Tomato Flower and Fruit Drop and Its Prevention and Control

If tomatoes have falling flowers and fruits, it will greatly affect the yield. So what should we do if this phenomenon occurs?

1. Reasons for tomato flower and fruit drop

1. Diseases and pests cause flowers and fruits to fall off. Tomatoes are damaged by many diseases and pests from planting to harvesting: 1. Virus diseases cause flower buds to turn brown first and then fall off. Fruits are deformed or rotten, basically losing their commercial value. At the same time, leaves curl and discolor, affecting photosynthesis, which can also cause flowers and fruits to fall off. In general years, 20%-30% of them fall off, and in severe cases, more than 70% fall off. ② Gray mold causes flower buds to shrink. ③ Early blight turns leaves brown and loses photosynthesis. ④ Anthracnose produces large brown spots on the fruit, which then rots. ⑤ Sunburn causes the peel to turn white under strong direct light, attracting pathogens to invade and causing the fruit to rot. 6. Soft rot causes the fruit to become smelly and sap-flowing, leaving only empty skin. 7. Whiteflies suck the juice of stems and leaves, causing nutrient consumption and mottled fruits, and also spread viral diseases. Bollworms, corn borers, etc., which bore into the fruit, can also cause rotten fruit.

2. Malnutrition causes flower and fruit drop. Irrational fertilization leads to imbalance between vegetative growth and reproductive growth, which is manifested in excessive growth of branches and leaves, and the heavy burden on the plant. This results in no fruit set or most of the flowers and fruits falling. Poor management, failure to timely prune and thin flowers and fruits, causes nutrient loss. Uneven land, water accumulation on the surface after irrigation or heavy rain, causes poor root breathing and hindered nutrient absorption. In mild cases, flowers and fruits fall, and in severe cases, the entire plant dies.

3. Harsh environment leads to flower and fruit drop. High temperature and drought promote plant aging and premature aging, and induce viral diseases, causing flower and fruit drop. Continuous rain and cloudy weather lead to decreased photosynthetic function of plants, lack of fertilizer and yellowing, causing disease epidemics, root rot, seedling death, and yellowing and falling of flowers and fruits. Strong winds, heavy rains and hail can also cause some flowers and fruits to drop.

2. How to prevent tomato flowers and fruits from falling

1. Cultivate strong seedlings. Strong seedlings can improve the survival rate and stress resistance after transplanting. The selection of varieties with strong stress resistance is a prerequisite. At present, the new disease-resistant and high-yield varieties mainly include Zhonghong No. 1, Maohong, Taiwan Red, and Lisheng series. The nutrient soil should be reasonably prepared. The proportion is 40% of fertile garden soil and fully decomposed horse manure, and 20% of old slag. After mixing, add 1000-1500 grams of nitrate phosphorus per cubic meter and stir well. Seed treatment can be soaked first, and then germinated and sown after temperature change treatment to improve the cold resistance and stress resistance of seedlings. In order to make the root system of seedlings develop, pesticides and fungicides should not be mixed into the subsoil, but should be mixed into the covering soil. The temperature and humidity should be controlled during the seedling stage to ensure sufficient light time so that the seedlings can carry out vigorous photosynthesis. When the humidity on the bed surface is high, pulling up the seedlings to promote growth and applying wood ash can play a role in reducing humidity and strengthening the stalks. The standard for strong seedlings is short internodes, thick leaves, strong stems, dark green all over the plant, and it bounces back immediately when pressed lightly by hand.

When the seedlings have 3-4 true leaves, they are divided and transplanted to promote the increase of root hairs. After the seedlings survive, they can be planted in about 7 days. The seedlings cultivated in this way have less diseases, fewer weak seedlings, and strong resistance to adversity. The survival rate after planting can be increased by more than 13%.

2. Scientific management: Choose neutral loam that can be irrigated and drained well, and implement crop rotation for more than three years. Ridge and cover with film, which can adjust nutrition, protect soil temperature and humidity, and the film will reflect light in the later stage, which can accelerate the coloring of fruits. ① Fertilization should be "three foundations and three inputs": that is, basal fertilizer is the main fertilizer, supplemented by topdressing, pre-organic fertilizer is the main fertilizer, supplemented by chemical fertilizer; root application is the main fertilizer, supplemented by foliar spraying. Chemical fertilizers should be nitrogen,

Phosphorus and potassium should be applied together, and more phosphorus and potassium fertilizers should be applied appropriately. They should be mixed with organic fertilizers and fermented in advance so that they can be infiltrated into organic fertilizers to reduce nutrient loss. ② The seedlings are planted on both sides of the mulched ridges. Generally, about 4,000 seedlings are left per mu. During the seedling stage, reasonable pruning should be carried out, and side branches should be removed in time to avoid nutrient consumption. ③ In the mid- and late-stage management, "three suitable" measures should be taken: timely shading (covering the fruit with grass); timely adjusting the temperature (not higher than 30℃ during the day and not lower than 15℃ at night), spraying water on the leaves to cool down when the temperature is high at noon; timely inter-cultivation, soil cultivation, and prevention of falling. ④ Three precautions for watering: water as soon as the soil is dry, water frequently with small amounts of water instead of flooding with large amounts of water, and remove the accumulated water in time. ⑤ Insert the rack when the plant height is about 25 cm, and tie the branches in time after the fruit is produced, which can prevent the fruit from rotting on the ground, and improve the ventilation and light transmission environment in the field, which is conducive to fruit ripening. ⑤ Keep flowers and fruits reasonably, remove weak flowers and fruits in time, apply human feces and urine in combination with watering after fruiting, and then do not hoe to prevent premature aging of the plant and cause fruit drop. After 5-6 batches of fruit clusters grow, timely pinch the top and remove the old and yellow leaves at the bottom to increase the number of large and good fruits.

3. Prevention is the main method for pest control. Strengthen inspection and carry out timely and targeted prevention and control. ① To prevent and control viral diseases, seeds can be soaked in 10% trisodium phosphate for 15 minutes, then washed with clean water 3 times to germinate and eliminate viruses in seeds. Spray 2-3 times in the first period.

1000 times of NS-83 resistance enhancer for prevention. Use 300-500 times of virus A spray at the early stage of the disease, spray again after 7-10 days, and spray 2-3 times for yellow. During this period, you can spray foliar treasure or 0.1%-0.2% potassium dihydrogen phosphate 2-3 times to treat viruses and supplement nutrients to improve the plant's own disease resistance. ② To prevent and control fungal diseases such as anthracnose, gray mold, and early blight, it is advisable to use 800-1000 times of metalaxyl and 40O-50O times of disinfectant alum for spraying, spray once every 7-10 days, and spray 2-3 times in total to prevent the disease from spreading. ③ For bacterial diseases such as soft rot, you can spray 10O-150 ml/kg of streptomycin on the fruit surface, spray once every 7-10 days, and spray twice. 4. For sunburn, you can cover the fruit surface with grass for prevention. ⑤ For the prevention and control of whiteflies, you can use Bifenthion or 3000-4000 times diluted spray. ⑤ For borers such as cotton bollworm and corn borer, you can spray cotton bollworm or 1000 times diluted methomyl or 2000 times diluted kemobao during the egg peak period, spray three times every 7-10 days, and 2-3 times of application can control it.

4. Harvest the fruits in time when they are ripe to prevent disease infection. At the same time, remove the diseased, rotten and insect-infested fruits and bury them deep outside the garden to prevent human infection. After harvesting a batch of fruits, topdressing and watering should be carried out in time according to the growth of the plants to prevent premature aging, promote the delivery of nutrients to immature flowers and fruits, and ensure the yield and quality of the fruits in the later period.