Why Does Schisandra Drop Its Flowers and Fruit? Causes and Control Methods

I. Causes of flower and fruit drop

1. Low-temperature freezing damage causes flower drop. In some areas of the east, the last frost period occurs in mid-May, and cold air masses cause physiological chilling injury, causing some flower buds to drop.

2. Herbicide drift causes flower drop. Field herbicides are mostly used in late April and early May, which is exactly the flowering period of Schisandra. Herbicide drift directly damages Schisandra petals, preventing female flowers from pollinating normally and causing flower drop.

3. Pests and diseases cause fruit drop. The main diseases are root rot, leaf blight, and powdery mildew, which cause fruit drop when they occur severely; the main pests are leaf roller, foam cicada, and tent caterpillar, all of which occur from May to August and directly damage the fruit when severe.

4. Imbalanced water and fertilizer management causes fruit drop. Spring drought and autumn drought occur frequently in various regions, and Schisandra without irrigation facilities struggles to survive; drought combined with fertilizer deficiency makes fruit drop even more pronounced.

5. Environmental pollution causes fruit drop. This is mainly exhaust gas emitted by chemical enterprises; acid rain then leads to frequent disease, and fruit drop occurs when control is not timely. Smoke emitted by coal-fired boilers can also cause carbon poisoning of Schisandra fruit.

II. Measures to control flower and fruit drop

1. For chilling injury, prevention should be the main approach; smoke can be released according to weather forecasts for control. In cultivation, growing strong seedlings and timely irrigation can be adopted to reduce freezing and chilling injury.

2. For the harm of herbicide drift, action must start at the source. The government can formulate village rules and conventions prohibiting the use of herbicides within 2000 m around Schisandra plots, set up warning signs, and once phytotoxicity occurs, spray agents to alleviate it, such as Penxiao + brassinolide or Xian U Su, Fu'er 655, etc., which can alleviate the symptoms of damage.

3. Pests and diseases should be controlled promptly, and diseases should be managed with prevention as the main approach and integrated control. For root rot, 50% carbendazim wettable powder 500 times solution or 70% thiophanate-methyl wettable powder 1000 times solution can be used to drench the roots; for leaf blight, 50% thiophanate-methyl wettable powder 1000 times solution or 70% mancozeb wettable powder 500-1000 times solution, or 3% jinggangmycin diluted with water can be sprayed for control; for leaf roller, foam cicada, tent caterpillar, etc., 2.5% deltamethrin emulsifiable concentrate 3000-4000 times solution or 40% omethoate emulsifiable concentrate 1000-1500 times solution can be sprayed for control.

4. Strengthen field management, equip micro-sprinkler and drip irrigation facilities, and irrigate in combination with topdressing. Topdressing should mainly use compound fertilizer and special-purpose fertilizer, with appropriate supplementation of trace elements such as iron, zinc, and selenium, to ensure sufficient nutrient supply.

5. Schisandra orchards should be built away from industrial pollution areas and away from highways. They should be built according to pollution-free production standards, cultivation techniques should be standardized, and the use of pesticides and chemical fertilizers should be minimized as much as possible. Diseases caused by acid rain should be controlled promptly to ensure the goal of high yield, high quality, and high efficiency.