Bacterial ring rot of potato caused by Clavibacter sepedonicus: Asuccessful example of defeating the enemy under international regulations.

Abstract

BackgroundBacterial ring rot of potato (Solanum tuberosum) caused by the gram‐positive coryneform bacterium Clavibacter sepedonicus is an important quarantine disease threatening the potato industry around the globe. Since its original description in 1906 in Germany, management of ring rot has been a major problem due to the seedborne nature (via seed tubers not true seeds) of the pathogen allowing the bacterium to be transmitted long distances via infected tubers.Disease symptomsOn growing potato plants: interveinal chlorosis on leaflets leading to necrotic areas and systemic wilt. On infected tubers: vascular tissues become yellowish brown with a cheesy texture due to bacterial colonization and decay.Host rangePotato is the main host of the pathogen, but natural infection also occurs on eggplant, tomato, and sugar beet.Taxonomic status of the pathogenClass: Actinobacteria; Order: Actinomycetales; Family: Microbacteriaceae; Genus: Clavibacter; Species: Clavibacter sepedonicus (Spieckermann and Kotthoff 1914) Li et al. 2018.Synonyms (nonpreferred scientific names) Aplanobacter sepedonicus; Bacterium sepedonicum; Corynebacterium sepedonicum; Corynebacterium michiganense pv. sepedonicum; Clavibacter michiganensis subsp. sepedonicus.Microbiological propertiesGram‐positive, club‐shaped cells with creamy to yellowish‐cream colonies for which the optimal growth temperature is 20–23°C.DistributionAsia (China, Japan, Kazakhstan, Nepal, North Korea, Pakistan, South Korea, Uzbekistan, the Asian part of Russia), Europe (Belarus, Bulgaria, Czech Republic, Estonia, Finland, Georgia, Germany, Greece, Hungary, Latvia, Lithuania, Norway, Poland, Romania, European part of Russia, Slovakia, Spain, Sweden, Turkey, Ukraine), and North America (Canada, Mexico, USA).Phytosanitary categorizationCORBSE: EPPO A2 list no. 51. EU; Annex designation I/A2.