What are the control methods for potato ring rot?

Ring rot is caused by the bacterium Corynebacterium sepedonicum (potato ring rot corynebacterium). It can occur on stems and leaves as well as on tubers, and can continue to cause damage during storage, causing tuber rot in severe cases. In recent years, with the promotion and application of virus-free seed potatoes, the occurrence of ring rot has decreased significantly.

1. Symptoms

Ring rot is also a vascular bundle disease. Aboveground symptoms generally appear after the flowering stage. Initial symptoms appear on the lower leaves of the plant, showing chlorosis between the veins, appearing mottled, and wilting occurs. Afterwards, the areas between the veins gradually turn yellow and dry up, and the leaf margins turn yellow and curl upward. Because environmental conditions and variety resistance differ, the symptoms shown by plants also differ. One type of symptom is plant dwarfing, thinness, few branches, small and yellowing leaves, with inconspicuous wilting symptoms, and it generally appears only in the late growth stage; the other is acute wilting of the plant, with leaves turning grayish green and curling inward, dying prematurely, and the vascular bundle ring at the stem base changing color, and in severe cases bacterial fluid can be squeezed out.

The typical symptom of infected tubers is discoloration along the vascular bundle ring on the cross-section, and rot in severe cases. In the early stage of the disease, no symptoms can be seen on the tuber surface. As the disease progresses, the skin color darkens or turns brown, and in severe cases bacterial fluid overflows from the cross-section.

2. Control methods

Integrated measures are mainly adopted for control. Establish disease-free seed propagation bases and use virus-free pre-elite seed potatoes for seed potato propagation; plant whole tubers to eliminate the spread of bacteria through cut pieces; sprout tubers before planting and promptly eliminate diseased seed potatoes.