Detailed Prevention and Control Methods for Low Fruit Set Rate in Jujube Trees

1. Pay attention to shaping and pruning. Because the bud types and growth and fruiting habits of jujube trees differ from those of other fruit trees, they are not sensitive to pruning responses. Therefore, pruning must follow the tree's natural tendency and shape the tree according to the branches, and pruning should be light. Winter pruning and summer pruning should be combined so that the main branches are reasonably distributed with clear layers. After selecting and retaining large branches with good direction and a large bearing load, overly dense branches, crossing branches, and diseased and pest-infested branches should be removed from the base without hesitation. Shorten the already weakened jujube heads, and cut off 1 to 2 secondary branches near the cut, so that they sprout new jujube heads, which is the so-called “two cuts.” The drooping parts of the scaffold branches should be properly retracted to balance the tree vigor inside and outside and prevent the fruiting part from moving outward. For those that have already been bent down and have sprouted new jujube heads at the bend, retract them.

2. Control the vegetative growth of the tree. Root cutting: for young vigorous trees, part of the root system can be cut. Pinching jujube heads: after jujube heads sprout, they grow quickly? and consume many nutrients. Where there are too many and too dense jujube heads, pinch them in June at 1/3 of the jujube head length, which can concentrate nutrients and increase the fruit set rate.

3. Irrigation and water spraying during the flowering period. Flowering and the construction of various organs require a large amount of water during the flowering period, so irrigation should be carried out during the flowering period. During full bloom, spray clear water once in the morning and once in the evening every day to increase air humidity, so as to facilitate flower development and increase the fruit set rate.

4. Change nutrient transport. For trees entering full fruit-bearing age with trunk diameter above 10 to 12 cm, ring-barking can be done in early full bloom when the weather is clear. When ring-barking, first scrape off the old bark to expose the white phloem, then use a ring-barking knife or cutting and grafting tool to girdle one round, reaching the xylem, with a width of 0.3 to 0.6 cm? It generally heals in 20 to 25 days. In the first year, start 10 to 20 cm from the ground, and in subsequent years open upward year by year. Do not reopen at the original girdling opening. The girdling openings between two years should be 3 to 5 cm apart. After ring-barking reaches the main branch fork, then open a “return ring” from bottom to top. At the opening, apply a stomach poison or contact insecticide with a long residual effect to prevent larvae of the bark-eating moth from boring into and feeding on the healing tissue.

5. Place bees in the jujube orchard. Jujube flowers have well-developed nectar discs, and when in full bloom the nectar is abundant and the fragrance is strong, making them typical insect-pollinated flowers. Placing bees can increase the fruit set rate.

6. Application of growth regulators. Spraying 10 mg/kg of 920 during full bloom can increase the fruit set rate.