The branch of the Rosselkhoztsentr in the Komi Republic warns of the danger of the spread of annular bacterial rot of potatoes. This is a dangerous disease that can destroy up to 45% of the crop, so it is very important to take timely measures when the first signs appear.
The causative agent of the disease is a harmful bacterium of the species Corynebacterium sepedonicum (Clavibacter michiganensis subsp. Sepedonicum).
The disease affects leaves, stems, stolons and tubers. The wilting of plants begins to appear during the flowering period and continues until the end of the growing season. Not all can wither on a potato bush, but only 1-2 stems. On the cut of the stem, yellowing or darkening of the vessels is visible.
In dry weather, diseased plants wither quickly, tubers are less infected in appearance, due to the latent nature of the infection, and in wet years with moderate temperatures, the plant withers slowly, while the damage to the tubers increases.
On tubers, the disease manifests itself as ring and pit rot. With ring rot, necrosis of the vessels of the ring is observed, when squeezed, a yellow mucous exudate appears. With pitted rot, creamy oily spots are formed under the skin of the tuber, which increase in size during storage.
Diseased tubers are the main source of infection.
The pathogen does not hibernate in soil, but it can persist on plant debris.
The disease spreads during harvesting: bacteria are easily transmitted through knives when cutting tubers, with mechanical damage from agricultural implements.
The most accurate method for diagnosing ring rot is to perform a polymer chain reaction (PCR) test.
Basic control measures
There are no chemicals available to combat ring rot.
• Healthy planting material
• Compliance with crop rotation.
• Cultivation of resistant varieties.
• Removal of diseased plants during the growing season
• Warming up the seed for 2-3 weeks at a temperature of 14-18 degrees before storage or at the end of the storage period in order to identify diseased tubers.
• Timely mowing and haulm removal.
• Thorough preparation and disinfection of potato storages before laying tubers.