Beet necrotic yellow vein virus (BNYVV) is a plant virus, transmitted by the plasmodiophorid Polymyxa betae. The BNYVV is a member of the genus Benyvirus and is responsible for rhizomania, a disease of sugar beet (Rhizo: root; Mania: madness) that causes proliferation of thin rootlets, and leads to a smaller tap root with reduced sugar content. Infected plants are less able to take up water, and wilting can be observed during the warm period of the year. If the infection spreads to the whole plant, vein yellowing, necrosis and yellow spots appear on the leaves, giving the virus its name. Hosts and symptoms BNYVV Infects all of the following species: Beta vulgaris (beetroot), Beta vulgaris var. cicla, Beta vulgaris var. rubra, Beta vulgaris var. saccharifera (sugarbeet), Chamomilla recutita (common chamomile), Chenopodium (Goosefoot), Chenopodium quinoa (quinoa), Cichorium intybus (chicory), Cirsium arvense (creeping thistle), Convolvulus arvensis (bindweed), Datura stramonium (jimsonweed), Descurainia sophia (flixweed), Heliotropium europaeum (common heliotrope), Nicotiana tabacum (tobacco), Plantago major (broad-leaved plantain), Raphanus raphanistrum (wild radish), Spinacia oleracea (spinach), Tetragonia tetragonioides (New Zealand spinach), Tribulus terrestris (puncture vine), Veronica hederifolia and Xanthium strumarium (common cocklebur). The plants that suffer infections from BNYVV in the most abundance are all the subspecies of Beta Vulgaris, specifically Beta vulgaris var. saccharifera (sugar beet), and Spinacia oleracea (spinach). In Beta vulgaria var. saccharifera (sugar beet), symptoms are most often local in the roots and leaves, but can be found systemically on rare occasions. Symptoms are seen differently depending on when the infection occurs in the plant. In early life stages and early growing season, a diseases called rhizomania is caused as a result of the virus. Rhizomania is the growth of fine, hairy secondary roots which are dead and thus prevent the proper uptake of water. Because of rhizomania, the sugar beet is subject to severe infection where the entire plant is stunted, leaves are wilted, and death can occur. Due to the severity of an early onset infection, the most common symptom of BNYVV, yellow mosaic on the leaves, is rarely seen as the plant often dies before the virus can spread. For midseason and less severe infections, rhizomania results in the storage root rotting and constricting, causing the root to swell near the crown. In this case, rhizomania doesn't cause the plant to die which allows the virus is able to make its way to the leaves resulting in yellow-pale discoloration, proliferation,