Phytophthora pseudosyringae associated with a severe disease of Nothofagus obliqua in Chile
During the last 30 years, dieback, partial defoliation, and mortality of Nothofagus obliqua and N. alpina have been observed in Chile, between the Biobío and Los Lagos regions. Although the cause of this disease is unknown, symptoms observed resembled those caused by Phytophthora spp. on other tree species. Studies have been conducted in the Nahuelbuta coastal range (Biobío region) to determine Phytophthora species associated with dieback symptoms and mortality of N. obliqua trees. Samples (bark, wood, soil) were collected in March 2013 in a pure stand of N. obliqua trees which were showing partial defoliation and bleeding cankers. In this stand, approximately 10% of the trees were severely defoliated, with dead twigs and many trees displayed stem cankers. A Phytophthora species was isolated from stem cankers and soil samples, and all isolates were identified as Phytophthora pseudosyringae. In inoculation experiments, it was found that these isolates were also pathogenic to N. alpina and N. dombeyi. The similarity between the symptoms observed on Nothofagus spp. over the past 30 years in Southern Chilean regions and the symptoms observed on N. obliqua in the Nahuelbuta coastal range indicates that Phytophthora spp. have the potential to damage Nothofagus spp. It is concluded that more studies are needed to determine the extent and impact of P. pseudosyringae on Nothofagus spp. in Chilean forests.
Sources
Fajardo SN, Valenzuela S, Dos Santos AF, González MP, Sanfuentes EA (2017) Phytophthora pseudosyringae associated with the mortality of Nothofagus obliqua in a pure stand in central-southern Chile. Forest Pathology e12361. https://doi.org/10.1111/efp.12361