Causes of and Control Methods for Tomato Flower and Fruit Drop
Tomato fruits are nutritious and have a distinctive flavor; they can be eaten raw or cooked, and are currently widely cultivated in China, but in some areas, flower and fruit drop tends to occur during the growing process. So, what causes tomato flower and fruit drop? How can it be controlled?
1. What causes tomato flower and fruit drop?
1. Abnormal temperature
Temperatures that are too high or too low can both cause defects in the flower organs, thereby leading to flower and fruit drop. Relevant data show that when the night temperature is below 15°C or above 22°C, or the daytime temperature is above 35°C, tomatoes will experience a large amount of flower drop.
2. Excessive vegetative growth of the plant
The high-temperature and high-humidity conditions of summer easily cause excessive vegetative growth of the plant, ultimately leading to flower and fruit drop, so attention must be paid to controlling this.
3. Boron deficiency
In some areas, boron deficiency can also cause a large amount of flower and fruit drop in tomatoes, so attention must be paid to applying sufficient boron fertilizer in the base fertilizer.
4. Improper soil and air humidity
Too much or too little moisture can both cause flower and fruit drop. For example, excessive soil moisture easily causes leggy growth, resulting in flower drop; if moisture is lacking and the soil becomes dry, it easily causes the formation of an abscission layer, resulting in a large amount of flower and fruit drop.
2. How can tomato flower and fruit drop be controlled?
1. Regulation of temperature and light conditions
Relevant data show that when the night temperature is below 15°C or above 22°C, or the daytime temperature is above 35°C, tomatoes will experience a large amount of flower drop. Therefore, during the fruit-setting and flowering stages of tomatoes, the temperature must be kept within this range. In addition, when summer temperatures are too high, in order to protect flowers and fruits, the concentration of the flower-setting agent should be reduced; 2,4-D or 4-CPA (fruit-setting hormone) can be used to protect flowers and fruits. If 2,4-D is used, its suitable concentration is 15 mg/kg; if 4-CPA is used, its suitable concentration is 25 mg/kg. Be careful not to apply the solution to the heart leaves and young stems, to prevent hormone poisoning.
2. Fertilizer and water management
Fertilization: apply sufficient boron fertilizer in the base fertilizer, and during the flowering stage, pay attention to spraying a boron-containing foliar fertilizer on the leaves.
Watering: from the seedling recovery stage until the first truss has set fruit, water appropriately less to prevent leggy growth of the plant and the resulting flower and fruit drop. When the first truss swells and the second truss has set fruit, increase the frequency of watering, and water in a timely manner when the young fruits are swelling.
3. Plant training
Single-stem training or double-stem training can be used. With single-stem training, keep about 7 trusses per plant. The first truss can keep 3 fruits; for the second to fifth trusses, keep 3-4 fruits per truss and remove the excess. Remove side shoots at the right time and thin flowers and fruits in a timely manner to keep the fruits large and uniform. Generally, first keep 5-6 fruits per truss, and when the fruits grow to about 2 cm in diameter, remove the deformed fruits and diseased or insect-damaged fruits, keeping 4-5 fruits. However, the first few trusses must not be allowed to bear too many fruits, to prevent nutrients from being concentrated on supplying the swelling of the fruits, which would cause severe flower and fruit drop on the upper part.
4. Pest and disease control
The main diseases include early blight, gray mold, bacterial canker, and streak virus disease. It is recommended to do a good job of chemical prevention. Early blight and gray mold are fungal diseases and can be prevented with chlorothalonil, thiophanate-methyl, or carbendazim; bacterial canker is a bacterial disease, and chemical prevention uses agricultural streptomycin or copper-based preparations (DT, copper oxychloride, etc.); to prevent viral diseases, spray moroxydine·copper acetate (Virus A) + ningnanmycin, and at the same time pay attention to applying imidacloprid or acetamiprid to control pests such as whiteflies and aphids, because they easily carry and transmit viruses.
Overall, the main causes of tomato flower and fruit drop are abnormal temperature, excessive vegetative growth of the plant, boron deficiency, and improper humidity. When growing tomatoes, growers should pay attention to these aspects and take corresponding preventive measures, which can effectively control flower and fruit drop.