Water as the source of Phytophthora spp. in ornamental nurseries

Abstract

Rhododendron leaf baits were used for detection of Phytophthora spp. from water and as the measure of population density of that group of pa-thogens in rivers and nursery reservoirs. Phytophthora species, mainly P. citricola, were detected both from all sources of water. Significantly more necrotic spots were noticed on baits held in Skierniewka and Zwierzynka rivers than in Ner. Significantly more colonies were recovered from river water in July than in August and September. In nursery reservoirs more necrotic spots on leaves were observed in August in comparison to July and September. Using of pond water for sprinkling of Thuja occidentalis and Buxus sempervirens resulted in the development of Phytophthora tip blight of thuja and stem rot of boxwood. P. citricola was isolated from diseased parts of plants.