A Detailed Guide to the Latest Planting Techniques and Methods for Lacebark Pine
The lacebark pine (Pinus bungeana) is an evergreen tree of the genus Pinus in the family Pinaceae, reaching up to 30 m in height and 2 m in diameter at breast height. It is a sun-loving species, and young trees tolerate partial shade; its cold hardiness is inferior to that of the Chinese pine, but its tolerance of drought, moisture and adaptability to soil are all stronger than those of the Chinese pine. It can adapt to a dry, cold climate of -30°C and soil with a pH of 7.5 to 8; it can grow in limestone areas, but cannot grow in poorly drained or waterlogged places, and it has strong resistance to pollution from sulfur dioxide and smoke and dust. It is deep-rooted and long-lived. The branches of young trees are naturally distributed, dense and even, so no pruning or shaping is needed to form a beautiful crown. It grows rather slowly: one-year-old seedlings are only 3 cm to 5 cm tall, and after 10 years they reach about 1 m in height.
Growth Habits of the Lacebark Pine
It grows at elevations of 500-1800 m. It is a light-demanding species, tolerant of poor soil and a relatively dry, cold climate; it grows well on cool, mild sites with deep, fertile, humus-rich calcareous soil and loess.
The lacebark pine is a species endemic to China, produced in Shanxi (Luliang Mountains, Zhongtiao Mountains, Taihang Mountains), western Henan, the Qinling Mountains in Shaanxi, southern Gansu and the Maiji Mountain in Tianshui, the Guanwu Mountain in Jiangyou, northern Sichuan, and western Hubei, among other places. It is also cultivated in Suzhou, Hangzhou, Hengyang and other places.
Propagation Techniques for the Lacebark Pine
1. Seed propagation: The lacebark pine is generally propagated mostly from seed. The nursery site should preferably be well-drained, flat land with deep sandy loam soil. Sowing immediately after the soil thaws in early spring can reduce damping-off of pine seedlings. Because it is afraid of waterlogging, high-bed sowing should be used; water the bed thoroughly before sowing, and use about 1 kg of seeds per 10 sq m, which can produce 1000 to 2000 seedlings. After broadcast sowing, cover with 1 to 1.5 cm of soil and cover with plastic film, which can increase the germination rate. After the seedlings have emerged completely, gradually increase the ventilation time until the film is removed entirely. After sowing, the seedlings emerge with the seed shell attached, which falls off on its own after about 20 days; during this period, bird damage must be prevented. During the seedling stage, a shading frame should be set up to prevent sunscald, and before winter the soil should be mounded up for cold protection. Small seedlings have a long taproot and few lateral roots, so when transplanting, care should be taken to injure the lateral roots as little as possible, otherwise they are prone to withering and dying.
2. Grafting propagation: If softwood grafting is used for propagation, the softwood shoots of the lacebark pine should be grafted onto older Chinese pine rootstock. When lacebark pine softwood shoots are grafted onto 3- to 4-year-old Chinese pine rootstock, the survival rate generally reaches 85% to 95%, with strong affinity and fast growth. The scion should be selected from robust new shoots, with a thickness of 0.5 cm being preferable. When bare-root transplanting 2-year-old seedlings, the root system must be well protected to avoid drying out and damage; they should be dug and planted immediately, and thereafter divided and replanted every few years to promote the growth of fibrous roots, which helps the seedlings survive after planting out. For general landscaping, large seedlings over 10 years old are used. Transplanting is best done during the dormant period in early winter and when the soil thaws in early spring; when using large seedlings, they must be transplanted with a soil ball. To plant large seedlings with a diameter at breast height of less than 12 cm, a soil ball 120 cm high and 150 cm in diameter must be dug, bound with straw rope to hold the soil together, taking care to prevent the soil ball from breaking during transport, and after planting, stakes should be set up and ties used for support.
Field Management Techniques for the Lacebark Pine
1. Site selection and land preparation: Choose a good nursery site. Lacebark pine seedlings are afraid of waterlogging, so the nursery land should be chosen as flat plots with irrigation and drainage conditions. Heavy clay land, saline-alkali land and low-lying waterlogged land are not suitable as nursery land. Prepare the land carefully: the nursery land should be deeply plowed, leveled and raked fine, with sufficient basal fertilizer applied, such as rotted barnyard manure or compost. Superphosphate can also be mixed with cake fertilizer or farmyard manure for better results. Before land preparation, spread 10 kg of ferrous sulfate powder per mu, and plow it into the soil for sterilization and disinfection. After the land is prepared, make beds running north-south, with bed ridges 25 cm high and beds 1 m wide, ready for sowing.
2. Seed germination: Lacebark pine seeds should be soaked and disinfected with Bordeaux mixture; before sowing, soak the seeds in warm water (50°C to 60°C) for germination, or stratify them with sand for germination. When the number of cracked seeds reaches 50% of the total, sowing can begin. In this way, seedlings emerge robustly and evenly, generally sprouting above ground in 15 to 20 days.
3. Sowing and raising seedlings: Sowing is generally best done 10 to 15 days after the soil thaws (late March to early April). Before sowing, water the bed surface thoroughly, sow 1 to 1.5 kg per 10 sq m, which can produce about 1500 seedlings, using wide-row drilling or broadcast sowing. After sowing, cover with 1 to 1.5 cm of fine sandy soil. Per mu, use 125 g of prometryn plus 250 g of 25% wettable nitrofen, mix with 25 kg of water, and spray it on the seedbed with a sprayer for weed control. Finally, build a small arched shed over the bed to increase temperature and retain moisture, improving the emergence rate; do not water before emergence. Because mice like to eat pine nuts, before covering the arched shed with film, scatter some rat poison on the bed surface.
4. Seedling stage management: After the seedlings have emerged completely, gradually increase the ventilation time of the seedbed, hardening the seedlings to enhance their resistance. The lacebark pine likes light, but the seedlings are relatively shade-tolerant; after removing the film, a shade net should be put up at once to prevent damage from high-temperature sunscald and damping-off.
Fertilizer and Water Management Techniques for the Lacebark Pine
In long droughts without rain or during high summer temperatures, water promptly. For weeding, follow the principles of weeding early, weeding small and weeding thoroughly; pull weeds between plants by hand to avoid damaging the seedlings. After weeding broadcast-sown seedlings, cover the soil appropriately to prevent cracks. For drilled seedlings, combine weeding with loosening the soil, and carry out thinning and gap-filling at the same time. Then drain promptly.
For lacebark pine seedlings, basal fertilizer should be the main approach, with topdressing as a supplement. From mid-May to the end of July, during the peak growth period, carry out 2 to 3 topdressings, mainly with nitrogen fertilizer: apply rotted human or pig manure at 3 dan per mu, mixed with about 20 dan of water; rotted cake fertilizer at 5 to 15 kg per mu, mixed into about 15 dan of cake fertilizer water; and apply about 4 kg of urea per mu. In the late growth stage, stop applying nitrogen fertilizer and increase the application of phosphorus and potassium fertilizers to promote lignification of the seedlings; a 0.3% to 0.5% potassium dihydrogen phosphate solution can also be sprayed on the leaves.
Lacebark pine seedlings grow slowly and are suitable for dense planting. If larger-sized seedlings are to be further cultivated, 2 to 3 more transplantings are needed before planting out. Two-year-old seedlings can be transplanted with soil in early spring before the terminal buds begin to sprout, at a spacing of 20 to 60 cm, without damaging the terminal buds; after planting, water twice in succession, and water again after 6 to 7 days. For 4- to 5-year-old seedlings, a second transplanting with a soil ball can be carried out, at a spacing of 60 to 120 cm. After they survive, keep the soil around the roots loose, apply 100 to 120 kg of rotted organic fertilizer per plant, water thoroughly after covering with soil, and thereafter strengthen management to promote growth and cultivate robust seedlings.
Pest and Disease Control Techniques for the Lacebark Pine
For pest and disease control: after sowing, beware of seed flies, whose larvae damage the seedlings; the basal fertilizer applied must be fully rotted and crushed. The pine aphid damages the young branches and needles of the seedlings, and readily causes black mildew, weakening the tree and even killing it. Control method: in the early stage of damage, spray 50% phoxim emulsion, with each kilogram mixed with 2000 kg of water.