Why is bacterial pith necrosis of tomato so prone to occur?

Bacterial pith necrosis is an important disease in the process of tomato cultivation, seriously affecting the yield and quality of tomatoes. Sometimes it can even cause the entire greenhouse to have no harvest at all. Why is bacterial pith necrosis so prone to occur? Let's take a look together below.

1. Environmental factors

High humidity is a basic condition for the occurrence of bacterial pith necrosis in tomatoes. When tomatoes grown in protected facilities in winter encounter consecutive cloudy days and cannot be ventilated normally, or during a period after watering, the humidity in the greenhouse becomes very high, creating conditions for the occurrence of the disease.

2. Wound infection

Bacterial pith necrosis of tomato mainly infects through wounds on the stems. Many farmers do not pay attention to the external environment when carrying out farming operations. When they perform pruning and side-shoot removal on consecutive cloudy days or after watering, the wounds produced provide a channel for the infection of the pathogen.

3. Spindly plants with excessive vegetative growth develop severe disease

Spindly plants have a high water content in their stems. On the one hand, this is not conducive to wound healing and makes it easier for the pathogen to invade; on the other hand, it facilitates the spread and development of the pathogen in the pith, making it fast.

Symptom manifestations

Bacterial pith necrosis of tomato is a systemic infection disease, mainly affecting stems, branches, leaves and fruit, and mostly occurring during the fruiting period;

In the early stage of the disease, young leaves fade green, and in severe cases the upper part of the plant fades green and wilts;

Along with necrosis of the lower stem, brown to dark brown spots appear on the surface of the diseased stem, and the exterior becomes hard. When the diseased stem is cut longitudinally, the pith can be seen to turn black or show necrosis;

It shrinks and becomes hollow, the vascular bundles turn brown, and adventitious roots may form at the sites where lesions occur in the pith;

In production, when the lower stem is infected, it often causes the death of the whole plant;

When humidity is high, bacterial ooze overflows from stem wounds and adventitious roots, which is different from bacterial canker.

Control measures

Plant at a reasonable density, strengthen ventilation, and reduce humidity in the greenhouse, especially during consecutive cloudy weather or just after watering.

Avoid carrying out operations such as pruning and side-shoot removal during consecutive cloudy weather or just after watering when the humidity in the greenhouse is high, so as to reduce wounds on the stems. After routine pruning and leaf removal, spray bacterial agents in time.

Strengthen management and avoid excessive vegetative growth of the plants, especially when the plant stems are about 40 cm, fertilizer and water should be properly controlled, particularly reducing the amount of nitrogen fertilizer.

After discovering that tomatoes are infected, it is necessary to promptly spray Wanjia 500 times solution + Yiwei 750 times solution for root drenching treatment.