Drought has been assumed as a predisposing factor in the decline caused by Phytophthora cinnamomi on Mediterranean Quercus forests, enhancing cork oak susceptibility to the root infection. However, P. cinnamomi outbreaks appear associated to waterlogged soils, with infections being particularly successful when soil moisture content fluctuates from flooding to water deficiency. We obtained cork oak seedlings potentially predisposed to Phytophthora disease by exposing them to a short (3 weeks) or a long (6 weeks) drought. These seedlings subjected to drought, together with well-watered seedlings, were exposed to two different soil concentrations of P. cinnamomi inoculum (chlamydospores) and submitted to high soil humidity for 4 weeks. Values of root necrosis were significantly higher in inoculated oak seedlings compared to non-inoculated control seedlings, but no significant differences were observed depending on previous drought treatments. Consequently, drought cannot be considered as a predisposing factor required for Phytophthora root disease development in cork oaks; although the adverse effects of both factors (drought and Phytophthora root infections) likely have synergistic consequences in the decline and death of affected oaks.

干旱被认为是造成地中海栎林上疫霉菌引起的衰退的诱因，这增加了软木对根部感染的敏感性。然而，P。cinnamomi暴发似乎与涝渍的土壤有关，当土壤水分从洪水到缺水波动时，感染特别成功。通过使它们经受短时间（3周）或长时间（6周）的干旱，我们获得了可能引起疫霉病的软木橡树幼苗。这些遭受干旱的幼苗与浇水良好的幼苗一起暴露于两种不同浓度的肉桂对虾接种（衣原体）并在高土壤湿度下放置4周。与未接种的对照幼苗相比，接种的橡树幼苗的根部坏死值显着更高，但是根据之前的干旱处理，未观察到明显的差异。因此，干旱不能被认为是软木栎疫霉根病发展所必需的诱发因素。尽管这两个因素（干旱和疫霉根部感染）的不利影响都可能对受影响的橡树的衰退和死亡产生协同影响。