How to prune navel orange trees with alternate bearing? Detailed methods
1. Girdling to promote flowering: In mid-September of the following year, use a girdling tool to girdle upright vigorous branches, with a blade spacing of 0.3 cm. After girdling, apply Flower Promotion King No. 2 (southern variety), which can control shoots and promote flowering, and protect flowers and fruits. 2. Pre-flowering pruning: Winter pruning should be light or skipped, with the focus placed on pre-flowering pruning. High...
After navel orange trees enter the full fruit-bearing stage, if management is poor and nutrition cannot keep up, alternate bearing is likely to occur. Trees with alternate bearing and trees with high and stable yields require different pruning methods.1. Pruning of on-year trees: Pruning of on-year trees refers to the winter pruning, early spring pruning and summer pruning before the on-year fruiting. The following measures are usually taken: first, thin out dense weak branches, crossing branches and diseased and insect-damaged branches; second, cut back declining branch groups and branch groups that have dropped flowers and fruits; third, thin out the crowded large branches in the upper and middle parts of the canopy, so that light can enter the inner canopy; fourth, short-prune the mother branches of summer and autumn shoots. Because there are too many mother branches that can form flower buds in an on year, 1/3 of the weak mother branches can be thinned out, 1/3 of the strong mother branches can be short-pruned, and 1/3 of the moderate mother branches can be retained, so as to reduce the number of flowers and promote vegetative growth. Since the yield difference between on years and off years is very large, more short pruning can be done, fewer flowering mother branches can be retained, and flower thinning can be increased, so that the yield in an on year is relatively reduced and the yield in an off year is relatively increased; fifth, in July, short-prune some fruiting branch groups and branch groups that have dropped flowers and fruits, to promote autumn shoots and increase the fruiting mother branches for the off year; sixth, after the second physiological fruit drop stops, thin fruits in stages, and finally retain fruits according to a leaf-to-fruit ratio of 50-55:1; seventh, for on-year trees that set slightly more fruit, large-branch girdling can be carried out in August to September to promote flowering, so as to increase the number of flowers in the off year; eighth, in autumn, combine the application of heavy fertilizer with root cutting or water control, etc., to promote flower bud differentiation.
2. Pruning of off-year trees: Pruning of off-year trees refers to pruning after the on-year trees have been harvested. Because the on year bears too much fruit, consumes much nutrition, and produces few shoots, the tree vigor may even decline, nutrition is poor, flower bud differentiation is difficult, and the next year's fruiting is reduced, becoming an off-year tree. Pruning of off-year trees is best carried out from before bud break to before flower bud appearance. The pruning measures taken are: first, retain fruiting mother branches as much as possible; for summer and autumn shoots and weak spring vegetative shoots in the inner canopy, retain all those that can flower and fruit; second, short-prune and thin out weak branch groups on the periphery of the canopy and the summer and autumn fruiting mother branches after fruiting. When short-pruning, pay attention to selecting and retaining plump buds at the cut to renew the branch groups; third, after flowering and fruiting, carry out summer thinning, removing weak branch groups that have not flowered or fruited, so that the canopy is ventilated and light can penetrate, the shoots are robust, and the yield is increased; fourth, after fruit harvest, heavily cut back in winter, thin out crossing branches and declining branch groups, and also properly short-prune and rejuvenate the inner canopy branches.