First record of Phytophthora cinnamomi on cork and holm oaks in France andevidence of pathogenicity

In 1995 and 1996, a survey for the presence of Phytophthora cinnamomi in co rk and helm oak sites in southeastern France was carried out. Twenty-four s ites were chosen. Tree decline severity and other characteristics were asse ssed. Subplots of four trees were more fully investigated: relative soil wa ter content was assessed and Phytophthora isolation was attempted from soil samples. When cortical lesions were observed, isolations were carried out from infected tissues. In six cork oak and one halm oak sites, P. cinnamomi was isolated from soil or trunks. All the different isolates obtained in 1 995 were aggressive on cork and helm oaks. However, these species were less susceptible than Castanea sativa and more susceptible than Q. rubra. These results confirm the pathogenicity of P. cinnamomi towards Mediterranean oa ks and its possible involvement in the decline process of these species. (C ) Inra/Elsevier, Paris.