Relationship between source of water, occurrence, and pathogenicity of Phytophthora plurivora

Abstract

Phytophthora plurivora was the most often detected species from water using rhododendron baits. The species was isolated from water of two rivers, Jasieniec and Korabiewka, a water pond and a drainage canal from March to November, 2008 (in Korabiewka river also in December). The highest population density of P. plurivora was observed in March and April in water pond and canal, and in May in both analysed rivers. In laboratory trials all tested isolates colonized rhododendron and poplar leaves. Isolates from drainage canal were the most pathogenic for rhododendron. Isolates detected in March from water pond and two rivers caused the quickest spread of necrosis on leaf blades. On poplar leaves the fastest development of necrotic spots was observed when isolates obtained in June and November were used for inoculation, while the isolate from September sample was less pathogenic.