Isolation and pathogenicity ofPhytophthoraspecies from sessile oak (Quercus petraea(Matt.) Liebl.) stands in Slovakia

During the monitoring of oak decline phenomenon in Slovakia, symptoms indicative ofPhytophthoradiseases were observed in sessile oak stands in western Slovakia. The study aimed to test the presence and diversity ofPhytophthoraspecies associated with declining oak stands. From rhizosphere soil samples,Phytophthora plurivora,P. quercinaandPythium intermediumwere detected. Soil inoculation tests withP. plurivoraandP. quercinaon 1-year-old oak plants inflicted damage to the root system, and significant differences in measured root parameters between the inoculated and control treatments after 5 months. Although more wilting symptoms were observed inP. plurivora-infected seedlings (7 out of 12 inoculated seedlings),P. quercinacaused the highest amount of damage to root systems, and for example, fine root length was 1.6 times shorter compared to the control. To our knowledge, this is the first report ofP. plurivoraandP. quercinain sessile oak stands in Slovakia.