Sepedonicus Bacterial ring rot is a recurring disease problem in temperate regions.
It occasionally appears in tropical countries when seed from temperate regions is used, and can be confused with brown rot.

Symptoms of Ring Rot potatoes disease

Symptoms usually appear mid-season or later and include wilting (often of only some stems of a plant). Lower leaves become flaccid, with a pale yellow color between major veins. An upward rolling of leaf margins may occur, and death may soon follow.
Stem and tuber sections show brown vascular rings that, when squeezed, may exude bacterial ooze. Most of the tuber vascular ring rots and turns either gray, yellowish, tan, or reddish brown. However, secondary organisms may cause a soft rot. Tuber infection can be confused with bacterial wilt (or brown rot), except that oozing around the eyes does not occur.
Ring rot is mainly a seed tuber-transmitted disease. It survives in volunteer potato plants. The bacterium does not survive in the soil but may be carried on tools, machinery, crates, and bags.

Management

Plant only disease-free seed. Eliminate volunteers in the field before planting clean stock. Follow strict sanitation practices and disinfest bins, equipment, tools, and crates. Use new bags. Plant entire (not cut) seed tubers.

Riptide 6 Week Pest Control

Lower leaves usually wilt first, are slightly rolled at the margins, and are paler green than healthy leaves. As wilting progresses, leaf tissues between veins become yellow. In the later stages of disease, margins of lower leaves die and become brittle and eventually entire stems yellow and die.

Ring rot potato tuber Symptoms

The first sign of ring rot in tubers is the appearance of a light, creamy-yellow to brown discoloration of the vascular ring at the stem end. When the freshly cut tuber is squeezed, a creamy-yellow or light brown exudates (scrud) will appear.

In more advanced stages, the entire vascular ring will rot with cavities extending to the center of the tuber.
The outer surface of such tubers will sometimes be cracked and depressed. Secondary soft rot bacteria may invade these tubers.

The only way bacteria persist under field conditions is in plant debris and cull tubers.

Therefore, disease loss due to residual bacteria in the soil will be minimal if plant and tuber debris is destroyed during the winter or rotational period.

Certified or foundation seed has a zero tolerance for ring rot potato disease. Therefore, any significant amount of ring rot must originate from home grown seed, contaminated equipment or storage facilities, or volunteer plants in the field.