Change in the regulatory status of Verticillium wilt of hop in UK
In the past, Verticillium albo-atrum (EPPO A2 organism) attacking hop in UK was considered to occur in two distinct groups of strains, the more severe "progressive" strains occurring only in South-East England, while the "fluctuating" or "mild" strains occurred also in the west Midlands hop-growing area. This is reflected in the A2 quarantine pest status agreed by EPPO. Growers who suspected that progressive wilt was present on their land were required to notify the authorities and to destroy suspect plants. The authorities could, if necessary, apply eradicatory measures, destroying the hop plants and grassing over the area. Only healthy planting material was permitted to be moved. Movement of used hop poles and picking machinery was also restricted. In areas where progressive wilt did not occur, only susceptible hop cultivars were permitted to be grown (so that outbreaks could easily be detected).
By the Plant Health (Great Britain) (Amendment) order 1991, many of these measures are removed. It is recognized that there is continuous variation in aggressiveness in the fungus, and that this exists in all hop-growing areas in England. Accordingly, the eradicative measures and restrictions on cultivars have been withdrawn. However, the regulations on healthy planting material, and on movement of used hop poles and picking machinery, are retained. Hop growers are required to keep detailed records of all new plantings of hops.
Sources
Plant Health Division, MAFF (1992-01)