Key Points of Early High-Yield Cultivation Techniques for Peach Trees
In the spring of 2002, a peach orchard of 0.67 hm2 was established in Yutian County, Tangshan City, with the cultivars Shijiwang Tao and Shijihong Tao. In 2003, the average yield per 667 m2 was 890 kg; in 2004 it reached 2400 kg; and in 2005, 2006, and 2007 the yield stabilized at 3500 kg. The specific management techniques are described below.
1 Orchard Establishment
1.1 Site Selection. Select a plot with loose soil, high and dry terrain, good drainage, ample sunlight, convenient transportation, and suitability for peach production.
1.2 Site Preparation. Land was prepared before the winter of 2001. Planting trenches were dug at a row spacing of 4 m, with a trench width of 100 cm and a depth of 80 cm. Topsoil and subsoil were placed separately on either side of the trench. When backfilling, part of the topsoil, basal fertilizer, and subsoil were first mixed and filled in, applying 5000 kg of high-quality barnyard manure per 667 m2 as basal fertilizer. Then a layer of soil was covered, and the remaining soil was piled on both sides of the trench to form ridges, after which the planting trench was irrigated.
1.3 Planting Density and Method. Hole spacing was 1.4 m, row spacing 4 m, with two plants per hole. A total of 238 plants were planted per 667 m2.
1.4 Planting. Planting began around March 20, 2002, using 1-year-old large seedlings. Before planting, the seedlings were graded, their root systems pruned, then soaked in clean water for 12-24 h, and their roots dipped in a 1% copper sulfate solution for 5 min to prevent crown gall disease. At the same time, planting holes 50 cm wide and 50 cm deep were dug according to the hole spacing, with two plants per hole. The two seedlings in the same hole were required to be similar in size and growth vigor, and the root crown of the seedlings had to be slightly above ground level to prevent the seedlings from sinking after irrigation and being planted too deep. After planting, one thorough watering was given, and on the 2nd day a 1 m wide plastic film was laid over the planting trench. During the seedling recovery period, irrigation was carried out according to soil moisture conditions.
2 First-Year Cultivation Management
2.1 Training and Pruning
2.1.1 Growing-Season Pruning. After planting, the seedlings were not headed back; thin and weak secondary branches were removed, and thick and strong secondary branches were cut back leaving 2-3 buds. After the seedlings sprouted, branches were evenly retained around each seedling, with the distance between branches on the same side at 20-25 cm and one branch retained per bud position, so that the entire seedling grew upright. When new shoots grew to 20-40 cm, they were repeatedly pinched to increase branching orders and promote early canopy formation. By mid-to-late June, stem bending was started, pulling the two peach trees in the same hole toward two different inter-row spaces. The trunk height was required to be 50-60 cm, with a bending angle of about 70°, and no arching was allowed. After bending the branches, branch selection was carried out. One branch was retained every 20-25 cm on both sides, with fewer branches retained on the upper and lower sides of the limb. For upright branches, the principle was to remove them if there was no space and keep them if there was space; retained branches were softened by bending to open the angle, ease branch vigor, and promote flower bud formation. In mid-to-late August, all new shoots that had not stopped growing were pinched to promote thickening growth and flower bud differentiation, making the branches and buds plump and facilitating safe overwintering.
2.1.2 Winter Pruning. Long-branch pruning was adopted. It can control excessive tree growth, reduce the number of pruning operations, promote early fruiting, early high yield, and stable production, and improve fruit quality. Branch renewal is easy, and it can prevent the inner canopy from becoming bare. Long-branch pruning is a technique that basically does not use heading cuts and only uses thinning and long retention. During pruning, excessively vigorous branches, thin and weak branches, diseased and pest-infested branches, crossing branches, and overlapping branches were removed. One-year-old fruiting branches 40-60 cm long were retained. The number of fruiting branches retained was preferably about 20 per tree, distributed evenly on the peach tree, with vegetative branches no fewer than fruiting branches. A 0.5 m light path should be left between rows to facilitate orchard management and ventilation and light penetration. After 1 year of management, the main branches basically reached the required size.
2.2 Soil, Fertilizer, and Water Management. In terms of soil management, timely cultivation and weeding were carried out to create a good soil environment for peach tree growth. In terms of fertilizer and water management, attention was paid to promoting early and controlling later. From after planting to late June, fertilizer and water management were strengthened. Before and after sprouting, a quick-acting fertilizer mainly based on nitrogen fertilizer, such as urea or ammonium sulfate, was applied along with watering to promote new shoot growth and accelerate canopy formation. After late June, fertilizer and water were controlled, and pruning techniques were used to promote the transition from vegetative growth to reproductive growth and the formation of numerous good flower buds. Peach trees have shallow roots and are not tolerant of waterlogging, so drainage was attended to during the rainy season. In September-October, 5000 kg of barnyard manure was applied per 667 m2. Before the soil froze, winter irrigation was given.
3 Cultivation Management in the Second Year and Beyond
3.1 Training and Pruning
3.1.1 Growing-Season Pruning. The focus was on bud removal, shoot thinning, and pinching. In spring, when new shoots grew to 3-5 cm, clustered new shoots at pruning and saw cuts and useless new shoots below the trunk were removed. Overly dense shoots and water sprouts were thinned to improve ventilation and light conditions. For some upright branches that were retained, twisting and bending were used to change the growth direction of the shoots. Pinching was carried out in 3 rounds: the 1st in late May, aimed at promoting the sprouting of secondary shoots to form good branches; all new shoots longer than 10 cm were pinched while retaining 10 cm. The 2nd pinching was in late June to early July, aimed at promoting the filling out of new shoots and secondary shoots, plump axillary buds, and flower bud differentiation; all branches longer than 30 cm were pinched. The 3rd was generally in late August to early September, when the tender tips of all branches could be pinched off to promote thickening growth of shoots, make branches and buds plump, and facilitate safe overwintering.
3.1.2 Winter Pruning. Long-branch pruning was still adopted, with the same pruning method as in the first year, but the cultivation and renewal of fruiting branch groups were strengthened. In combination with summer pruning, within 2-3 years, 2 stable medium-to-large fruiting branch groups were cultivated on each side of the middle and rear parts of each tree, and an appropriate number of small branch groups were arranged between the upper part of the main branches and the large and medium fruiting branch groups to achieve the goal of three-dimensional fruiting. During winter pruning, the fruiting mother branches that had already borne fruit were retracted to good basal branching points to prevent the fruiting zone from moving outward.
3.2 Flower and Fruit Thinning. Peach trees produce a large number of flowers. If flower and fruit thinning are not carried out, not only is a large amount of nutrients consumed, but the fruit is also small and of poor quality. Therefore, reasonable flower and fruit thinning is one of the important measures for stable, high, and high-quality yields in peach trees. From the perspective of saving nutrients, the earlier the thinning, the better. Therefore, it was carried out in 3 steps: first, pre-bloom follow-up pruning was the main measure, cutting out leafless flowering branches; second, during the flowering period, early flowers, late flowers, and deformed flowers were thinned; third, fruit thinning was generally carried out 20-25 d after flowering and could be completed in one operation. According to practical experience, the fruit retention standard was: 2 fruits on vigorous fruiting branches, 1-2 fruits on long fruiting branches, 1 fruit on medium fruiting branches, and no fruit on short fruiting branches and bouquet fruiting branches. More fruits were retained on the outer and upper parts of the canopy, and fewer on the inner and lower parts. Fruit retention could also be determined by the leaf-to-fruit ratio, with about 50 leaves retaining 1 fruit.
3.3 Soil, Fertilizer, and Water Management. One year after planting, the peach trees began to bear fruit. Soil management was mainly cultivation and weeding. Topdressing was carried out in the following 3 periods: the 1st before and after sprouting, applying fertilizer mainly based on quick-acting nitrogen fertilizer, in an amount that should not be too large, otherwise it easily causes excessive growth. The 2nd 20 d before fruit harvest, applying fertilizer mainly based on potassium fertilizer, supplemented with a small amount of nitrogen and phosphorus fertilizer. This fertilizer was the fruit-strengthening fertilizer and the most critical fertilization of the year for peach trees. The 3rd after fruit harvest, applying a nitrogen-based nitrogen, phosphorus, and potassium compound fertilizer once. This topdressing could be combined with early application of basal fertilizer, generally applied in trenches dug between peach tree rows. Irrigation was generally carried out during the sprouting period, from after flowering to before pit hardening, and during the fruit enlargement period. Peach trees should be irrigated frequently, but the amount of water each time should be small. In addition, 1 winter irrigation was given from late October to early November.
4 Pest and Disease Control
The main pests and diseases on peach trees are aphids, red spider mites, leaf miners, and peach shot hole disease. In combination with winter pruning, diseased and pest-infested branches were cut off and fallen leaves swept up and burned in a concentrated manner. Before sprouting, in combination with the control of other pests and diseases, 3°-5°Be lime sulfur mixture was sprayed to kill overwintering eggs and overwintering pathogens. In mid-May, 1000-fold fenvalerate solution could be used to control aphids. With 1500-fold propargite solution, 1000-fold saomanjing solution, and 1000-fold pyridaben solution, red spider mites could be controlled. In mid-July, 600-fold chongshashuang solution and 2000-fold diflubenzuron No. 3 solution could prevent leaf miners. With 70% thiophanate-methyl 1000-fold solution and 70% mancozeb 800-fold solution, peach shot hole disease could be controlled.