Fusarium oxysporum strains from wilting potato plants : Potential causal agents of dry rot disease in potato tubers

The present study focused on the isolation, identification and assessment of the dry rot-causing ability of Fusarium spp. associated with potato wilt in the Middle Volga region of Russia. A total of 14 Fusaria were isolated from the root necks of wilting potato plants. One isolate was identified as Fusarium solani, while the remaining thirteen of the isolates related to the species Fusarium oxysporum. Artificial inoculation of potato tubers with fungal spores showed that tubers of the cultivar Reggi exhibited the highest resistance [cultivar resistance index (CRI) = 0.78] to the tested isolates, while susceptibility (CRI = -0.44) was registered in tubers of the Zhukovskij rannij cultivar. The manifestation of dry rot during artificial inoculation with the spores of vascular-associated Fusaria was significantly influenced by pathogen virulence [H (9, N = 300) = 60.630, p <0.000001] and plant cultivar type [H (2, N = 210) = 17.201, p =0.00018]. However, not all isolates inhabiting occluded vessels caused dry rot in tubers.