How to Manage Pests

Pests in Gardens and Landscapes

Seasonal development and life cycle—Bacterial ring rot

The bacterial ring rot bacterium overwinters in infected tubers. It does not live freely in the soil, but it can survive for several years as dried slime on equipment or potato sacks. The bacterium is highly contagious. It infects tubers through wounds that reach into the vascular ring. Seed cutting is the principal means of spreading.

The ring rot bacterium is a vascular parasite and moves up in the water-conducting tissues and produces toxins that cause foliar symptoms. Rosetting and other early symptoms of dwarfing occur when bacteria proliferate in very young stems of certain varieties. About half to three-fourths of the daughter tubers of an infected plant will be infected with the ring rot bacteria, but may not develop symptoms. Ring rot develops in tubers most rapidly at 64° to 75° F and only slightly at 37° F.

Rosetting of foliage
Rosetting of foliage

Statewide IPM Program, Agriculture and Natural Resources, University of California
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