In 2006, Yuncheng Dongzao in Shanxi Province faced several common issues with its winter jujube trees, including a low number of flower buds, poor bud quality, heavy and small buds, low fruit setting rates, and overall poor fruit production. Some date gardens were even left barren. A sample survey conducted in mid-July of the same year across eight key jujube-producing counties showed that the yield had dropped by 30-40% compared to the previous year. This prompted the author to conduct an in-depth investigation into the abnormal flowering and fruit drop phenomenon observed in the region.
**Causes of Abnormal Flowering and Fruit Drop**
1. **Natural Factors**
(1) **Frost Damage**: In early April 2006, temperatures in Yuncheng rose sharply, reaching up to 29°C. However, on the night of April 11th, a sudden cold snap from Siberia hit the area, causing snowfall in several counties such as Pinglu, Lucheng, Wanrong, Yuanqu, and Qixian, with snow depths ranging from 8 cm to as much as 15 cm. Other areas experienced rainfall, with minimum nighttime temperatures dropping to 0°C. According to meteorological data, from April 13th to 19th, temperatures remained unusually low, with some regions experiencing frost and temperatures as low as -5°C to -1°C. This caused significant frost damage to jujube trees during budding. Farmers reported that many buds were either unable to germinate or were frozen after sprouting, leading to a delay in the flowering period by about 15 days. The new buds were weak, pale, and often lacked flowers, contributing to a 30% higher than normal flowering rate but with poor quality.
(2) **High Temperatures**: On June 15, 2006, Yuncheng experienced its first heatwave, with temperatures exceeding 37°C in several areas like Salt Lake, Laoshan, Yongji, Pinglu, Xiaxian, and Hejin. The high temperatures continued until June 19th, peaking at 42.2°C. Only after a moderate to heavy rain on June 20th did the weather slightly cool down. This was the second consecutive year of abnormal high temperatures in June since 1966. Such extreme heat disrupted the accumulation of organic nutrients in jujube trees, resulting in open flowers that failed to set fruit and premature fruit drop. According to surveys, the young fruit shedding rate reached around 20%, while in some cases it climbed as high as 80%.
(3) **Pest Infestation**: During the flowering period, the main pest targeted in Yuncheng’s jujube areas was *Lepidosaphes lucorum* (green plague). In 2006, farmers made progress in controlling juvenile scorpion larvae. However, due to climatic changes, the hatching of *L. lucorum* was delayed until early June. Many farmers assumed the infestation period had passed and neglected late-stage control. After two light rains on June 2nd and 3rd, the pest population thrived under favorable conditions. By the time farmers noticed the damage, the pests had already affected the jujube buds, leading to significant losses in both flowers and fruits. Surveys indicated that approximately 60% of the jujube gardens in Yuncheng suffered from fruit drop due to green plague infestations.
2. **Human Factors**
(1) **Nutrient Deficiency**: Surveys revealed that 30% of demonstration parks had excessive fruiting in 2005, but in 2006, they experienced empty branches, no buds, and weak flower buds. Further investigation found that insufficient fertilizer application in the fall of 2005 and only minimal fertilization in spring 2006 could not meet the tree's nutritional needs. As a result, the fruit development stage saw leaves turning yellow, wilting, and falling off. The root cause was inadequate nutrient supply to the trees.
(2) **Poor Wound Healing**: Jujube cultivation often involves girdling, but some farmers improperly performed this practice, damaging the xylem and causing wounds that failed to heal. This led to tree decline, yellowing leaves, and fruit loss, with severe cases resulting in dead trees.
**Defense Measures**
1. **Frost Protection**: Apply base fertilizer early, increase organic matter, and use available nitrogen and phosphorus to enhance tree resilience. Before freezing events, spray antifreeze solutions such as 200 times diluted high-fat film or 100–200 times diluted hydroxymethyl cellulose. For already damaged gardens, apply 5° Baum lime sulfur.
2. **Heat Stress Management**: Spray plant ash leaching solution (2.5 kg of grass ash soaked in 50 kg of water for 15 hours, then filtered) at night to reduce heat stress. Alternatively, use rice vinegar (250 grams per 50 kg of water) to prevent drought. Ensure regular irrigation to maintain soil moisture and support healthy fruit development.
3. **Pest Control**: Establish monitoring points at village level, assign专人 (special personnel) to track pest activity, and provide timely warnings to improve prevention strategies.
4. **Improve Tree Nutrition**: Prioritize the use of organic fertilizer or compost in jujube gardens to ensure adequate nutrition.
5. **Proper Girdling Techniques**: In concentrated jujube planting areas, train professional teams to perform girdling correctly to avoid tree damage and promote better yields.
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