Synchytrium endobioticum is an A2 pest for many regions, and details of its biology, distribution and economic importance can be found in the EPPO Global Database. In the EPPO National Regulatory Control System for S. endobioticum (Standard PM 9/5) no inspection procedures are considered for the pathogen on potatoes as such, because the wart disease regulations of most countries subject any plot known to be wart-infested to long-term official control and prohibit the growing of potatoes on it. In addition, many countries allow only cultivars resistant to the pathotype(s) present to be grown in a surrounding zone (‘safety zone’ or ‘buffer zone’). Exported potatoes, plants with roots, flower bulbs and tubers should come from a plot in which S. endobioticum has never occurred, or else from a plot found free from S. endobioticum.
There is a presumption that resting spores of S. endobioticum survive on the plot. The soil test, combined with the interval since the previous infection, may be used as a criterion for complete or partial descheduling of that plot; complete descheduling removes all official limitation on the types of crops that may be grown, whereas partial descheduling removes only some of the limitations on use and allows the growing of ware potatoes resistant to the pathotype(s) present. Caution should be applied when growing resistant cultivars after partial descheduling in case of possible breakdown of resistance.
A plot that has been infested with S. endobioticum and has been kept under official control with limitations on the crops allowed to be grown may be descheduled either completely or partially, depending on the interval since the last symptoms of the disease and on the results of soil tests.
Descheduling relates to the entirety of the plot that was originally scheduled. However, for partial descheduling there may be conditions in which a subunit of the plot may be considered separately, provided that the NPPO can guarantee the phytosanitary security of the subplot.
Photo: EPPO (2024) EPPO Global Database. https://gd.eppo.int
Reference: PM 3/59 (3) Synchytrium endobioticum: descheduling of previously infested plots. EPPO Bulletin, 47: 366–368. https://doi.org/10.1111/epp.12409
