Winter Jujube Turning White: What to Do? Key Points of Control Techniques Explained

SummaryReasonable water and fertilizer: When the jujube fruit enters the white-ripe stage, potassium fertilizer can be increased, nitrogen fertilizer should not be applied; young trees and weak trees should be watered less, and strong trees and medium-vigor trees do not need watering. Managing the girdled ring: If the weak girdled ring has not healed, cytokinin can be applied by smearing, then the girdled ring should be tied tightly with plastic; for girdled rings that have already healed, vigorous trees and medium-vigor trees can undergo a second girdling, while weak trees should not be girdled. Promoting color change: Guoguang potassium mixed with Guoguang Tiandu can be sprayed on the leaves. Cooling the greenhouse: Cover with a shade net during high-temperature periods.

The whitening technique of jujube trees determines the coloring effect of winter jujube fruit in the later stage. The white-ripe stage of winter jujube refers to the decline of chlorophyll content in the peel cells, when the background color of the peel fades from green and appears whitish. At this time, the flesh of the jujube fruit gradually becomes soft, so mastering the key points of the whitening technique plays a key role in the later coloring and ripening of the jujube fruit.

I. Reasonable Water and Fertilizer

1. When the jujube fruit enters the white-ripe stage, it will accelerate the accumulation of sugar and dry matter during this period. Potassium fertilizer should be increased, and nitrogen fertilizer should not be applied, because nitrogen fertilizer easily causes the jujube fruit to remain green and ripen late, thereby delaying the ripening time. A fertilizer applicator can be used for fertilization, and about 5-8 kg of Guoguang potassium can be applied per mu.

2. During the white-ripe stage, watering can be done appropriately according to the specific growth conditions of the saplings. Young trees and weak trees can be watered a small amount, while strong trees and medium-vigor trees do not need watering. Excessive watering will cause the jujube fruit to remain green, thereby affecting the ripening time.

II. Managing the Girdled Ring

1. After winter jujube enters the white-ripe stage, girdled ring management must be strengthened. If the girdled ring is found to have not healed for a long time, it should be treated promptly. Gibberellic acid and cytokinin can be smeared on the girdled ring, and then the girdled ring can be tightly bound with plastic film.

2. If the girdled ring has already healed, a second girdling can be decided according to the specific tree vigor. Both medium-vigor trees and vigorous trees can undergo a second girdling. The width of the girdled ring can be determined according to tree vigor and fruit load, and it should not be too wide, as it easily causes tree death. For weak trees, the method of multiple ring cuts can be used, with one ring cut every 5-7 days, and a second girdling should not be performed.

III. Promoting Color Change

The speed at which the jujube fruit loses green directly affects the speed of later coloring of the jujube fruit. In order to promote the background color of the jujube fruit to turn white, Guoguang potassium mixed with Guoguang Tiandu can be sprayed on the leaves, once every 7-10 days, for 2-3 consecutive sprays, which helps improve the smoothness and gloss of the fruit surface and increase the content of sugar and dry matter in the jujube fruit.

IV. Cooling the Greenhouse

If high-temperature weather causes the temperature inside the greenhouse to rise, it will affect the normal growth of the jujube fruit, and corresponding cooling measures should be taken. According to local climate conditions, a layer of shade net can be covered during high-temperature periods, or mud slurry can be splashed for cooling, but it is not easy to spray evenly, long-term covering affects photosynthesis, and it is easily washed off by rain.

V. Preventing and Controlling Pests and Diseases

During the white-ripe stage, if the jujube fruit encounters high-humidity and high-temperature climate, it is prone to pests and diseases, such as fruit cracking disease, anthracnose, fruit shrinkage disease, etc. Tebuconazole, propineb, thiophanate-methyl, pyraclostrobin, prochloraz, etc. can be used for control. The main insect pests include fruit borers, red spider mites, jujube gall mites, etc., and emamectin benzoate, spirodiclofen, pyrethroids, abamectin, etc. can be selected for control.