Causes:
First, the nutritional imbalance, the lack of calcium in the soil, tomatoes can not absorb enough calcium from the soil, and too much nitrogen, nutrient growth is excessive, affect the absorption of calcium, causing physiology disorders around the umbilical cells, causing umbilical rot disease.
Second, the imbalance or instability of soil moisture supply, especially in the result period of drought, when the water supply is insufficient, the watering is not timely, the soil moisture changes violently, the young fruit and the green umbilicus cause a large number of water loss and cause tissue necrosis; or the application of unrefined fertilizer Or fertilizer is too thick to cause root burning and affect the normal absorption of water. In particular, partial application of nitrogen fertilizer causes plants to grow long, and the lack of increased calcium can also cause umbilical rot. In addition, irregular seedlings may also cause the occurrence of partial plant umbilical rot.
Precaution:
1. Foliar application of calcium and boron fertilizers: During the expansion of tomato fruits, calcium and boron fertilizers containing higher concentrations are selected. About 45 kg of spray fertilizer is applied per mu, and 50 g of boron fertilizer is added for every 15 kg of water + calcium fertilizer. Mix 150 grams of spray. Spray 7 days later. For tomatoes with mild symptoms of umbilical rot, adding a broad-spectrum fungicide such as chlorothalonil or carbendazim when spraying foliar fertilizer can prevent the occurrence of other diseases. For the fruit with severe symptoms of umbilical rot, early picking and treatment, and timely application of boron and calcium fertilizer to prevent the emergence of tender fruit.
2. Balanced fertilization: To avoid the use of high-potassium fertilizer, tomatoes should be top-dressed or fertilized. It is best to use a compound fertilizer with a balanced ratio of nitrogen, phosphorus and potassium (1:1:1) so as to avoid affecting the absorption of calcium by the higher concentration of potassium in the soil. Organic fertilizers should be added to increase the permeability of the soil and improve the plant's root absorption environment. The pH of the soil is adjusted to neutral, and lime soil fertilizer should be added to the acidic soil in time to avoid continuous cropping.
3. Anti-drug drainage: Summer often encounters high temperature and drought or heavy rain. If the soil is too dry or too wet, it will affect the normal absorption of calcium by roots, and it is easy to induce the disease. It should be ensured that the soil is dry and wet. When it encounters dry weather, it must be watered in time, and in the event of heavy rain, it must be drained in time.
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