Cultivation Techniques for American Blackberry in Xinjiang

Blackberry, a plant of the genus Rubus in the Rosaceae family, is mainly distributed in China in the valley shrublands and forest margins on the northern slope of the Tianshan Mountains in Xinjiang, with a greater distribution in the Ili region. The blackberry fruit is an aggregate drupe, with a rich fragrance and abundant nutritional and health benefits. The World Health Organization has listed it as a third-generation health food. It is widely cultivated in some European and American countries. In the United States, it is mainly distributed in 4 regions including California along the northwestern Pacific coast, and each region has its own suitable main cultivars. The factors determining the range of variety adaptation include cold resistance, drought resistance, temperature requirements, sensitivity to pests and diseases, and adaptability to various soils. To explore the adaptability of blackberry in Xinjiang, we conducted blackberry introduction and cultivation trials and systematic observations in 1999, aiming to provide a scientific basis for the large-scale promotion of blackberry in Xinjiang.

1. Basic conditions of the trial site. In the experimental field at the headquarters of the Gongliu Forest Farm in Xinjiang, the local altitude is 1200-1400 m, located right in the temperature inversion layer of the western Tianshan Mountains. Therefore, compared with other areas of Xinjiang, it has more abundant rainfall and a milder, more humid climate. The annual average temperature is 5-7°C, the average January temperature is -8°C; the average July temperature is 18°C; the annual accumulated temperature above 10°C is 2200°C-2900°C. The annual average precipitation is 600-800 mm, with some years exceeding 1000 mm, and 60% of the annual precipitation is concentrated in the plant growing season. The annual average evaporation is 1100-1200 mm. The annual average relative humidity is above 70%, and the climate aridity is less than 4; the frost-free period is 120 days. The first frost is generally in early September, and the last frost in mid-May. The first snow and the last snow are respectively in early October and early May. The soil freezes in early November and thaws in late March. The soil is mountain chernozem, with a pH of 6.8-7.5, and irrigation conditions are available, with the irrigation water being meltwater from Tianshan snow.

2. Introduction performance. Phenological period - At the Gongliu Forest Farm, both blackberry varieties sprout and unfold leaves in mid-April, form buds in late May, bloom in early June, with the flowering period lasting until mid-July, and the entire flowering period is 40-45 days; the fruit begins to ripen successively in mid-to-late July, with the concentrated ripening period in early August, and leaf fall begins in mid-September. Plant growth performance - Except for the current-year branches that do not bear fruit, all plants bore fruit in 2001, with an average yield per plant of more than 5.5 kg, a maximum yield per plant of 7.8 kg, an average single fruit weight of more than 10.5 jin, and a maximum single fruit weight of 15.5 jin, equivalent to a yield of more than 850 kg per 666.7 sq m. The fruit is conical, relatively large, black-purple when ripe, crystal clear, soft in texture and juicy, sweet and sour and palatable, with a rich fragrance. The seeds are only slightly larger than sesame seeds. It shows good growth, strong adaptability, tolerance to barren soil, tolerance to extensive management, and low requirements for fertilizer and water conditions. It is cold-resistant and moisture-resistant, and has very strong adaptability when planted in moist low-lying land; at the same time, it is also relatively drought-resistant, and growth and fruiting are not affected when it is not watered for many days; it propagates easily, and cutting and root sucker propagation have extremely high survival rates and seedling formation rates, with vigorous growth. If allowed to grow freely, its new shoots can reach more than 5 m in length, and its branching ability is also extremely strong. Generally, when planted in the same year, it can take shape in the same year through multiple pinching; pest and disease damage is light, and in nearly 8 years of trial planting, no serious lethal pests or diseases have been found.

3. Key points of cultivation techniques. Site selection and seedling raising - The orchard site should preferably be sunny and sheltered from the wind, with sufficient light, convenient drainage and irrigation, and loose sandy loam soil. After the orchard site is prepared, organic fertilizer should preferably be applied in autumn as base fertilizer, with 1000-1500 kg of fully decomposed farmyard manure per 666.7 sq m plus 50 kg of urea and phosphate fertilizer. For seedling raising, cutting propagation is relatively commonly used, and hardwood cuttings under full-light mist propagation can also be used. In autumn, select one- to two-year-old branches and cut them into 15-20 cm cuttings, with the lower end cut obliquely below a node and the upper end cut flat 0.5 cm above a node. Tie 30 branches into a bundle, soak the lower ends in a solution of 100 mg ABT rooting powder per liter of water for 1 hour, then store them in sand for use the following spring; alternatively, during the Spring Festival, select mature and robust branches grown in the previous year and cut them into 10-10 cm cuttings, treat them with ABT rooting powder solution, and then insert them. When inserting, generally leave 1-2 buds above the ground. Planting and fertilizer and water management - The plant and row spacing of blackberry is generally 2 m × 2 m, with 170 plants planted per 666.7 sq m. The planting holes are 60 cm in length, width, and height, and base fertilizer is applied in each hole. Planting can be done either in autumn before the soil freezes or in spring after the soil thaws and before sprouting, but autumn planting is better. When planting, spread out the root system, water thoroughly, and pay attention to watering for drought resistance in the early stage of planting. Topdressing should be carried out at the initial flowering stage and after fruit set, mainly with nitrogen fertilizer in the early stage, and combined with phosphorus and potassium fertilizer in the later stage. Blackberry likes moisture but is not tolerant of waterlogging, so in the rainy season, low-lying areas should be drained in time. Generally, watering is combined with topdressing after sprouting, after flowering and fruit set, during the fruit enlargement period, and before freezing. When entering the fruiting period, it is necessary to ensure water before flowering, water after flowering, and water for fruit enlargement. After watering, the soil should be loosened immediately to preserve moisture, and intertillage and weeding should be carried out at the same time. Trellising, pinching, and pruning - Newly planted seedlings tend to bend when they grow to 50 cm, so after planting, a trellis should be set up immediately for tying, with a trellis height of 1.8-2.0 m. A hedgerow trellis or trellis may be used. On the trellis surface, leave one new shoot every 30 cm without overlapping. Also pinch the new shoots to promote maturity and more branching. In the second spring, cut back the overwintered branches; thick and strong branches should be left longer, and weak ones should be left shorter. After flowering, based on the principle of removing the weak and retaining the strong, select the second-year fruiting branches, and cut off overly dense branches and pest- and disease-damaged branches, so as to increase the rapid growth of vegetative branches and improve the fruiting capacity of fruiting branches; after fruit harvesting is completed, lightly prune the branches that have already borne fruit close to the ground.

Pest and disease control - Common diseases of blackberry include leaf spot and leaf rust, generally occurring mostly between June and August, mainly damaging blackberry leaves. This stage is also exactly the period when blackberry fruits have just formed and are gradually ripening. Therefore, control should be carried out in early spring when blackberry begins to sprout. Control method: generally spray plants with a 1000-1500 times solution of 50% thiophanate-methyl wettable powder and a 2000-5000 solution of 15% triadimefon, which can provide good preventive and therapeutic effects. The main insect pests of blackberry are boring beetles, aphids, and stink bugs, but they occur relatively rarely, and can be controlled by spraying with a 1500-2000 times solution of 40% omethoate emulsifiable concentrate in April-May.