Detailed Explanation of the Cultivation Technical Specification for Golden Privet

Golden privet (Ligustrum vicaryi) is a semi-evergreen or deciduous small shrub of the genus Ligustrum in the family Oleaceae. With its golden-yellow color, it is widely used in urban and rural landscaping in China. To improve seedling quality and the landscape effect of garden cultivation, the author of this article led the compilation of a local standard, the Cultivation Technical Specification for Golden Privet in the Tianjin region. The main technical points are excerpted as follows.

1 Site conditions

Good drainage and irrigation conditions, flat and open, various types of sandy loam and loam rich in organic matter, pH range between 6.5 and 8.5, total salt content below 0.3%. For garden cultivation, an environment with good sunlight should be selected. Irrigation water quality: pH 5.5 to 8.0, mineralization degree not greater than 2500 mg/L.

2 Seedling propagation

2.1 Preparation of the cutting bed

Spread a 15-20 cm thick mixed substrate in the seedbed. The substrate volume ratio is: 30% garden soil, 60% river sand or other neutral loose substrate, and 10% decomposed organic fertilizer. 24 h before cutting, spray the surface of the seedbed with 0.5% potassium permanganate solution or other fungicide, then water appropriately.

2.2 Cutting period

Softwood cuttings from June to August; hardwood cuttings from mid-October to early November.

2.2 Cutting of cuttings and rooting hormone treatment. Each cutting should have 5-7 pairs of plump buds. Remove the leaves on the lower 1/3 to 1/2 of the cutting, keep 2-4 pairs of leaves on the upper part, cut flat about 1-2 cm above the first retained bud at the top, and cut at a 45 degree angle at the last bud at the bottom of the cutting; the cut must be smooth. Soak the base of the cutting in a rooting hormone solution. The treatment time is determined according to the variety of rooting hormone and the solution concentration.

2.4 Cutting

For hardwood cuttings, the plant and row spacing is 3 cm x 3 cm; for softwood cuttings, the plant and row spacing is 5 cm x 5 cm, with a depth of 3-5 cm, and water thoroughly after insertion. A plastic arch shed must be built on the bed surface to retain moisture.

2.5 Management after cutting

Softwood cuttings: in the initial stage, the humidity inside the arch shed should be above 95%, and the temperature should be 22-28 degrees C. Spray water twice daily around noon at intervals of 2-3 h to keep the cuttings and substrate moist. If the temperature inside the shed exceeds 28 degrees C, cool it down promptly. Spray the cuttings in the seedbed with 50% carbendazim WP and other fungicides every 6-7 d; see Table 1 for the application technique. 14-21 d after cutting, gradually adjust the humidity inside the shed to 70%-80%.

Hardwood cuttings: check the moisture of the seedbed inside the shed every 10-15 d, and water promptly if there is a water shortage. After the cuttings sprout and unfold leaves, prevent and control diseases; see Table 1 for the control technique. Do a good job of winter cold protection; in early spring, prevent damage to seedlings from high temperatures.

Hardening off: 14-21 d after softwood cutting, when most cuttings have rooted, ventilate appropriately every day to harden the seedlings. Ventilation time and light intensity should be gradually increased, and the plastic shed film and shade net should be gradually removed. Control watering 10-15 d before transplanting. For hardwood cutting seedbeds, ventilate to harden the seedlings 20-25 d before transplanting. Specifications of cutting seedlings: seedling height over 10 cm, more than 10 roots, length 5-10 cm.

2.6 Transplanting

For hardwood cuttings, the first transplanting is carried out in late April to early May of the second year; for softwood cuttings, it is carried out 50-60 d after cutting. Transplanting plant and row spacing is 30 cm x (20-25) cm; to cultivate large seedlings, a second transplanting should be carried out, with a plant and row spacing of 60 cm x 40 cm.

2.7 Management after transplanting

After transplanting in the same year, water thoroughly in time, and water a second time after 3-5 d. Water a third time after 7-10 d. Cultivate and weed in a timely manner. From May to August, carry out moderate pruning 3-5 times. See Table 1 for chemical control techniques for common diseases and insect pests. In early November, build heat preservation facilities, and from late November to early December, water thoroughly with frozen water. Management in the second and third years after transplanting: water thoroughly with green-up water in mid-March, and clean up fallen leaves and debris in the nursery in mid-to-late April. In September, apply (nitrogen-phosphorus-potassium 15-15-15) compound fertilizer, 30-40 kg/667 sq m, spread in furrows and then cover with soil, and water promptly. In mid-November, build arch sheds and other cold protection facilities. Other management is the same as specified in 5.3.

3 Leaving the nursery

3.1 Quality of nursery-exit seedlings

Comply with the requirements of CJ/T24-1999.

3.2 Lifting and packaging of seedlings

When lifting seedlings in the planting season, an appropriate amount of protective core soil should be retained and packaging should be included. In non-planting seasons, a soil ball must be included; when the soil ball diameter is less than 50 cm, it must be packaged with materials. The soil ball diameter is determined according to the standard of 0.26 to 0.33 times the seedling height.

3.3 Seedling labeling, transportation and quarantine

A quarantine certificate and label plate should be included, indicating the seedling name, seedling age, lifting date, quantity, plant quarantine certificate number, and issuing unit, etc. When loading, handle gently and place in layers. During transportation, moisture-retention and sun protection measures should be taken for the seedlings.

4 Garden cultivation

4.1 Requirements for greening sites

Should comply with the requirements of Chapter 1 of this article.

4.2 Point setting and line laying

Execute according to the provisions of 5.0.2 in DB29-68-2004.

4.3 Digging of planting holes (trenches) and fertilization

Should be executed according to the provisions of 5.0.3 to 5.0.5 in DB29-68-2004.

4.4 Planting density

Plant and row spacing (25-30) cm x (35-40) cm.

4.5 Planting

When planting bare-root seedlings, the root system must be spread out, and the soil should be filled in layers and firmed. The planting depth should be level with the original root collar soil line.

4.6 Management during the seedling recovery period

After planting, cut off the young branches and leaves at the top of the seedlings, water thoroughly in time, water a second time after 3-5 d, and water a third time after 7-10 d. In high-temperature seasons, cover with a shade net and remove it after the seedlings recover. During the seedling recovery period, spray the seedlings appropriately every day.

5 Maintenance and management

5.1 Water and fertilizer management

30-40 d after seedling recovery, apply nitrogen fertilizer such as urea 1-2 times along with watering, at an interval of 25-30 d, (20-25) kg/667 sq m. After heavy rainfall, drain accumulated water promptly; in autumn, reduce the amount and frequency of watering. In late March and early July each year, apply high-quality compound fertilizer with a nitrogen, phosphorus and potassium content of 45% (15-15-15) twice, at an application rate of 30-35 kg/667 sq m, and irrigate promptly after furrow application.

5.2 Pruning

Prune and shape according to the requirements of the garden landscape design, 3-5 times each year.

5.3 Cultivation and weeding

Cultivate and weed in a timely manner, with a depth of 3-5 cm; remove weeds and transport them away promptly.

5.4 Disease and insect pest control

5.5 Overwintering and cold protection

In winter, heat preservation measures must be taken for cold protection, and frozen water should be watered thoroughly from late November to early December.