First report of Phytophthora nicotianae causing avocado root rot in Thailand

Abstract

Plantations of avocado (Persea americana), a high-demand crop in Thailand are severely affected by Phytophthora spp. A severe avocado root rot disease of avocado that has recently been observed in the Chiang Dao district of Chiang Mai province causes dieback and root rot. A potential pathogen isolated from symptomatic plant material was identified as P. nicotianae based on morphology and ITS and COX1 sequences. Pathogenicity assay on detached leaves and seedling roots confirmed the pathogenicity of P. nicotianae. The report is the first of P. nicotianae causing avocado root rot in Thailand.