Key Management Techniques for Jujube Orchards in Late Autumn and Early Winter

Clean the jujube orchard. Before winter arrives, after the jujube leaves fall, promptly sweep up fallen leaves, diseased and mummified fruit, weeds, and so on in the orchard, gather them together and burn them, so as to burn to death overwintering disease spores, mycelium, and insect eggs.

Plow and turn the jujube orchard. For jujube groves practicing jujube-grain intercropping, deep plow the soil between the plants and under the tree canopy; for those not practicing jujube-grain intercropping, plow and turn the entire orchard, and in particular the soil within the projected area under the tree canopy must be deep plowed. The closer to the trunk, the shallower the plowing should be; the farther from the trunk, the deeper the plowing, generally 15-30 cm is appropriate. In this way, the overwintering pupae and eggs in the soil can be turned out and frozen to death. This management measure can reduce the damage caused by many pests such as the jujube inchworm, jujube slug moth, jujube gall midge, weevil, red spider mite, scarab beetle, and the peach fruit borer.

Apply base fertilizer heavily. The most suitable time to apply base fertilizer is from after the jujube fruit harvest to before leaf fall, generally in early to mid-October. Generally, trees in the growth and fruiting stage are applied 30-80 kg of organic fertilizer per tree, mixed with 0.2-0.4 kg of urea and 0.5-1.0 kg of superphosphate; large trees in full fruiting stage are applied 100-200 kg of organic fertilizer per tree, mixed with 0.4-0.8 kg of urea and 1.0-2.5 kg of superphosphate.

Winter pruning. Pruning jujube trees can make the tree structure reasonable, improve the ventilation and light conditions of the tree body and the internal nutrient distribution, thereby achieving the goals of early fruiting, high yield, stable yield, and high quality for jujube trees.

(1) Pruning of jujube trees in the early fruiting stage: At this stage the tree canopy has not yet formed, and vegetative growth is still dominant. Pruning at this stage should focus mainly on thinning, retraction, heading back, and training, carried out according to the principle of "four keep, five do not keep." "Four keep" means: keep the outer jujube heads; keep the jujube heads on the scaffold branches; keep the robust, well-filled jujube heads with development potential; keep the jujube heads that have a large number of secondary branches and jujube spurs and strong fruiting capacity. "Five do not keep" means: do not keep drooping branches and weak branches; do not keep thin and weak slanting branches and overlapping branches; do not keep diseased and insect-damaged branches and dead branches; do not keep improperly positioned and underdeveloped water sprouts; do not keep whorled branches, crossing branches, twin branches, and water sprouts.

(2) Pruning of jujube trees in the full fruiting stage: At this stage the tree canopy has already formed, growth vigor weakens, the tree canopy is basically stable, and fruiting capacity is strong. In the later period, the tips of the scaffold branches gradually bend and droop, grow crossing each other, the inner canopy gradually dies, and the fruiting position moves outward. Therefore, pruning should adopt a combination of thinning and retraction, open up the light path, guide light into the inner canopy, cultivate inner canopy branches, prevent internal branches from dying and the fruiting position from moving outward, pay attention to the cultivation and renewal of fruiting branch groups, and extend the fruiting years.

(3) Renewal pruning of old jujube trees: As the tree age increases, the scaffold branches gradually die back, the tree canopy becomes smaller, growth noticeably weakens, the growth amount of jujube heads is small, jujube hanging branches are short, and fruiting capacity declines significantly. For such old trees, renewal pruning is needed to rejuvenate the tree vigor. The degree of renewal should be determined by the number of effective jujube spurs (that is, living jujube spurs). When an old jujube tree has 300-500 effective jujube spurs, heavy renewal should be carried out, that is, on the scaffold branches choose a vigorous spur growing outward, saw off 1/2-2/3 of the total length of the scaffold branch, and stop ringing the tree for 2-3 years to let it recover; when there are 500-1000 effective jujube spurs, medium renewal can be adopted, sawing off 1/4-1/3 of the total length of the scaffold branch, and stopping ringing the tree for 1-2 years; when there are 1000-1500 effective jujube spurs, light renewal can be carried out, sawing off 1/7-1/5 of the total length of the scaffold branch, and ringing can continue as usual.

Scrape off old tree bark. Some jujube tree pests such as the jujube leaf roller, jujube leaf gall mite, and red spider mite mostly overwinter in the cracks of jujube tree bark. Scraping off the old bark of jujube trees in winter can eliminate the overwintering pests.

Control diseases and pests. Before winter arrives or before bud break in early spring, spray the entire orchard once with 3-5 degrees lime-sulfur mixture to eliminate some of the overwintering pathogens and pests. For jujube orchards with serious occurrence of the tortoise wax scale, the method of brushing with a broom stub can be used for control; the method of spraying clean water onto the branches can also be used for control. When the water freezes, strike the branches with a pole, and the tortoise wax scale will fall off together with the ice film, and the control effect is also very good.