New host plants for development of Phytophthora cryptogea in Poland

Pathogenicity of nine isolates of Phytophthora cryptogea from different host plants was tested. In the laboratory trials, all cultures (except S. arachnoideum) colonized leaf blades and stem parts of 3 alstroemeria cultivars, but isolates from Anthurium andreanum, Aquilegia discolor and Alstroemeria × hybrida were the most pathogenic. In the tests with columbine the quickest spread of necrosis was observed on leaves inoculated with P. cryptogea from A. discolor and Gerbera jamesonii, whereas the slowest when isolates from Sempervivum arachnoideum was used. Inoculation of S. arachnoideum with eight isolates of P. cryptogea caused necrosis of leaves, but isolates from A. discolor, Campanula persicifolia and S. arach-noideum were the most pathogenic