Poinsettia Leaf Curl, a New Disease Caused by a Geminivirus

A serious disorder of unknown aetiology was found on the poinsettia cv. Angelica, a recent introduction to Taiwan. The symptoms of downward leaf curling and vein enation were similar to those of leaf curl disease on tobacco. The causal agent of the disease was transmitted to healthy plants of ʹAngelicaʹ poinsettia, common poinsettia and tobacco by whiteflies. Twinned particles measuring 16-18x30-32 nm were detected in a purified preparation obtained from diseased leaf tissues of "Angelicaʹ poinsettia, indicating that the disease is caused by a geminivirus. An earlier introduction of common poinsettias also showed mild leaf curl symptoms under natural condition. When the causal agent of this disease was transmitted to healthy ʹAngelicaʹ poinsettia plants by whiteflies or bud grafting, these plants also developed severe leaf curl symptoms, indicating that the disease is not a new introduction to Taiwan.