Response of Quercus ilex seedlings to Phytophthora spp. root infection in a soil infestation test

Phytophthora species are the main agents associated with oak (Quercus spp.) decline, together with the changing environmental conditions and the intensive land use. The aim of this study was to evaluate the susceptibility of Quercus ilex to the inoculation with eight Phytophthora species. Seven to eight month old Q. ilex seedlings grown from acorns, obtained from two Spanish origins, were inoculated with P. cinnamomi, P. cryptogea, P. gonapodyides, P. megasperma, P. nicotianae, P. plurivora, P. psychrophila and P. quercina. All Phytophthora inoculated seedlings showed decline and symptoms including small dark necrotic root lesions, root cankers, and loss of fine roots and tap root. The most aggressive species were P. cinnamomi, P. cryptogea, P. gonapodyides, P. plurivora and P. psychrophila followed by P. megasperma., while Phytophthora quercina and P. nicotianae were the less aggressive species. Results obtained confirm that these Phytophthora species could constituted a threat to Q. ilex ecosystems and the implications are further discussed.