What practical techniques are there for high-yield cultivation of Sichuan pepper?
Sichuan pepper (scientific name: Zanthoxylum bungeanum Maxim.), also known as hui, da jiao, Qin pepper, Shu pepper, Chuan pepper or mountain pepper. It is a deciduous shrub or small tree of the genus Zanthoxylum in the family Rutaceae, and can be planted alone or used as a protective thorn hedge. Its fruit peel can be used as a seasoning, can also be used to extract aromatic oil, and can also be used as medicine; the seeds can be eaten and can also be processed into soap. Sichuan pepper is a deciduous shrub of the family Rutaceae, and its fruit peel, roots and seeds can all be used medicinally; it is also a commonly used condiment, and the leaves of Sichuan pepper can also be eaten. Sichuan pepper is a drought-tolerant, shallow-rooted plant with strong adaptability. In recent years, with the adjustment of the agricultural industrialization structure, the development of Sichuan pepper production has been combined with returning farmland to forest, greening barren hills and developing the rural economy, so that the cultivated area of Sichuan pepper has developed very rapidly in arid hilly areas. However, if cultivation and management are extensive, its yield and quality will be affected. Therefore, the following key links should be handled well in the cultivation and management of Sichuan pepper.
Seed collection
Select middle-aged trees with strong vigor, no pests or diseases, high yield and no alternate-year bearing as mother trees for seed collection, and pick by hand with scissors in August to September after the fruit is fully mature. After harvest, place the seeds in a ventilated and dry place to dry naturally in the shade; never expose them to strong sunlight, so as not to affect the germination rate. Collect after the fruit peel cracks and the seeds fall out on their own.
Raising seedlings
Sichuan pepper seeds have a hard seed coat and are rich in oil, which is not conducive to water absorption and germination, so germination must be promoted before sowing. Generally, soak them in 1% laundry detergent for 2 days, or soak them briefly in concentrated sulfuric acid, then remove them and rub them clean with clear water before sowing. For the breeding nursery, sandy soil or loam in a well-drained, wind-sheltered, sunny place is best. Sichuan pepper seeds are small and must not be sown deeply; generally 2 to 3 cm is enough. After sowing, cover with decomposed organic fertilizer and water once every 1 to 2 days to help preserve soil moisture, prevent crusting and improve the seedling emergence rate.
Planting out
Planting out can be done in both spring and autumn. Pits need to be dug for planting, and the size of the pits should be suitable for spreading out the root system. The soil put into the pits is best weathered and matured by wind and sun, then mixed with fertilizer and filled into the pits.
Fertilizer and water management
Sichuan pepper has a well-developed root system and a strong ability to conserve water and soil, so in arid areas there should be measures to preserve soil moisture, and supplementing with necessary base fertilizer and a small amount of foliar fertilizer can meet the fertilizer and water needs of Sichuan pepper. Generally, after autumn and during spring plowing, apply 1 application each of organic fertilizer such as barnyard manure or compost. The amount of fertilizer applied depends on tree age and fruit load, generally more than 20 kg per tree. Foliar topdressing starts from the flowering period, about once a month, sprayed in the early morning or evening, for a total of 2 to 3 sprays.
Shaping and pruning
Sichuan pepper trees like light and grow branches quickly. Therefore, reasonable shaping and pruning can make the tree framework firm, the branches robust, and achieve high and stable yields year after year. Pruning is best done in late autumn. During pruning, excess branches at the base can be removed, leaving 3 to 5 main branches, and shaping is completed after 4 to 5 years. Finally, remove the central branch and open up the center. Middle-aged trees should be carefully pruned, thinning out diseased, pest-infested, crossing and water-sprout branches within the crown so that the crown is ventilated and lets in light, thereby stabilizing tree vigor. When pruning about 25-year-old senescent trees, remove large branches, weak branches and diseased branches, and use water sprouts to alternately renew the tree framework to ensure a certain yield.
Pest and disease control
Brown spot disease Mainly harms Sichuan pepper leaves. At the beginning of the disease, pale yellow chlorotic spots appear on the leaf surface, then gradually expand into irregular large brown spots; the edges of the spots are darker in color, and small black dots can be seen on them. When the disease is severe, it can cause leaves to wither and fall off. For this disease, Bordeaux mixture, carbendazim and the like can be sprayed in the early stage of onset for control.
Dry rot disease Harms Sichuan pepper trunks and branches. In the early stage, the diseased part shows small reddish-brown spots, then the diseased part expands upward and downward, becomes sunken and exudes gum, which can cause large-area decay of the bark, yellowing of leaves and death of branches. Strengthening fertilizer and water management and pruning reasonably to enhance tree vigor can reduce the occurrence of this disease. After onset, use a sterilized knife to cut the bark to the xylem, and apply Bordeaux mixture or thiophanate-methyl to effectively prevent the spread of the lesions.
Aphids Often gather densely in large numbers on young shoots and leaves to suck sap and cause damage, affecting photosynthesis. This makes leaves turn yellow and curl, and in severe cases can cause premature leaf fall of Sichuan pepper. Phoxim, fenpropathrin and the like can be sprayed for control.
Sichuan pepper swallowtail Its larvae feed on buds, leaves and other young parts, and in severe cases can eat all the leaves of the whole plant. Manually removing overwintering pupae in winter and spring can reduce the pest population density the following year. When damage occurs, trichlorfon or dichlorvos can be sprayed for control.
Longhorn beetles The larvae overwinter in tunnels bored in the trunk. In the following spring, they bore under the bark into the xylem to cause damage, and discharge large amounts of reddish-brown frass and debris outside the bore holes, causing the trunk to become hollow and prone to wind breakage, decay, and even death of the whole plant. Adult longhorn beetles have the habit of resting quietly on branches at noon, so they can be shaken down and killed; larvae can also be hooked out and killed with wire, or aluminum phosphide (1/8 to 1/4 of a 0.6 g tablet) can be inserted into the bore hole and the opening sealed tightly with sticky mud for control; dichlorvos or trichlorfon can also be sprayed for control.
Preventing freezing injury Sichuan pepper trees have a shallow root distribution and are prone to freezing injury in winter and to the effects of a “late spring cold snap” in early spring. The following measures can be taken for protection: 1. For overwintering, plastic film and other coverings can be used for protection, or quicklime, sulfur, table salt and water can be mixed in a ratio of 10:1:4:40 and applied to the trunk; 2. Before the spring cold arrives, spray fruit tree antifreeze; also, on the night the spring cold arrives, pile dry grass, wheat bran and the like in the Sichuan pepper orchard and ignite them to produce smoke to form a smoke screen to improve the microclimate in the orchard and prevent flower buds from freezing injury.