Optimizing Jujube Fruit Production: Strategies to Combat Fruit Cracking and Preharvest Drop

Mar 21

20:10

2024

David Yvon

Jujube fruit, a staple in many diets around the world, faces a significant challenge during its maturation period: fruit cracking. This phenomenon can affect 10% to 30% of the total jujube production, leading to substantial losses for growers. The cracking typically occurs as the fruit transitions from full red coloring to the red crisp ripe stage, particularly in early maturing varieties that flower around mid-September. However, late-maturing varieties that ripen in October and beyond are less prone to this issue. Cracking is more prevalent in years when the rainy season ends early, followed by a drought period from mid-August to early September. Conversely, in years with a late rainy season and subsequent drought, even susceptible varieties are less likely to crack.

Preventative Measures Against Fruit Cracking

To mitigate the risk of jujube fruit cracking, several strategies can be employed:

Selection of Resistant Varieties: Choosing jujube varieties that are less prone to cracking is a fundamental step in addressing this issue.
Calcium Chloride Sprays: From late July, spraying a 3g/kg calcium chloride solution every 15 days until harvest can strengthen fruit skin and reduce cracking.
Lime Solution Application: In late August, a 50 to 100 times diluted lime solution can be sprayed on the fruit surface to prevent cracking.
Irrigation Management: Maintaining soil moisture levels between 12% to 14% through irrigation during drought periods, using mulch or straw to reduce evaporation, and ensuring proper drainage can stabilize soil water content and significantly lower the rate of cracking.
Timely Harvesting: Harvesting and processing early-cracking varieties at the right time can prevent losses due to cracking.

Addressing Preharvest Fruit Drop

Preharvest fruit drop, another challenge for jujube growers, can be prevented by applying naphthalene acetic acid (NAA) or pimacol. Spraying a 50 to 70 mg/kg concentration of NAA or pimacol 10 to 15 days before the fruit matures can delay the disintegration of the abscission cells, allowing the fruit to reach full maturity before normal harvesting. NAA does not dissolve directly in water and must be dissolved in alcohol or boiling water before dilution. Pimacol, on the other hand, is water-soluble and more convenient to use. It's important to note that NAA and pimacol should not be mixed with alkaline pesticides.

Alternative Growth Regulators

PCPA (chlorinated acetic acid) is another growth regulator that can be used to prevent preharvest fruit drop. A concentration of 10 to 20 mg/kg applied at the same time as NAA can be effective.

Harvesting Considerations

After applying growth regulators like NAA, it may be necessary to delay the harvest to ensure optimal ripeness and ease of picking. If harvesting becomes difficult, postponing the harvest or applying a 200 mg/kg concentration of ethephon can promote ripening and facilitate harvesting.

Interesting Stats and Data

Jujube trees can produce between 40 to 100 pounds of fruit per season (California Rare Fruit Growers, Inc.).
China is the largest producer of jujubes, with an annual production of about 6 million tons, accounting for over 90% of the world's total (FAO).

Sources

The information in this article is based on agricultural best practices and has been fact-checked against authoritative sources. For more information on jujube cultivation, visit the California Rare Fruit Growers, Inc. and the Food and Agriculture Organization of the United Nations (FAO).

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