Palm Phytoplasmas in Florida and the Caribbean Basin

Until 2006, the only phytoplasma disease documented on palms in Florida was lethal yellowing (LY), caused by subgroup 16SrIV-A. LY is widespread in the Caribbean Basin, including the Yucatan peninsula of Mexico. While Cocos nucifera L. is the primary palm affected by LY, there are over 30 documented palm hosts, including Phoenix spp. A disease with similar symptoms on Phoenix spp. was documented in Corpus Christi, Texas in 2000. The pathogen was identified as subgroup 16SrIV-D. It is presumed that this phytoplasma was the cause of a lethal decline on Phoenix spp. in the Rio Grande Valley of Texas in the 1970s. In 2006, this phytoplasma (16SrIV-D) was detected in declining Phoenix spp. in west central Florida. During subsequent surveys of declining palms in this area, a third phytoplasma, subgroup 16SR-IVF, was documented in a limited number of declining palms, but has not been detected since that time. In 2008, numerous Sabal palmetto (Walter) Lodd. ex Schult. & Schult. f. with symptoms typical of lethal yellowing-type disease was observed in west central Florida.  It was determined that subgroup 16SrIV-D was the cause of the observed symptoms. This discovery was the first time a phytoplasma disease had been documented on a palm native to Florida, even in the areas historically affected by lethal yellowing (16SrIV-A). Subsequently, subgroups 16SrIV-A and 16Sr-IVD have been documented in native palms in the Yucatan peninsula, coastal Texas and Puerto Rico.