Judit Sárándi-Kovács, László Nagy, Ferenc Lakatos and György Sipos
During a regular survey of declining forests in 2011, sudden dieback symptoms were observed on scattered wild cherry trees (Prunus avium) in a mixed deciduous forest stand, located in the flood plain area of the Rába River, in northwest Hungary. In this study, we correlated both soil conditions and presence of Phytophthora spp. to dieback of cherry trees. Two Phytophthora species, P. polonica and P. plurivora, were isolated from the rhizosphere soil of the dying trees. By contrast, only P. polonica was recovered from the necrotic tissues of symptomatic roots. Stem and root inoculation tests on cherry seedlings showed pathogenicity of both species, although P. polonica proved to be more virulent. This is the first report of natural infections of P. polonica.
Judit Sárándi-Kovács, Ilona Szabó and Ferenc Lakatos
This paper reports on a two-year monitoring of Phytophthora species occurring in the catchment area of the Rák Brook near Sopron. P. gonapodyides, P. lacustris, P. plurivora and P. pseudosyringae were found in the course of surveys completed in the vegetation period of 2011 and 2012. Diversity profiles and cluster analysis were calculated in order to compare the Phytophthora communities detected at different sites and times. Seasonal differences were observed in the species compositions. Temperature data and basic hydrological parameters were found to determine the presence or absence of waterborne Phytophthora species in the catchment area of the Rák Brook. Pathogenicity of the Phytophthora species discovered was confirmed and evaluated against sessile oak seedlings.
Judit Sárándi-Kovács, Ferenc Lakatos and Ilona Szabó
This paper reports on the current situation of the Phytophthora species occurring in a declining common alder (Alnus glutinosa) stand in North-West Hungary. The stand was affected by a severe epidemic caused by Phytophthora alni in the late 1990s. The authors evaluated the health condition of the forest stand and collected soil samples from the rhizosphere of twenty selected trees two times per year in 2011 and in 2012 in order to isolate Phytophthora species. A diverse Phytophthora community was found in the soil consisting of eight species with different aggressiveness and with different ecological demands. Pathogenicity tests confirmed the role of the collected strains in the decline of the alder stand.
The paper reports on the occurrence and impact of Phytophthora species in a declining eastern black walnut (Juglans nigra) stand in West Hungary. The health condition of the trees was investigated and soil samples were taken from the rhizosphere of the trees two times per year in 2011 and 2012 in order to isolate Phytophthora species. Altogether 20 trees were selected for investigations. The species identity of the isolates was determined by morphological and molecular methods. Phytophthora cactorum and Phytophthora plurivora were found as supposedly responsible for the decline of the trees. The abundance of the two species was changing at the different sampling times, presumably due to the different weather conditions. The intraspecific diversity of both species was estimated based on the ITS1-5.8S-ITS2 sequences of the isolates.