New Report of Phytophthora occultans Associated with Root and crown Rot on Sansevieria

In the summer of 2022, sansevieria plants with symptoms of root and crown rots were detected in greenhouses of Isfahan province, Iran. Symptomatic tissues of the root were cultured on CMA-PARPH. Recovered oomycete isolates were purified by single-zoospore technique on WA. The baiting method using citrus leaf disc was also used to isolate Phytophthora spp. isolates from the soil around roots. Four isolates were obtained directly from infected root tissues and two isolates from soil. Fungal isolates were identified based on morphological characteristics and molecular data of β-tubulin (βtub) and translation elongation factor 1-alpha gene (tef1-α) genes. According to the morphological and phylogenetic analysis, all isolates were recognized as Phytophthora occultans. Koch's postulates were completed and confirmed that Phytophthora occultans isolates were responsible for sansevieria root and crown rots. To our knowledge, this is the first report that Phytophthora occultans associated with root rot of sansevieria in Iran and probably in the world.