A Detailed Guide to the Sowing Methods and Grafting Propagation Techniques of the Purple-leaf Bird Cherry

How do you propagate the purple-leaf bird cherry by sowing? The purple-leaf bird cherry (Padus virginiana 'Canada Red') originated abroad and is a fast-growing, light-loving plant. After many years of introduction and cultivation in the northern regions of our country, it has demonstrated the excellent characteristics of a colored-leaf tree species. Let's take a look together at the sowing and grafting propagation techniques for the purple-leaf bird cherry.

1 Sowing and seedling propagation

The bird cherry (Padus) is mainly propagated by sowing. The purple-leaf bird cherry can also be sown, but only 1/8 of the seedlings will have purple-red leaves; the other 7/8 of the seedlings must be grafted to be propagated into purple-leaf bird cherry seedlings.

1.1 Fruit harvesting, seed extraction and storage

Around mid-July, pick fully morphologically mature bird cherries that are black and nearly ready to drop. Store the purple-leaf bird cherry berries in a bucket or basin for 3 to 7 days to let them soften and rot thoroughly, then spread them on the ground and tread on them to separate the flesh from the seeds. Put them into a container, add water several times, rub and rinse, pour off the floating material, and take out the plump, viable seeds that have sunk to the bottom of the container. If you plan to sow in autumn, mix the seeds with moist sand and store them in a cool, shaded place; if you plan to sow the following spring, dry the seeds in the shade for 5 to 7 days, then put them in a sand bag and store them in a dry place.

1.2 Sand storage and germination promotion treatment of seeds

For those preparing to sow in early spring of the following year, soak the dry seeds in cold water for 36 to 48 h in early December, mix them thoroughly with 3 to 4 times their volume of river sand with a moisture content of about 25%, put them in bags and store them in mountain caves, vegetable cellars, or at the foot of the rear wall of tall buildings at -5 to 5°C, covering them with 20 cm of soil. When a small number of seeds are seen germinating in early April of the following year, they are ready for sowing.

1.3 Seedbed preparation

From late October to early November, before the soil freezes, or in early April of the following year after the soil thaws, choose a relatively flat plot of loamy soil or gentle slope land to make the bed. On flat ground, mainly use a north-south bed orientation; on sloping land, the bed orientation follows the slope aspect. The bed width is 0.8 to 1.2 m, the bed length is 5 to 10 m, and the bed height is 6 to 8 cm. Spread a 1 cm thick layer of farmyard manure or a 0.2 cm thick layer of dried chicken manure and livestock manure evenly over the bed surface, then turn the soil to a depth of 15 cm so that the soil and manure are fully mixed. Break up clods of soil, rake the bed surface level, and firm the bed edges. The path width is about 30 cm.

1.4 Sowing

The suitable period for autumn sowing is from October to early November, and the suitable period for spring sowing is April. Along or across the bed orientation, open furrows 3 to 4 cm deep on the bed surface, with a furrow spacing of 20 cm. Sow the seeds in spots or broadcast them in the furrows, with a seed spacing of 4 to 5 cm and a sowing rate of 4 to 5 g/m2, covering with soil to a thickness of 2.5 to 3 cm.

1.5 Management in the year of sowing

After sowing, cover the bed surface with a 0.5 to 1 cm thick straw mat with a porosity of about 40% or other covering material. Spray water onto the covering to moisten the soil particles on the bed surface to a depth of 5 to 8 cm. After 5 to 7 d, spray water a second time. Remove the covering promptly after seedlings emerge, and spray water promptly during the growing season if there is excessive drought. From June to August, if aphids harm the leaves, spray 40% dimethoate 1500 times dilution to kill them. From May to September, pull and hoe out weeds several times. In early November, if you do not plan to dig up the seedlings, irrigate once with overwintering drought-prevention water.

2 Grafting and management

2.1 Transplanting before grafting

Seedlings sown in the current year are transplanted in late October of that autumn or in April of the following year. Choose gentle slope land or flat land with sandy loam soil, spread farmyard manure evenly over the surface at an application rate of 3 m3/667 m2, turn the soil to a depth of 20 cm, and form ridges with a ridge spacing of 60 cm and a ridge height of 20 cm. Open a furrow about 8 cm deep along the center line of the ridge, and transplant the root-trimmed seedlings upright at a plant spacing of 10 to 15 cm, firming the soil and watering thoroughly. Transplanting in late autumn allows faster recovery of the seedlings the following year; those with a ground diameter reaching more than 0.5 cm can be grafted in early April of the following spring. Spring transplanting should be done as early as possible, preferably from late March to early April, with grafting prepared for in early to mid-May. Sown seedlings with a ground diameter of less than 0.3 cm need to be bud-grafted in August of the following year or grafted onto branches the spring after that.

2.2 Hardwood grafting

2.2.1 Cleft grafting. The suitable period is from early April to early May. From February to March, cut fully lignified 1-year-old branches with a diameter greater than 0.4 cm, store them in a cool place at -10 to 5°C, and seal and bury them with moist sand. Preparing the scion: the scion length is 5 to 7 cm; when scions are plentiful, keep 2 buds, and when they are scarce, keep 1 bud. At the lower end below the lower bud, cut 2 straight, flat wedge-shaped cut surfaces about 2.5 cm long. Cutting the rootstock and making the cleft: cut off the rootstock at 3 to 10 cm above the ground, and at the center or one side of the cut end, use scissors to make a vertical cut about 2.5 cm long. Inserting the scion: insert the scion with the thick end of the cut surface facing outward into the cleft of the rootstock, aligning the cambium on one side or both sides. Tying: use a 1.5 cm wide plastic strip to wrap and bind the joint tightly. Hardwood cleft grafting: the suitable rootstock thickness is 0.4 to 1.2 cm, and the scion thickness is from 1/3 of the rootstock thickness to equal thickness.

2.2.2 Bark grafting. The suitable period is from late April to mid-May, when the bark of the rootstock section slips, and the scions should be cut from February to March and stored in a cool place. Preparing the scion: the scion cut is 6 to 8 cm long and has 1 to 2 buds. Cutting the rootstock: cut the rootstock flat at 4 to 10 cm above the ground. Inserting the scion: insert the scion with its cut surface facing inward between the bark and the wood of the rootstock, so that the scion cut surface fits tightly against the rootstock wood. Tying: use a 2 cm wide plastic strip to wrap and bind the joint. The suitable rootstock thickness is 0.6 to 1.2 cm, and the scion thickness is from 1/3 to 2/3 of the rootstock thickness. Generally, seedlings sown the previous year are often unsuitable for bark grafting because their thickness is relatively small; for rootstocks more than 3 years old, bark grafting is used more often.

2.3 Bud grafting

2.3.1 Bud grafting with wood. Using buds on new shoots for bud grafting with wood, the suitable period is from June to July and in early September. Cutting the bud piece: after cutting new shoots from the purple-leaf bird cherry plant, graft immediately, leave a 0.5 cm long petiole, and at 1 cm above the bud, make a cut at an angle of 10° to 15° down to 1 cm below the bud; at 1 cm below the graft bud, cut into the wood at an angle of 30° so that it intersects with the upper cut, and snap off the bud piece with wood. Cutting the rootstock notch: at 3 to 10 cm above the ground on the rootstock, on a smooth, light-facing southwest side, cut a notch from top to bottom, with a length and depth the same as or similar to the bud piece with wood. Attaching the bud piece: place the cut surface of the graft bud against the notch of the rootstock, aligning the cambium on one side. Tying: use a 1 cm wide plastic strip to wrap and bind the graft bud piece, leaving the bud and petiole exposed. In addition, in production, buds on 1-year-old branches can also be used for bud grafting with wood, but the survival rate is relatively low and it is not used much.

2.3.2 Shield bud grafting. Also called T-budding, the suitable period is from July to August, and it is most used from the Start of Autumn to early September. Cutting the bud piece of the scion: remove the leaves, leave a 0.5 cm long petiole, make a ring cut through half a circle of bark at 1 cm above the bud, then at 1 cm below the bud, cut upward into the wood at an angle of 10° to 15° to intersect with the upper cut, and snap off the bud piece. Cutting the T-notch in the rootstock: at 3 to 10 cm above the ground, mainly on the southwest side, on a smooth, light-facing spot, cut a T-notch through the bark. Inserting the bud piece: open the T-notch, insert the bud, and join it with the upper horizontal cut. Tying: use a 2 to 2.5 cm wide plastic strip to wrap and bind the joint, and the bud should be left exposed.

2.4 Management in the year after grafting

2.4.1 Keeping scions fresh and preventing drying. In combination with grafting operations, during hardwood grafting, wrap and seal the top cut and the surrounding area of the scion with plastic strips, leaving the bud exposed. After grafting, you can also apply a special fruit-tree moisturizer diluted 1 to 2 times with water to the cut and surrounding area. You can also cover it securely with a plastic bag, and after the bud sprouts and leaves unfold, puncture holes for ventilation for 1 to 2 days, then remove the bag.

2.4.2 Cutting the rootstock. For bud grafting from June to July, after the graft bud survives, cut off the rootstock 1.5 cm above the graft bud. For bud grafting from August to September, cut off the rootstock 1.2 cm above the graft bud around Qingming of the following year.

2.4.3 Removing rootstock sprouts. When the buds on the scion sprout and grow to 2 to 15 cm, begin removing rootstock sprouts, wiping or cutting off the buds or shoots growing on the rootstock, cutting once every 7 to 10 days, about 5 to 6 times.

2.4.4 Cutting the ties. When the buds on the scion grow to 10 to 30 cm, use a sharp knife to cut the binding strip. Some nurseries do this to prevent wind from breaking the new shoots.

3 Large seedling cultivation

3.1 Land preparation

In October of the year of sowing and seedling raising or in early April of the following year, choose a plot of medium loam to light clay soil, clear away debris, spread farmyard manure evenly in surface furrows at an application rate of 2500 kg/667 m2, plow the soil to a depth of 15 to 20 cm, and form ridges with a ridge spacing of 0.8 cm and a ridge height of 20 cm.

3.2 Transplanting in the nursery

After land preparation in October or April, dig holes 8 to 10 cm deep along the center line of the ridge at a hole spacing of 0.4 cm, plant ungrafted bird cherry seedlings or grafted purple-leaf bird cherry seedlings in the holes, firm the soil and water thoroughly, making sure they survive. In the 3rd to 4th years, keep plants at a plant spacing of 0.8 cm and transplant the remaining plants. In the 5th to 6th years, again keep and transplant plants at a row spacing and plant spacing of 1.6 m x 1.6 m. The age of transplanted plants should also be determined flexibly according to the size of the crown.

3.3 Routine management

From after transplanting until large seedlings leave the nursery, during each year's growing season, weeds should be removed promptly by manual or chemical methods to ensure that seedling growth is not affected by weeds. From May to August, if sap-sucking aphids or leaf-eating caterpillars cause damage, spray omethoate 2000 times dilution to kill them. In case of excessive drought, water promptly. As tree age and crown width increase, from February to March prune out branches growing from the lower half of the trunk from the base, so as to cultivate a single-trunk, naturally rounded crown; when plant height reaches more than 2.5 m, crown width reaches more than 1.5 m, and trunk thickness reaches more than 4 m, they can leave the nursery.

That is all for today's content on planting the purple-leaf bird cherry. If you also want to grow this tree species, then hurry to Huinong Network to learn its related planting techniques first!

Cultivation and management of the purple-leaf bird cherry

Propagation and management of the purple-leaf bird cherry

    The purple-leaf bird cherry can be propagated by sowing, grafting and cuttings. For sowing propagation, seeds should be collected from purple-leaf bird cherry plants, but at present there are no pure purple-leaf bird cherry seeds. After the existing seeds are sown, only 50-60% are bird cherries with purple leaves, so grafting propagation is currently the best method for propagating the purple-leaf bird cherry.

    If seeds of the bird cherry are used for sowing, bud grafting or branch grafting can be done in the same year or the following year, and the survival rate can reach more than 90%. Cutting propagation is also a good method for propagating the bird cherry. Semi-mature branches of the purple-leaf bird cherry can be used for cuttings in June to July. The branches are treated with a root-promoting hormone to promote root growth or with 3A rooting powder No. 3 or No. 4 from the Beijing Botanical Garden of the Chinese Academy of Sciences before cutting, and the rooting rate can reach 50-60%.

    The purple-leaf bird cherry likes light. In a semi-shaded growing environment, its leaves rarely turn purple-red. When planted in Jilin and other places, it can tolerate low-temperature environments exceeding minus 40°C with no freeze damage. Under the short-term high heat of 40°C for several consecutive years in Beijing, it also grows normally. Its root system is well developed, it is drought tolerant, and it has strong resistance; it grows well in the Beijing Botanical Garden without watering for many years.

    But the purple-leaf bird cherry still prefers a warm, humid climate environment. It grows robustly on moist, fertile, loose and well-drained sandy loam soil. A 4-5 year old small tree can have an annual growth increment of more than 1 m, and a grafted seedling of the current year can grow to more than 2 m tall. The purple-leaf bird cherry has relatively few pests and diseases; in recent years, only the yellow slug moth and a small number of red spiders have caused damage.