Susceptibility of potato cultivars to Synchytrium endobioticum
Studies have been carried out in United Kingdom to compare the laboratory and field reaction of a range of potato cultivars to infection with Synchytrium endobioticum (EPPO A2 quarantine pest). A range of resistant (RG1), less resistant* (RG2) and susceptible cultivars (S) has been used. It was found that the degree of susceptibility observed in laboratory tests is well correlated with the reaction of cultivars in field tests. The study was also designed to assess the extent of winter spore production in RG2 cultivars, as this can be of interest to the control of the pathogen and its eradication on infested sites. The author observed that the RG2 cultivars studied (cvs Mona Lisa, Pentland Crown, Red Craigs Royal, Pentland Kappa and Ausonia) produced winter spores in the field test. 10 % of the winter spores obtained from cv. Ausonia germinated in distilled water. Compost from the field plot was estimated to contain 14-18 apparently viable spores/g, and this resulted in 100;% infection of the highly susceptible cultivar Arran Chief when grown on the plot. For descheduling procedures, the author felt that in order to avoid any risk of rejuvenating infection in sites previously found infested, only resistant cultivars (RG1) should be selected. The author also pointed that the spore counts which have been suggested as a criteria for descheduling land are not reliable, as the results obtained in this study demonstrate the need to deschedule only the land in which no apparently viable spores are recovered.
* Less resistant cultivars show intermediate reaction and may produce winter spores in laboratory tests but no wart tissue in the field. And it was felt that these cultivars may represent a hazard if grown on infected sites, as they could contribute to the development of new races and could rejuvenate an ageing spore population.
Sources
Browning, I.A. (1995) A comparison of laboratory and field reactions of a range of potato cultivars to infection with Synchytrium endobioticum (Schilb.) Perc.
Potato Research, 38 (3), 281-289.