Lethal decline of Phoenix canariensis in Texas (US)
During 2001, a lethal decline of Phoenix canariensis was observed in the county of Nueces, Texas (US). Symptoms were characterized by adventitious roots, inflorescence necrosis, progressive browning and desiccation of younger leaves, and finally general decline of the tree. In infected plantings, not all palms were necessarily affected by the disease. These symptoms are very similar to those previously observed on P. canariensis and P. dactylifera in the Brownsville and Lower Rio Grande Valley in Southern Texas during the late 1970s. Supported by epidemiological observations (host range, scattered pattern of dissemination, rate of spread), the disease was considered at that time to be lethal yellowing. It can be recalled that lethal yellowing was observed on palm trees in Southern Florida and widespread at that period, although today this disease is no longer active. Studies were done to identify the causal agent of the current lethal decline of P. canariensis in Texas. Phytoplasmas belonging to the coconut lethal yellowing* (16SrIV) group were found in diseased palms. These phytoplamas were distinct from the lethal yellowing agent described in Florida, but were most closely related to (if not identical) to the Carludovica palmata yellows agent, which is a phytoplasma described from declining C. palmata trees (Cyclanthaceae) in Yucatan, Mexico.
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*Coconut lethal yellowing phytoplasma is listed as an EPPO A1 quarantine pest.
Sources
Harrison, N.A.; Womack, M.; Carpio, M.L. (2002) Detection and characterization of a lethal yellowing (16SrIV) group phytoplasma in Canary island date palms affected by lethal decline in Texas.
Phytopathology, 86(6), 676-681.