These phytosanitary measures were successful until 1973 when pathotype 2 was detected for the first time. In 1991, pathotype 1 was detected in the south-eastern part of the country. So far, only pathotypes 1 and 2 have been found in the Netherlands. At present, results of intensive surveys have showed that S. endobioticum occurs in two areas. Strict phytosanitary measures are being applied, in particular to prevent any further spread.
Galls appear on all underground parts except the roots.
Buds on stems, stolons, and tubers are the centers of infection which results in abnormal growth leading to production of warts. Warts are subject to decay. Entire tubers may be entirely replaced by the warty proliferation. Strict phytosanitary methods are required for prevention of spread to clean areas.