Root diseases caused by Phytophthora or Pythium spp. have not been common in the Okanagan-Similkameen in recent years. These diseases are typically sporadic, usually occurring on single vines that are excessively irrigated.
A root rot caused by the fungus Roesleria subterranea has also occurred sporadically in Okanagan vineyards. It is considered to be a weak root pathogen that colonizes injured or dead roots, from where it may also invade healthy roots.
During a 2007-2009 survey of grapevine decline problems, conducted by Agriculture and Agri-Food Canada (O'Gorman, Haag & Sholberg), roesleria root rot was found in several vineyards in vines that were also infected with Cylindrocarpon.
Affected vines are smaller than nearby healthy plants, and the foliage may become chlorotic or colour prematurely. A canker develops near the soil line and usually extends downward to the roots.
Removal of the periderm exposes the necrotic woody tissue underneath. Roots may become blackened and decayed, and smaller fibrous roots may die. Death of the vines may occur within two years from the time symptoms appear.
