Influence of water source on frequency of Phytophthora occurrence was the purpose of this study. Phytophthora spp. was detected in 3 rivers, 2 canals and 2 ponds. Rivers were situated in different part of Poland. Two of them (Jasieniec and Pisia) is following through horticulture areas, whereas Wisła - through area with hardy ornamental nursery stocks. Water canals and ponds are situated nearly or in nursery. Rhododendron leaves baits cv. ‘Nova Zembla' were used for detec-tion Phytophthora in water from March to November. Number of necrotic spots on baiting leaves was the measure of population density of Phytophthora in water. Phytophthora spp. were detected from water from March to November. In canals, the most of necrotic spots on baiting leaves were observed in May and June. In rivers Jasieniec and Rawka and water ponds significantly more necrotic spots on baiting leaves were noticed in March, April, May and in September, October and November. P. cirticola was recovered as the most often occurring species and next P. cryptogea, P. cinnamomi, P. citrophthora, P. taxon Salixsoil.
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Occurrence of Phytophthora spp. in Polish rivers and pathogenicity of iso-lates toward some plants were studied. Rivers Jasieniec, Pisia and Rawka were surveyed during all the year with one month interval. First 2 rivers are situated in horticultural areas in Warsaw and Łódź districts whereas the third one is running through agricultural fields and forests. Rhododendron leaves were used as the baits for detection of Phytophthora from water. Number of necrotic spots on baiting leaves was a measure of population densities of Phytophthora spp. in rivers. The occurrence of Phytophthora in water was noticed during all year with the lower density in the 3rd quarter of the year. Five Phytophthora species and taxon Salixsoil were identified among isolates recovered from 3 rivers. During all year from 3 surveyed rivers (except from Pisia in the first quarter) P. citricola was recovered as the most often occurring species. Additionally P. cactorum, P. cambivora, P. cinnamomi and P. megasperma were detected from rivers. In laboratory trials water isolates of P. cactorum and P. citricola colonized roots, stem parts and leaves of birch with the significantly faster spread of necroses on plant parts inoculated by P. citricola. In greenhouse trial both species caused root ...
Pathogenicity of Phytophthora isolates obtained from water reservoirs and watercourses toward Ligustrum vulgare, Chamaecyparis lawsoniana, Lavandula angustifolia and Rhododendron sp. was evaluated. Tested isolates were detected form 3 water ponds situated in ornamental nurseries, 3 rivers and drainage canal in nursery. All of analysed isolates of P. citrophthora and P. cinnamomi colonized tested plant tissues in the laboratory and greenhouse conditions. There were no dif-ferences in pathogenicity of isolates from host plants in comparison to cultures from different water sources.
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The purpose of that article was to show the significance of water as the source of plant pathogens, and need of it effective disinfection methods in modern agriculture and horticulture. The increase in the cost of agricultural water use for crop irrigation and the necessity of using the same water several times, as well as the changing climatic conditions, including prolonged shortage of atmospheric precipitation and often extreme temperatures during the summer, necessitate the selection of an effective, easy to apply and economical method of disinfecting recirculated water to eliminate or minimize the occurrence of the most serious plant pathogens inhabiting various water sources. Among them, microorganisms of the genera Phytophthora, Pythium and Fusarium, and the species Rhizoctonia solani, Verticillium dahliae and some pathogenic bacteria pose the most serious threat. Some of them can be found in rivers, streams, ponds and water reservoirs, others are soil-borne pathogens that cause root and stem base rot of many plant species. The available literature describes at least a dozen methods of water disinfection, among them slow filtration through sand or lava filters, chlorination and heating. The literature data indicates that the use of sand filters is the most effective, safe and cheapest ...
