What are the key technical points for post-harvest management of jujube trees?

1. Apply fruit-harvest fertilizer well. Apply fruit-harvest fertilizer once 3-4 days before harvest or 5-7 days after harvest. Generally apply 50-60 kg of organic fertilizer per jujube tree, applying it by the trenching method at the base of the main trunk of the jujube tree, and cover with soil immediately after application.

2. Spray quick-acting fertilizer. Immediately after harvest, spray 0.3-0.4% urea solution and 0.4%-0.5% potassium dihydrogen phosphate solution on the leaves to avoid leaf drop, improve photosynthetic efficiency after harvest, accumulate and increase tree nutrients, promote more flower bud differentiation, and reduce flower and fruit drop the following year.

3. Bury fertilizer and earth up. In winter, earth up about 17-33 cm thick within a 1 m radius of the canopy, which can enhance drought resistance and the ability to retain moisture and fertilizer. For jujube orchards with poor soil, lacking organic matter, and a shallow plow layer, deep plowing and trenching can be done to bury fertilizer and improve the soil, so as to deepen the plow layer, increase soil porosity, and improve fertility. Apply 3000 kg of organic fertilizer per mu.

4. Pruning and branch training. Winter pruning is generally carried out after the jujube tree sheds its leaves, mainly removing dead branches, diseased and pest-infested branches, overlapping branches, weak slender branches, water sprouts, and aged branches, etc. In winter pruning, care should be taken to retain the extension branches of the main scaffold branches at all levels, with smooth pruning cuts, without damaging the tree body.

5. Apply wintering fertilizer well. Apply winter fertilizer once before overwintering to lay a good foundation for promoting growth and increasing yield the following year. Generally, circular trench application is adopted, that is, digging a trench vertically below the edge of the canopy with a depth of 20-30 cm and a width of 30 cm, applying 40-50 kg of decomposed pig and cattle manure or 100 kg of decomposed compost, 3 kg of superphosphate, 1 kg of potassium chloride, and 1 kg of human and livestock manure per tree, and covering with soil promptly after application.

6. Prevent and control diseases and pests. In combination with winter soil plowing, overwintering insects in the soil under the trees can be collected and burned. Before the larvae emerge from the soil, irrigate the ground with 500-fold dilution of 5% phoxim, or broadcast about 100 g of 2.5% methyl parathion powder to kill the larvae. To control the jujube leaf roller, methods such as plugging and sealing tree holes, scraping off old bark, and digging over the tree can be used to eliminate overwintering pupae and reduce damage the following year.