is not necessary. Regular river sand is used, which is sterilized by heating it at 200°C for 20 minutes to eliminate bacteria and mold spores. Seeds are sown in a greenhouse during the second ten days of April. A layer of soil up to 2 cm thick may be added on top, and the seeds are placed vertically with the pointed end down, gently pressed into the soil. Then a 1–1.5 cm thick layer of fresh pine needles is spread over the top. The seeds are then thoroughly watered or misted and covered with greenhouse film or frames. Germination may begin in 8 days and continue for up to one month.
Sowing Seeds in Open Soil
In spring, seeds can also be sown directly in open soil. All steps are carried out similarly to those in the greenhouse, but the sown area is covered with agro-fabric to prevent wind and rain from washing away the soil. To protect from direct sunlight, a soft cloth or silk fabric is spread over the top. In mid-August, greenhouse covers and frames are removed, and in winter, the seedlings are covered with dry leaves. The soil where seedlings are growing should be kept moderately moist at all times. In hot weather, more frequent watering is required. Excessive moisture can lead to seed rot, so greenhouses and covers should be ventilated 1–3 times a day. During the summer, the seedlings should be fertilized three times with special conifer fertilizers — fertilization and watering are carried out simultaneously. Transplanting Seedlings
Seedlings grown from seeds are transplanted in spring after 2–3 years to individual plots at a spacing of 30–50 cm. This task must be carried out very carefully to avoid damaging the roots. During transplanting, the roots must not be shaken, as the mycorrhiza present on the roots is essential for proper plant growth. Before planting, it is recommended to dip the roots in a mixture of garden soil and humus in a 2:1 ratio. Some foresters slightly trim the root system to stimulate active root growth, but this should only be done by experienced specialists. The seedling should be planted so that the root collar (the transition point from root to stem) is positioned 3–4 cm above the soil surface. Seedlings require care for approximately four years in their new location: weekly watering, soil loosening, weeding, and the application of organic or mineral fertilizers. In the second year after transplanting, before the growth season begins in spring, a mixture of 500 g of rotted manure, 25 g of superphosphate, and 10 g of potassium nitrate is applied per square meter. Fertilizers are evenly distributed, incorporated into the soil at a depth of 10 cm, and watered. 6–7-year-old pine seedlings are planted in permanent locations in spring or early autumn. Since their roots are shallow, they adapt well to transplantation.
Propagation by Grafting
Pine trees can also be propagated through grafting. This method ensures that all the traits of the parent tree are passed on to the offspring. Plants aged 4–5 years are selected as rootstock, and scions are taken from 1–3-year-old branches. All needles are removed, except for those at the top of the rootstock. The rootstock should not have any side shoots or long branches. Grafting is carried out before the start of the vegetation period, although it can also be done in mid-summer. In spring, grafting is done onto last year’s shoots; in summer, onto current-year shoots. The side-by-side method is commonly used for grafting. This method is recommended only for experienced foresters.
Pine Diseases and Pests
If pine needles become shorter, paler, and develop white fluffy patches, this indicates the presence of a type of aphid called pine woolly aphid (Pine Hermes). To eliminate it, branches should be sprayed in May with a solution of Actellic or Rovikurt.
The gray pine aphid can also affect pines. For prevention, spray the trees with Karbofos in May (30 g per 10 liters of water). Repeat the treatment after 10 days.
Needle and branch drop is a sign of scale insect infestation. These are difficult to control due to the females being protected by hard shields. Therefore, in May–June, when larvae emerge, trees should be treated with Akarin (30 g per 10 liters of water).
Drying of branch tips, reduced growth, and needle discoloration are signs of the pine root bug. It overwinters in fallen needles, so in autumn and early spring, dust (25 g per tree) should be applied around the base of the tree. In May, treat emerging larvae with Actellic (15 g per 10 liters of water), using 0.25 liters of solution per tree. If in May the needles turn reddish-brown, begin to dry, fall off, and buds stop growing, and in summer branches dry out with smooth wounds and resin leakage — these are signs of pine canker disease. Treatment should be carried out throughout the growing season: in late April, late May, early July, and September. Use Fundazol or Antio (20 g per 10 liters of water). Spraying in warm winter days is also beneficial — in such cases, Karatan (20 g per 10 liters of water) is used.
Associate Professor of the
Department of Forestry and Landscape Design
J.M. Jurayev
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