Since 2004, containerized nursery stocks of rosemary and lavender have been affected by a collar and root rot problem in Valencia (Spain). Nurseries had about 70% of affected plants showing lack of vigour, wilt and dieback symptoms. Phytophthora sp. was isolated consistently from symptomatic plants, and eighteen isolates were obtained, ten from lavender and eight from rosemary. The species was identified as P nicotianae based on morphological and physiological features. Some isolates were identified as atypical representatives of P. nicotianae. Identification of the isolates was confirmed by the sequence of the nuclear ribosomal internal transcribed spacer (ITS) region. Both morphological characters and DNA analysis supported the species identification for all the isolates. Pathogenicity tests were carried out and Koch's postulates were fulfilled.