What are the key points of comprehensive management during the dormant period of pear trees?

The dormant period of pear trees runs from after leaf fall to before bud break the following year. After leaf fall, a small amount of nutrients still flows back in the direction of small branches to large branches to trunk to root system, and accumulates and is stored in the root system. Before bud break in early spring, nutrients begin to flow from the underground part to the aboveground part along with the sap flow, in an order exactly opposite to that of the backflow. Compared with the growing season, tree activity during the dormant period is relatively weak, and the stored nutrients in the aboveground branches and trunk are relatively limited, making this period suitable for winter pruning. The following management techniques should be adopted during this period:

1. Be sure to promptly scrape off the thick, old, peeling bark on the trunk, main branches and other scaffold branches, and burn it in a centralized manner to eliminate pests overwriting in the bark cracks; thoroughly scrape and treat canker and ring rot lesions, and burn them immediately. Before winter, the tree should be whitewashed to improve its cold resistance.

2. In combination with winter pruning, thin out diseased and pest-infested branches, remove diseased and mummified fruit, sweep up fallen leaves and fruit, and spray the whole tree once with an eradicant.

3. In water-deficient orchards, when the soil thaws by day and freezes by night, irrigate the whole orchard once, which can eliminate a large number of overwintering pests and is very beneficial for the safe overwintering of fruit trees.

4. In winter, pear trees have no leaves and are in a dormant state, and most of the stored nutrients have already been transported to the root system and branches and trunk. At this time, pruning away useless branches can save a large amount of nutrients, which is beneficial to tree growth the following year and enhances tree vigor. The main tasks of winter pruning are shaping the canopy, adjusting branches and buds, renewing branch groups, rationalizing the relationships among various branches and trunk, fixing the growth angle and position of main branches, adjusting the size, density and structure of fruiting branch groups, dealing with irregular branches, and controlling the total branch volume and flower bud volume of the tree.

5. The flower buds of pear trees are relatively easy to identify. During winter pruning, for trees in an "on" year, flower thinning should be done ahead of time; for excessive flowering branches, break the terminal flower buds or moderately cut back according to the branch-to-fruit ratio to reduce the number of flower buds. For trees in an "off" year, all flowers should be retained and flower-blocking pruning should be carried out, which can reduce the consumption of stored nutrients in the tree. For vegetative branches, short pruning can be used to exchange branches for branches and reduce flower bud formation the following year. For weak trees with no flowers or few flowers, select and retain high-quality leaf buds and prune away excessive poor-quality leaf buds, which is beneficial for improving the quality of new shoots, enhancing photosynthetic efficiency and restoring tree vigor.