Reaction of potato cultivars to primary and secondary infection by potato mop‐top furovirus and strategies for virus detection¹

Abstract

Potato cultivars in elite seed production in Finland were tested for susceptibility to primary and secondary infection by potato mop‐top furovirus (PMTV) in field and pot experiments during 1987 and 1988. The tubers of all 22 cultivars tested became infected under favourable conditions in naturally infested soil, and most of them showed external and internal spraing symptoms when stored first at 18°C for 2 weeks and then 2 weeks at 8°C. The second incubation cycle increased the percentage of tubers manifesting symptoms and the halving of tubers also favoured symptom development. The cultivars most tolerant to primary infection were Pito, Hertha and Record, and the most susceptible were Sabina, Olympia, Saturna and Matilda. The same cultivars, excluding Saturna, were also the most susceptible to secondary infection, which decreased tuber yield up to 37%. The virus could be detected fairly reliably in soils by the bait‐plant method, and in the tubers after a repeated cycle of incubation at 18 and 8°C. Electron microscopy and serological methods are useful in both virus detection and identification but they still have severe limitations.