Tomato rot disease mainly occurs during fruit enlargement to maturity, and is most common on the first and second ear fruits. The symptoms of the disease are obvious during the red period.
First, the harm symptoms
Typical symptoms are uneven coloration of the fruit and brown vascular bundles. The vascular bundles in the epidermis of the diseased light fruit became brown, and a dark brown streak appeared from the vicinity of the stalk to the umbilicus. The shape of the fruit surface did not change much, but the epidermis of the vascular bundle was delayed in coloration and it was difficult to turn red. In severely diseased fruits, all the vascular bundles in the fruit were dark brown, and green spots appeared on the surface of the fruit. In severe cases, the lesions were pale brown, and the pulp became hard and some of the fruits became empty.
Tomato rot and virus disease are easily confused. The tendon rot is a physiological disease, and the vascular bundles in the fruit become brown, resulting in a poorly colored surface of the diseased part of the fruit and green spots. Virus disease is an infective disease. The epidermis at the site of disease is brown, and the inward expansion of the disease causes the vascular bundle to become brown.
Second, the cause of the disease
1. Nitrogen in the soil, especially ammonia nitrogen is too much, potassium deficiency, boron, calcium and other elements in the tomato. Unfermented organic fertilizer is applied.
2. Insufficient illumination, low temperature and humidity, especially low temperature and low illumination during the result, coupled with dense plants, poor ventilation, and insufficient carbon dioxide content, affect the accumulation of photosynthetic products and normal metabolic functions, resulting in browning and lignification of vascular bundles.
3. Soil compaction, poor permeability, or soil moisture is too high, the ground temperature is too low, etc., impede the absorption of nutrients and moisture in the root system.
4. Related to the variety.
Third, preventive measures
1. Selection of disease-resistant varieties, the general powder fruit type is more resistant than the red fruit type, and the small fruit type is more resistant than the big fruit type.
2. The rotation is down. For heavy sheds, crop rotation can be carried out to reduce the imbalance of soil nutrients.
3. Increase the application of decomposed organic fertilizer, potash fertilizer, and microbiological fertilizer to improve the physical properties of the soil, and improve soil water storage capacity and permeability. Appropriate amount of chemical fertilizers is used to control the amount of nitrogenous fertilizers, especially ammoniacal nitrogen, with attention paid to the combination of nitrogen, phosphorus and potassium. Apply carbon dioxide gas fertilizer to meet the needs of photosynthesis. Pay attention to spray multi-element micro-fertilizer and potassium-calcium foliar fertilizer in the result period of tomato, once in 10-15 days, even spray 2-3 times.
4. Properly dense planting, appropriate sparse planting, timely pruning, improve ventilation and light transmission conditions.
5. Strengthen greenhouse management. Into the result period, the temperature control during the day is 20-25°C, generally not exceeding 28°C, and keeping 15-17°C at night. Improve lighting conditions and increase greenhouse light transmission. Watering in a timely manner to prevent flood irrigation, timely release of moisture after each watering, the best use of submerged membrane irrigation or drip irrigation, water infiltration after a timely cultivator, to prevent soil compaction, and promote good root development.
6. Potassium citrate and sugar were sprayed on the foliage after onset to increase C/N.
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