Susceptibility to <i>Phytophthora cinnamomi</i> of the commonest morphotypes of Holm oak in southern Spain

Abstract

Summary The four main morphotypes of Holm oak ( Quercus ilex subsp. ballota ) present in Andalusia ( expansa , macrocarpa, microcarpa and rotundifolia ) were infected with Phytophthora cinnamomi to determine their susceptibility to the root pathogen. No large differences were found among the four morphotypes in the infection of roots, which always showed a high degree of necrosis. However, the different responses of the foliage to infection separated the four morphotypes of Holm oak into three groups: very susceptible ( microcarpa ), susceptible ( expansa ) and moderately susceptible ( rotundifolia and macrocarpa ). The natural hybrid Q. ilex ballota – Q. faginea exhibited a low level of root and foliar symptoms when infected with P. cinnamomi . Quercus faginea could be considered as a source of resistance to P. cinnamomi in future breeding programmes.