Abstract
A description is provided for Peronospora rumicis. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Emex spinosa, Polygonum convolvulus, Rumex acetosa, R. acetosella, R. alpestris (= R. arifolius), R. auriculatus, R. aviculare, R. hastatus, R. lunaria, R. longifolius, R. montanus, R. patienta, R. polyanthemus, R. repens, R. scutatus, R. thyrsifolius, R. tuberosus, R. vesicarius. DISEASE: Downy mildew of Rumex. Both leaves and flowers are infected. On R. acetosella, the plant remains upright following infection and the upper leaves crumple. In other Rumex species, infected leaves become covered in a very dense layer of violet-coloured felt on their undersurface, whereas a grey felt layer develops on flowers. Leaves become yellowish and their margins roll back (39, 159). GEOGRAPHICAL DISTRIBUTION: Africa: Libya, Morocco, South Africa. Asia-Temperate: Azerbaijan, Republic of Georgia, Israel, Kazakhstan, Kirghizistan, Stavropol. Asia-Tropical: India. Australasia: New Zealand. Europe: Austria, Cyprus, Czechoslovakia, Denmark, Eire, Estonia, Faeroes, Finland, France, Germany, Hungary, Italy, Latvia, Norway, Poland, Romania, Russia (Novgorod, St. Petersburg, Smolensk, Yaroslavl), Serbia, Sweden, Switzerland, Ukraine, UK (England, Scotland), Yugoslavia. TRANSMISSION: By conidia which are dispersed by wind or rain-splash. Mycelium perennates in the root.