Lethal Bronzing (also known as Texas Phoenix Palm Decline) is caused by Phytoplasma palmae (a mollicute similar to bacteria, but lacking a cell wall) that is closely related to Palm Lethal Yellowing . Lethal Bronzing was first described in 1980 in Texas, and first reported in Hillsborough County, FL in 2006. Since 2006, it has spread throughout Florida, mostly around the central part of the state. The specific vector of Lethal Bronzing is unknown. Lethal Bronzing is most likely vectored by piercing-sucking insects that are known to spread phytoplasmas to plants. Phytoplasmas infect the phloem, the vascular tissue that moves carbohydrates from leaves to the roots.
As its former name implies, Lethal Bronzing infects Phoenix species. In Texas, the disease was reported to kill Phoenix canariensis (Canary Island date palm) and P. dactylifera (date palm) in as little as 4 months. Currently there are 10 confirmed hosts of Lethal Bronzing. In Florida, host range includes Phoenix sylvestris (Sylvester palm), P. canariensis, P. dactylifera, P. roebelinii (pygmy date palm), Sabal palmetto (sabal palm), Syagrus romanzoffiana (queen palm), Adonidia merrillii (Christmas palm), Bismarckia nobilis (Bismark palm), Livistona chinensis (Chinese fan palm), and Carpentaria acuminata (Carpentaria palm) (Bahder, 2017).
You can read our full study on Lethal Bronzing/Texas Phoenix Palm Decline and treatments here: TPPD Study
Symptoms include fruit drop, necrosis of inflorescence, bronzing of lower foliage which progresses upward, subsequent spear leaf collapse and death.
We recommend a two-part treatment of IMA-jet or AzaSol to deal with the leaf hopper and Arbor-OTC to deal with the phytoplasma every 120 days. This method provide excellent protection on our studies held in 2017.
Treat every 120 days for best results.
Photos credit of University of Florida IFAS Extension