Lethal Bronzing Disease

Lethal bronzing disease was discovered in Florida in 2006 and is caused by a phytoplasma; a type of bacteria that lacks a cell wall. Some may remember a similar disease also caused by phytoplasma that was prevalent in 2007, lethal yellowing (LY). “In 1969 LY appeared in Key Largo and in late 1971several trees in Coral Gables were diagnosed as having LY. Within months the disease had killed a thousand trees in Miami.” “In Key West, 75% of the coconut palms were destroyed.”  The LB phytoplasma is similar but genetically distinct from the phytoplasma that causes lethal yellowing.

Royal Green has seen increasing positive samples over the last 2 years, we were dealing with it first in Vero Beach and it has made its way down the coast; Fort Pierce then Jensen and Stuart. Over the last 8 months or so we have picked up positive samples moving south and as far west as I95 in St Lucie, Palm City, Stuart and now Hobe Sound.

LBD is transmitted by a planthopper, Halpaxius crudus. This plant pest injects the bacteria through their saliva when feeding on the sap from the palm’s foliage. Once a tree is infected with LB there is no cure; the palm needs to be removed. The only treatments for these phytoplasma diseases are preventative injections of the antibiotic oxytetracycline. The injections are done on a quarterly basis.

“Lethal yellowing has eliminated nearly all of the ‘Jamaica Tall’ coconut palms in Dade County, but some plantings of ‘Jamaica Tall’ had escaped the disease by 1981. Broward County has also lost most of its original coconut palms. Palm Beach County, largely because of the success of antibiotic injection programs, had lost only 35-40% of their coconut palms by 1981.”

Most recently Sugar palm has been added to the susceptible host list according to Dr. Bahder.

We have had great results with the antibiotic injection program. There are currently 16 palms on the susceptible list for LB

Scientific Name Common Name
Adonidia merrillii Christmas Palm
Bismarckia nobilis Bismarck Palm
Butia capitata Pindo Palm
Carpentaria acuminata Carpentaria Palm
Cocos nucifera Coconut Palm
Livistona chinensis Chinese Fan Palm
Phoenix canariensis Canary Island Date Palm
Phoenix dactylifera Edible Date Palm
Phoenix roebelinii Pygmy Date Palm
Phoenix sylvestris Wild Date Palm
Pritchardia pacifica Fiji Fan Palm
Pseudophoenix sargentii Buccaneer Palm
Sabal Mexicana Mexican Palmetto
Sabal palmetto Cabbage Palm
Syagrus romanzoffiana Queen Palm
Trachycarpus fortunei Chinese Windmill Palm