Purple-leaf plum, also known as red-leaf plum, is a deformation of the small deciduous tree cherry plum of the genus Prunus in the Rosaceae family. The crown is round or oblate, and the branchlets are reddish brown. The leaves are ovate or obovate, with heavily serrated edges, and are purple-red. The flowers are solitary or in groups of 2 to 3, pink. The fruit is nearly spherical, yellow-green with purple halo. The flowering period is from April to May, and the fruit ripening period is from June to July. The leaves are smooth, ovate to lanceolate, purple-red. Flowers are small, pale pink to white. Drupe is spherical, purple-red. Originally native to southwest Asia, it is now widely cultivated in North China and the south. It is an important tree species for landscaping and sightseeing orchards. Its cultivation and management techniques are introduced as follows.

1. Selection of planting environment

Purple-leaf plum is a warm temperate tree species that likes light. It should be planted in a place with sufficient sunlight. It should not be planted in the shade or under a big tree. Insufficient light will not only It will cause poor plant growth and cause the leaves to turn green. Purple-leaf plum is drought-tolerant and moisture-loving, but not intolerant to stagnant water. It can grow normally when planted in dry places, but will not grow well when planted in low-lying places. Purple-leaf plum has no strict soil requirements and prefers fertile, moist neutral or acidic sandy loam. It can also tolerate mild saline-alkali soil and can grow normally in mildly saline-alkali soil with a pH value of 8.8 and a salt content of 0.2%. . Purple-leaf plums are more cold-tolerant, but they should be planted in leeward and sunny locations as much as possible, and should not be planted in the wind. The leaves of purple-leaf plums are purple-red. When planting, you should be careful not to follow the color. Only the difference in color can show the beauty of the leaf color.

2. Water and fertilizer management

Purple leaf plum likes a humid environment. In addition to watering the newly planted seedlings, they should also be watered in April, May, June and September. Water thoroughly 1-2 times a month. There is abundant rainfall in July and August. If it is not too dry, there is no need to water. When there is a lot of rain, water should be drained in time to prevent water damage and root rot. In early and mid-November, you should also water enough and thoroughly to seal the frozen water. In the second year of management, watering should also be done once in early March, April, May, June, September and early to mid-November. From the 3rd year onwards, it only needs to be watered enough in early spring and early winter every year to ensure natural growth. It should be noted that watering must be controlled in autumn to prevent excessive water from causing the branches to grow elongated and suffer freezing damage in winter.

For purple-leaf plums, in addition to applying an appropriate amount of decomposed and fermented ring fertilizer at the bottom of the pit when planting, some farmyard manure can be applied every year before pouring the frozen water to make the plants grow vigorously and have bright leaves. . However, it should be noted that although purple-leaf plums like fertilizer, they only need to be fertilized once a year in late autumn, and the amount must be appropriate. If fertilized too often or in too large a quantity, the leaf color will be dark and not bright. , reduce the ornamental value.

3. Shaping and pruning

The best tree shape of purple-leaf plum is "evacuated and layered". This kind of tree shape has an open yet compact crown, an obvious trunk, and well-proportioned main branches.

Purple leaf plum plastic surgery is usually carried out every 4 years. Pruning in the first year is carried out after planting. Shorten the main trunk at 0.8-1.2m. The first bud under the cut will be used as an extension of the main branch. In addition, 3-4 thick new shoots will be selected below the first bud. As the main branches, the branches should be evenly distributed and may not be on the same trajectory, but the difference between the upper and lower branches should not be more than 5cm, and they should be spread upward at a 450° angle. After the main branches are selected, they should be appropriately topping during the growth period to promote their strength. When pruning in the second year of winter, the main branches and extension branches should also be shortened appropriately. Strong buds should be selected and cut 1cm above them. The direction of the buds should be opposite to the direction of the extension branches of the main trunk in the previous year. The main branches should also be shortened. , leaving thick outer buds. When pruning in the third year of winter, the main trunk extension branches are in the opposite direction to the main trunk extension branches in the second year, and the second layer of main branches are selected to retain the outer buds. When they grow up, they are staggered with the main branches in the second year. In the fourth year, select the third layer of main branches according to this method.

In actual work, the "natural open shape" is also widely used. The pruning method is: after the seedlings are planted, cut them short at a stem height of 0.5-1m to prevent them from growing into extensions of the main branches. Only select 3-5 new branches as main branches. The distribution of the remaining main branches should be roughly Evenly, with an opening angle of 45°, and then prune the main branches year by year according to the "evacuated and layered" method of pruning the main branches. Although this kind of tree shape is not as beautiful as the "scattered and dispersed shape", it has better permeability than the scattered and layered tree crown, and the viewing effect is also good.

It should be noted that no matter what kind of tree shape it is, when pruning the main branches at each layer, a certain number of side branches should be appropriately retained to make the crown full but not hollow. When the tree shape is basically formed, Finally, you only need to prune off overly dense branches, drooping branches, overlapping branches, crossing branches and dead branches every year.

4. Pest and disease control

4.1 Pests: The main pests of purple-leaf plums include red spider mites, thorn moths, bag moths, leafhoppers, aphids, scale insects, etc. You can spray 40% dicofol emulsifiable concentrate 1000 times to kill spider mites, use BT emulsion 1000 times to kill thorn moths and bag moths, use 10% imidacloprid 1500 times to kill scale insects and leafhoppers, and use BT emulsion 1000 times to kill scale insects and leafhoppers, and spray aphids 500 times. Kill aphids.

4.2 Diseases: Purple-leaf plum has strong disease resistance. The common disease is bacterial perforation. This disease is common and serious. After the onset, it not only affects the normal growth and ornamental effect of the plant, but also affects the severe cases. It can also cause the death of diseased plants.

4.2.1 Symptoms: When the disease first occurs, water-soaked small brown spots begin to appear on the leaves, and then gradually expand into purple-brown round or polygonal lesions about 2cm in diameter, with light yellow spots around the lesions. Halo, eventually the lesions gradually dry up and fall off into hole-like shapes.

4.2.2 Occurrence pattern: The disease is caused by infection by Xanthomonas campestris peach and plum perforation species. The fungus overwinters in diseased spots and buds on branches. In the spring of the second year, the diseased tissue overflows with pathogenic bacteria, and the infection is spread by rain, airflow and insects. The growth temperature of the pathogen is 5℃-35℃, and the optimal temperature is around 25℃. On continuous rainy days or when there is serious damage from insects such as aphids, it is easy to cause a large-scale epidemic. In central Shandong, the disease usually occurs in May, and the high temperature and high humidity period in summer is the peak period of the disease.

4.2.3 Prevention and control methods: Reasonable pruning to facilitate plant ventilation and light transmission; pay attention to the prevention and control of aphids, scale insects and other insects with sucking mouthparts; strengthen water and fertilizer management, avoid accumulation of water in the planting hole, and pay attention to fertilization Nutritional balance, pay special attention to the application of phosphorus and potassium fertilizers; spray 5 Baume degrees lime sulfur mixture or 1:1:100 equivalent Bordeaux mixture before germination in spring to eliminate the source of bacteria; spray 95% fungizolin or 15% in the early stage of the disease Streptomycin wettable powder 500 times solution, sprayed once every 10 days, and sprayed 3-4 times continuously can effectively control the disease.

5. Propagation methods

Commonly used propagation methods include: budding, high-altitude layering and cutting.

5.1 Bud grafting method: The rootstocks can be seedlings of peach, plum, plum, apricot, mountain peach, mountain apricot, hairy peach and purple-leaf plum. In comparison, peach stock has strong growth and purple-green leaves. , but are afraid of waterlogging; plum is more resistant to waterlogging as rootstock; apricot and plum have longer life span, but they are also afraid of waterlogging. In central Shandong, apricot, mountain peach and peach are the most commonly used rootstocks.

The rootstocks for grafting are generally 1-2 year old seedlings. It is best to be specially cultivated for rootstocks. They should be shortened before grafting, leaving only the 5-7cm stump on the ground. In mid-to-late June , determine the bud positions on the branches selected as scions in advance. The grafted buds should be plump, strong, and free of dry tips and diseases and insect pests. Use a sterilized bud grafting knife to cut upward into the xylem at a 30° angle 2cm below the bud until it reaches 1cm above the bud, then make a crosswise cut 1cm above the bud, gently remove the grafted bud, and then cut it 3cm above the rootstock. Use a knife to cut a "T"-shaped incision in the bark to tightly combine the grafting bud and the rootstock, and then tie it with a plastic strip. After grafting, if the grafted buds do not wilt for about 7 days, it means they have survived. The plastic strips can be removed in about 25 days.

5.2 High-altitude layering method: The branches should be selected from plants with strong tree vigor and free of diseases and insect pests. The diameter of the branches is generally 1-2cm, and 2-4 year old branches are the best. Layering is carried out from mid-April to mid-May in spring. Select a suitable part of the layering to score two notches with a grafting knife. The distance is about 1.5cm. Then girdle the epidermis between the notches. Immediately after the girdling Put on a plastic bag and tie it tightly at the bottom of the notch, then put the prepared sandy loam mud into the plastic bag and shape it into a ball. The mud ball should wrap the girdling area and keep it in the middle of the mud ball. , and then tie the top of the plastic bag shut. After sealing the plastic bag, check frequently to see if the mud ball is dry and hard. If the soil ball is soft, it means the wrapping effect is better and the soil moisture content is higher. The wound can heal and begin to take root in about 45 days. After the leaves fall in late autumn, cut the layering strip at the bottom of the mud ball, cut the plastic bag and transplant it. If it is dry and hard, it means there is air leakage in the plastic bag. Immediately inject water with a syringe and put another plastic bag outside the original plastic bag.

5.3 Cutting method: There are hard branch cuttings and twig cuttings.

5.3.1 Hard branch cuttings: Cuttings can be carried out from mid-to-late October to early to mid-November, but the cuttings need to be completed before the soil freezes. The seedbed should be set up in a sun shed with straw thatch or insulation quilt. The seedbed should be prepared half a month before cutting. Generally, it can be made into a flat bed. The soil should be sandy loam. Before making the bed, decomposed and fermented cow and horse manure should be applied. The dosage is 2600-800kg per 667m. The soil and fertilizer should be mixed well. After raking, mix 40% pentachloronitrobenzene particles with the soil thoroughly for disinfection. The dosage is 7-8g/m2. After disinfection, cover with plastic sheet and seal. The cutting branches should be free of diseases and insect pests, with a diameter of 0.5-1cm, and a high degree of lignification. The cuttings are generally cut to 12-15cm, and the lower cut is cut into a horseshoe shape. The upper cut should be smooth, 1-1.5cm away from the buds. Tie 100-150 roots into a bundle, soak in 500mg/kg IBA solution for 24 hours, and then take them out for later use. Before cutting, use a bamboo skewer to punch holes in the seedbed. The spacing between rows is 10cm × 10cm. Cutting is done after punching. The cutting depth is enough to expose 3-4 buds. Water thoroughly immediately after cutting. After cutting, the temperature in the shed should not be lower than 5°C. On sunny days, the insulation quilt or grass thatch should be uncovered around 9:30 am to increase the temperature and light, and the covering should be put down after 4:00 pm for heat preservation. Water thoroughly again in mid-March, and ventilate appropriately for seedling hardening at noon when the greenhouse temperature is high. In mid-April, remove the greenhouse film and spray 0.3% urea solution once on the leaves to enhance growth. After that, spray nitrogen, phosphorus and potassium compound fertilizer once every 10 days or so, and water according to the soil moisture. Keep the soil in a semi-dry and semi-moist state. Stop fertilizing before the end of August. In the spring of the second year, you can transplant it into the nursery for cultivation.

5.3.2 Young branch cuttings: Cuttings require a shade shed with a height of 1.8-2.0m. The sides and top of the shade shed are covered with a single layer of reed curtains, with a light transmittance of about 30%. Dig a low bed under the shade shed, 15-20cm deep and 1m wide. Fill the bed with clean river sand. The cuttings should be selected from mother trees that are healthy and free of diseases and insect pests, and the semi-lignified branches of the current year should be taken. Strips can be harvested in June, July and August in central Shandong. To prevent the cuttings from losing water, they should be cut as often as possible. The cuttings are 12-15cm long, leave 4-5 leaves on the top and remove the rest. The lower incision is smoothed with a single-sided blade. The cuttings treated with IBA500mg/kg solution had the best rooting performance, with a rooting rate of 95%. Before cutting, spray the seedbed with water, and then spray the bed surface with 4g/m2 carbendazim solution to start cutting. Dip the lower 2-3cm of the cuttings into the medicinal solution for 4-5 seconds. The depth of the cuttings is about 3cm, and the spacing between the rows is 5cm x 8cm. After the cuttings are inserted, spray water appropriately, set up a small plastic shed, and cover the plastic film tightly. After cutting and before taking root, spray water 1-2 times a day. For the convenience of water spraying, a plastic nozzle with a nozzle can be installed. Each time the water is sprayed for 30-45 seconds, the time is 11:00 am and 2:00 pm. To prevent cuttings from rotting, spray 0.1% carbendazim solution once every 7-10 days, preferably 2-3 times.