How to prevent and control greenhouse tomato stem rot

Tomato stem rot is actually a very serious disease that affects the growth and yield of tomatoes. So how can we better prevent it?

1 Main pathogens and causes

Tomato stem rot is mainly caused by the combined infection of pythium and bacteria. It is a soil-borne disease. It is most likely to occur when flooding is carried out and the ground temperature is too high. The main reasons are: ① The soil was not disinfected or disinfected incompletely before planting. The soil in the greenhouse is planted with solanaceous and melon vegetables for consecutive years, resulting in the coexistence of multiple pathogens in the soil, and the disease will occur immediately once the conditions are suitable. ② The planting period of greenhouse tomatoes overwintering is too early, the ground temperature is too high during the seedling stage, and after flooding, the permeability of the root system is reduced, so that the pathogens in the soil multiply and reproduce in large numbers under suitable temperature and moisture conditions, and infect the vascular bundle at the base of the stem, making the plant susceptible to disease. ③ The weak growth of tomato plants also gives soil-borne diseases an opportunity to take advantage. ④ Other reasons, such as a heavy rain after the tomato seedlings have recovered, the rain directly soaked the tomato seedlings, and the failure to drain and spray pesticides in time after the heavy rain led to the disease.

2 Main prevention and control measures

① One month before planting, clean up the dead branches and leaves inside and outside the greenhouse and transport them out of the greenhouse for destruction, cover the greenhouse film tightly, and keep the greenhouse hot from August to September. At the same time, deep plow the soil in the greenhouse, combine watering 667 square meters with 20-30 kg of quick-acting nitrogen fertilizer or spread broad-spectrum fungicides such as carbendazim and thiophanate-methyl, and then cover the ground with film to kill most of the pathogens in the soil.

② The planting period of overwintering greenhouse tomatoes should not be advanced blindly, and attention should be paid to covering the ground film late. The suitable planting period for overwintering greenhouse tomatoes should be from late September to early October, and all regions should plant them in time according to actual conditions.

③ Strengthen cultivation management. Avoid flooding with water. If the ground temperature is too high, dig up the soil at the base of the stem to dry it in the sun. After planting and acclimatization, combine the prevention and treatment of viral diseases with spraying of Apollo 963, Sterling, Plant Power 2003 and other agents to improve the disease resistance of the plants, so as to achieve prevention as the main measure.

Once the tomato plants show symptoms, such as leaf wilting, slow growth, and blackening of the surface of the stem base, apply 500 times diluted Rhizome Protect and Carbuncle to the affected part; when peeling off the side of the stem and finding that the vascular bundle has turned yellow and the leaves are severely wilted, irrigate the roots with 500 times diluted Rhizome Protect and Apollo to promote the development of new roots; when the leaves turn yellow, spray with 500 times diluted Carbuncle or 100 times diluted Apollo 963, or irrigate the roots with 500 times diluted Benomyl and Fusarium frost; plants whose vascular bundles turn black and brown should be removed immediately, and the soil should be disinfected to prevent the spread of pathogens with watering.