Key Management Techniques for Zanhuang Jujube at the White-Ripe Stage

At the white-ripe stage, the fruit of Zanhuang jujube has basically reached the shape and size inherent to the variety; the peel is thin, chlorophyll in the cells is greatly reduced, and the color changes from green to greenish-white or milky white; the flesh is greenish-white, relatively loose in texture, with little juice and low sugar content. The white-ripe stage of jujube trees is a key phase in managing jujubes for reddening, and at this time management should pay attention to the following aspects:

I. Do a good job of pest and disease control

1. Anthracnose. Fruit symptoms can be seen in early to mid-August, and if there is high temperature and frequent rain later, infection accelerates. For control, from late July to mid-August, in conjunction with controlling jujube rust, spray 1 to 2 applications of double-strength Bordeaux mixture to also prevent anthracnose pathogens from infecting jujube fruit; from late August to early September, spray 12% copper octanoate 700 to 800 times dilution 2 to 3 times, and generally stop applying chemicals after mid-September.

2. Fruit shrinkage disease (iron peel disease). Symptoms generally appear in August during the white-ripe stage of jujube fruit, and can spread suddenly when rain occurs, with the peak incidence from mid-to-late August to September. Spray 0.3% borax or boric acid solution at the young fruit stage; from late July to early August during the white-ripe stage of jujube fruit, use 75% chlorothalonil wettable powder 600 times dilution or 80% Daconil M-45, etc. for control, with obvious effectiveness, or spray 2 applications of agricultural streptomycin at 100 to 140 units/ml or oxytetracycline at 140 to 210 units/ml.

3. Fruit cracking disease. In mid-to-late August there are often continuous rainy days, and fruit cracking can be seen. Control methods: First, during the white-ripe stage of jujube fruit, irrigate promptly according to climate and drought conditions to prevent drought, or before the rainy season arrives cover the jujube orchard with grass or plastic film to maintain soil moisture. Second, appropriately supplement calcium fertilizer in the middle and late stages of fruit growth, such as a mixed solution of 0.2% calcium chloride or calcium nitrate and monopotassium phosphate; during calcium spraying, control the amount of nitrogen fertilizer applied to prevent excessive nitrogen from consuming calcium. Third, after young fruit set, spray 1000 times fruit-tree-specific Tianda 2116, once every half month, for 3 to 4 consecutive applications, which can effectively prevent jujube fruit cracking. Fourth, 2 to 3 days before rain, spray "plant protection film" and other fruit-preserving agents to prevent fruit cracking, once every 7 to 10 days, for 2 to 3 consecutive applications. Fifth, before jujube fruit enters the white-ripe stage, promptly build a rain shelter, and when the white-ripe stage approaches, promptly cover the shelter film to prevent continuous rain from causing fruit cracking.

4. Insect pests. Insect pests at this stage mainly include scale insects, red spiders, stink bugs, peach fruit borers, longhorn beetles, etc. Pesticides can be used in a targeted manner against the pests. A mixed solution of 1.8% abamectin emulsifiable concentrate 2000 to 2500 times dilution and 30% chlorpyrifos can be used, or a mixed solution with 70% imidacloprid or 4.5% beta-cypermethrin emulsifiable concentrate 1000 to 2000 times dilution. Stop applying chemicals in mid-September.

II. Do a good job of fertilizing and pruning

1. Apply coloring fertilizer. During the white-ripe stage of jujube fruit, mix-spray 0.4% monopotassium phosphate solution together with liquid pesticide spraying. Before rain, broadcast wood ash, monopotassium phosphate and other fertilizers under the tree canopy.

2. Pruning. Because the fruit quality of red jujube is affected by carbon dioxide and light, there are significant differences in single fruit weight, color, hardness, and soluble solids content. Mature low-yield jujube orchards should reduce the number of main branch tiers and the order of scaffold branches, increase the spacing between tiers, reduce the thickness of the leaf canopy layer and the crown width, and increase the opening angle of main and lateral branches, so as to facilitate rapid drying of the fruit surface after rain.

Zanhuang County Forestry and Tourism Bureau Lei Ling, Shang Sujuan, Yu Junjie