Detailed Explanation of the Key Cultivation and Management Techniques for the Black Locust (Robinia pseudoacacia 'Idaho')

I. Propagation Methods

The black locust is easy to propagate by root burying, cuttings, or grafting, and can also be propagated by digging up roots. For root burying propagation, select 1-2 year old main and lateral roots of the black locust, with a diameter of 0.3-1.5 cm being suitable. Each mu requires 10-12 kg of seed roots, and each kg of seed roots can be cut into 300-400 segments. Two methods can be used: greenhouse seedling raising and transplanting, and field root burying. The seedling raising time indoors varies depending on the region, and transplanting to the field is done in mid-May. Field root burying is carried out when the outdoor minimum temperature is above 10°C. Cut the black locust roots into segments 5-6 cm long, and bury the roots in the seedbed using the flat burying method. For a bed 1.1 m wide, plant 2 rows per bed, with a burial depth of about 5 cm, and a plant-row spacing of 30 cm × 60 cm. After emergence, strengthen water and fertilizer management. Use diammonium phosphate with potassium fertilizer as base fertilizer, at a ratio of 2:1, with a application rate of 15-20 kg per mu.

Root digging: one method is to dig around the tree without moving it; another method is to dig out the tree together with its roots, leaving 15-20 cm of the roots, and cutting off the rest with scissors for storage. After the roots are dug out, they must be stored immediately, and dug up as they are sold, to prevent air-drying and dehydration. Choose a sandy loam soil in a wind-sheltered, light-avoiding area with a soil layer 1.8-2 m thick, and with good drainage and no water accumulation, to dig a pit. Mix the seed roots evenly with fine sand and bury them. The fine sand should be pre-sieved to remove stones, and maintain a certain humidity, but the moisture must not be excessive. After all are buried, add 20-30 cm of fine sandy soil on the top layer for cold protection. If there is unusually cold weather, a layer of straw curtain can be added, and at the same time, prevent overheating. The biggest problem in storage is that it must not heat up and become moldy.

The black locust is easy to raise seedlings, and the planting survival rate is high. The survival rate of planted seedlings is about 95%, the survival rate of seed roots is over 80%, and the survival rate of cuttings is relatively low, but can reach 40% with proper cultivation.

II. Seedling Cultivation and Management

Plant-row spacing 60 cm × 70 cm, plant 1000 seedlings per mu. Transplanting of the black locust is best done after leaf fall in autumn or before sprouting in spring. Determine the planting time according to regional temperature conditions. Planting can be carried out when the minimum spring temperature is 10°C, and transplanting can also be done after the frost's descent in autumn. For transplanting 1-2 year old seedlings, dig holes 40 cm in length, width, and depth, and increase appropriately for larger seedlings. Apply base fertilizer at the bottom of the hole using diammonium phosphate with potassium fertilizer, at a ratio of 2:1. Isolate with a soil layer of 15-20 cm. Place the sapling in, fill with water, and after the water seeps down, fill with soil and compact. In arid areas, water timely to keep the soil moist.

Before the seedling grows to 3 cm, remove the lateral buds to ensure rapid growth of the main trunk. When the main trunk reaches 1.8 m, start retaining lateral branches. When the main trunk grows to 2.5 m, remove the main trunk's growing tip to set the trunk height, to meet the needs of landscaping street trees. Fertilize and weed timely, and prevent the occurrence of pests and diseases.