Korla Fragrant Pear Open-Center Training Technique and Cultivation Key Points

In order to continuously raise the level of orchard industry development, the "dwarf, dense, early, high-yield" cultivation technique should be adhered to in fragrant pear orchard management, and management should follow the six-character policy of "slow, drop, control, promote, cut, even."

1. Conditions and methods for open-center reshaping

1. Fragrant pear trees over 25 years old are basically the traditional three-main-branch delayed open-center form, and the tree form has already set. If the tree form is complete, the three or four main branches at the base are sound, and the canopy has already filled the space, the central leader can be directly dropped for open-center; if the lower main branches are incomplete, with only 1-2 main branches, and there are very good large interlayer branches, the double-layer trunk form can be used; if there are only 1-2 main branches at the base, no space for large branches, and the crown is obviously lopsided, open-center is not suitable.

2. For trees directly opened to open-center, remove the central leader 5-10 cm above the selected 3rd or 4th main branch, so the tree body takes a single-layer structure with a tree height of 2.5-3 m. When sawing, cut the branches in layers from top to bottom, keep the saw cut smooth with a stub, and after sawing apply disinfectant and protectant. For fruit trees using the double-layer trunk form, remove the central leader 5-10 cm above the 2nd layer of main branches, keep the tree height within 3.5 m, and ensure distinct structural layers, with the base main branch angle at 60°-70°, the 2nd-layer main branch angle above 80°, and the interlayer spacing above 1.2 m.

3. After reshaping, the tree height should be controlled within 3 m, with 3-4 permanent main branches, the main branch base angle kept at 60°-75°, and 6-8 lateral branches. The main and lateral branches should be equipped with a number of reasonably arranged large and medium fruiting branch groups; large fruiting branch groups in the middle of the main branch, medium and small fruiting branch groups at the base of the main branch, small and medium branch groups borne on the upper back, medium branch groups borne on the lower back, and large branch groups borne laterally, ultimately forming 70% short fruiting branches, 15% medium fruiting branches, and 15% long fruiting branches.

4. The best time for reshaping is from mid-November to mid-February of the following year.

2. Pruning after reshaping

1. Pruning methods

First, when propping and pulling the main branch angle, because there is no central leader, the main branch angle only needs to reach 50°-60°. The several main branches can be adjusted by regulating the base angle, waist angle, and tip angle so that the tips of the main branches are on the same horizontal plane.

Second, the extension direction of each main branch should be made clear. If there is space, heading back can be used to promote development and the fruiting branch can continue to extend; if there is no space, appropriate renewal pruning can be used to maintain a certain ventilation zone; if the main branch extension head is too strong or too weak, it should be cut back and the leader changed. With both extension and retraction, balanced growth should always be maintained.

Third, clean up and cultivate all types of branch groups. Use slow release for strong branches and medium-long branches, and combine weak branch promotion with group formation to cultivate reasonable branch groups. Use all kinds of branches as much as possible, adopting heading back, slow release, and renewal pruning, combined with summer pinching, to cultivate large, medium, and small fruiting branch groups, so that branch group arrangement combines long and short and is well staggered. Remove crossing branches, crowded branches, and dead branches; cut back drooping branches and thin, weak, elongated branches, maintaining balanced tree vigor, clean layers, and even light.

2. Summer pruning

① After open-center training, a large number of latent buds sprout on the upper side of each main branch at the saw cuts, producing new shoots and consuming nutrients. In mid-to-late April, promptly select and retain branches that fill empty spaces, remove excess sprouts, reduce nutrient consumption, and promote flower bud differentiation and formation for the coming year.

② Summer pinching is an important means of promoting branch maturity and flower bud formation. For new shoots sent out from fruit tree branches, pinching can be done when they reach more than 20 cm in length. For newly grown fruit spurs and secondary shoots, remove the weak and retain the strong, remove the upright and retain the slanted, and pinch when over 15 cm to promote the formation of axillary flower buds.

3. Fertilizer and water management

1. Base fertilizer

Apply fully decomposed high-quality base fertilizer after fruit harvest and before the soil freezes, no less than 100 kg per 667 sq m, and apply phosphorus and potassium fertilizer at the same time.

2. Topdressing

The 1st topdressing is 2 weeks before bud break in early spring, mainly nitrogen fertilizer; the 2nd topdressing is from mid-May to early June, preferably a nitrogen, phosphorus, and potassium compound fertilizer; the 3rd topdressing is in July-August, mainly nitrogen and potassium fertilizer, 50 kg per 667 sq m, which can increase single fruit weight and improve quality. Under general soil fertility levels, the total chemical fertilizer input per ton of fruit per 667 sq m is 80 kg, with a nitrogen, phosphorus, and potassium ratio of 1:0.5:1. For foliar topdressing, spray more than 5 times throughout the year, using foliar fertilizer at full bloom, flower bud differentiation, fruit enlargement, and before and after harvest. The foliar fertilizer is 0.3%-0.5% urea and 0.3%-0.5% potassium dihydrogen phosphate. Fertilization is mainly by spot application, hole application, and ring trench application, at a depth of 20 cm.

3. Irrigation

Irrigate 8-9 times throughout the year; irrigate once each month from March to May, and once every 20 days during the high-temperature season from June to August. Pay attention to water control in mid-May to promote flower bud differentiation. After September, control water in a balanced way, and irrigate winter water well in October-November.

4. Pest and disease control

The main pests and diseases of fragrant pear in the Korla area are: fragrant pear fruit borer, pear psylla, spider mites, codling moth, pear tree canker, etc. The main measures of agricultural control include cleaning the orchard, picking infested fruits, scraping tree bark, banding the trunk with film and grass, and deep plowing and leveling the land. Biological control mainly involves the application of various pheromones. Chemical control mainly involves establishing a pest forecasting system and conducting timely chemical control according to chemical control thresholds. Adopt spot, patch, band, and individual tree control methods to eliminate pest sources, use pesticides with high efficiency, low toxicity, low residue, and strong selectivity, avoid broad-spectrum pesticides, and alternate their use to avoid resistance.