UF/IFAS Extension Palm Beach County banner

Lethal Bronzing: A Destructive New Palm Disease

 

Lethal Bronzingpreviously called Texas Phoenix Palm Decline, is a relatively new bacterial disease (called a phytoplasma) that is causing significant palm losses in Palm Beach County.  Symptoms are similar to lethal yellowing, but affect a much smaller number of palm species.  The damaged vascular system of the palm leads to wilting, and eventually death.  University of Florida research is determining which sap feeding insect(s) may spread it.  Affected species include Sabal (Cabbage), Queen, Pygmy Date and other Phoenix species, Christmas, Bismarck, Chinese Fan and Carpentaria palms.

Symptoms

Older fronds die first and may be reddish-brown, dark-brown or grayish depending upon which species is affected, and stage of infection.  Symptoms can sometimes be confused with nutrient deficiencies like potassium, or Fusarium wilt.  Flower spikes may die prematurely, and fruit may drop off prematurely.

Lethal bronzing symptoms on sabal palm. Photo: UF/IFAS Schall

What Can You Do?

The disease is confirmed by laboratory analysis of tissue extracted from the trunk.  Remove and dispose of infected symptomatic palms.  Administer antibiotic injections to non-symptomatic susceptible species growing around removed palms.  Inject oxytetracycline at 3 grams per palm (1 gram for Christmas palm).  It is not known if the oxytetracycline will help susceptible palm species already showing symptoms.  However, once the palm spear leaf dies, the palm will die even if lower fronds are still green.

Additional information and photos can be found in the UF publication Texas Phoenix Palm Decline.

20 Comments on “Lethal Bronzing: A Destructive New Palm Disease

  1. Dear Bill, I read with interest and concern your article on TPPD, LB (phytoplasma) that is affecting so many types of palms. Up here in Northern Florida, the species you mentioned are all an important part of our cold hardy palm flora. Has it been seen in Northern Florida, and how would you prevent it from getting into a collection of palms? It seems that every day I see trucks loaded with palms heading north on I 95. Quarantine? Inspection? Also, being a veterinarian, I have access to oxytetracycline. Could you describe the device and technique for injecting a palm tree. I imagine that my 3 cc syringes with 20 gauge needles will not work, Thank you. John Rossi DVM MA

    • Dr. Rossi:

      Keeping lethal bronzing out of a palm collection would involve being diligent in looking for the problem. It may be that the disease has not been identified in your county yet. A late 2017 assessment by the Division of Plant Industry of submitted lab samples indicated the disease was from the Hillsborough to Volusia County corridor south. North of that, it has been identified in Levy, Alachua, Duval and Bay Counties in Florida. Once you have the disease on your property, immediately surrounding susceptible palm species should be treated with the oxytetracycline about every three months. Three of the commercial systems that are available are Tree Saver, Arborsystems and Mauget. All have websites where you can get a better look at the equipment. The Mauget system is self-contained, and therefore may end up being more affordable since you will not have to purchase the fairly expensive application equipment used with the other systems. Nozzel Nolen recently did a YouTube video on how they do it at: https://www.youtube.com/watch?v=tLMIyhf2Pw8 …Currently, some developers in Palm Beach County are beginning to ask for susceptible palm species to be tested prior to installation. Taking specimens does injure the trunk though. As far as I know, there is not an effort to quarantine areas that have the problem. It is known to occur all the way from the Yucatan through Texas and the Gulf Coast states and into Florida, so it is quite widespread.

  2. I have a beautiful triple Alexander Palm, but I fear it has fallen victim to the lethal bronzing. It appears two of the trunks have dead leaf spears. The third appears to still be healthy. If I cut the two dead trunks, do you think I can salvage the third and keep it healthy, or would cutting the two harm the third one? Thank you for any information or advice you can provide.

    • Alexander palms (Ptychosperma elegans) are not currently thought to be susceptible to either lethal bronzing or lethal yellowing. Die back is due to some other factor(s). Are you seeing any conks on the lower trunks. These are fan-like growth that indicate a fungal Ganoderma problem. If this is the problem, removing the dead trunks will not help. Can you email some pictures of the problem to me at bschall@pbcgov.org ? – Bill

  3. The Sable and Phoenix palms are dying on massive numbers here in Palmetto fl. Seems like from northern Hillsborough to southern manatee the disease is getting outta control. And eastward through Lakeland. I drive a lots and am always saddened by the loss of the Sables. Seems like counties/ state doing nothing about it. Non of the dead dying ones are ever cut down. I see all these new developments putting in Sylvester palms they are always toast within 6 months. What a waste of money, plant something resistant please. Southern Pinellas county including st pete are getting destroyed by this disease too. I’ve seen a lot of queens palms with the disease too, although if taken care of in my experience they have more resistance then palmetto and Sylvester’s. The state planted Sylvester’s in northern manatee on I 75 Hillsborough by i4 and 275 in st pete. I’d say 90 pct of them are dead in 2 years. Why is state planting expensive susceptible palms then not removing them when dead and unsightly ? Plant royals yes the can get killed by the cold but least don’t catch and spread the disease further.

    • Hi Jeff:

      Yes, the disease was first spotted in your general area of the state in 2006. As you are indicating, thousands of palms have already been lost to lethal bronzing since then. We expect the number of affected species list will be expanded now that the disease has moved into Miami-Dade County where we find Florida’s greatest variety of palms. Below, as of July 2019, is a list of the palm species currently known to get the disease:
      Christmas Palm, Bismarck Palm, Pindo Palm, Carpentaria Palm, Coconut Palm, Chinese Fan Palm, Canary Island Date Palm, Edible Date Palm (Phoenix dactylifera), Pygmy Date Palm, Wild Date Palm (Phoenix sylvestris), Fiji Fan Palm, Buccaneer Palm, Mexican Palmetto (Sabal mexicana), Cabbage (Sabal) Palm, Queen Palm and Chinese Windmill Palm (Trachycarpus fortunei).

  4. Now in Martin County as well. I just lost my Canary Date Palm to this disease this week.

    • Hi Ms. Forster. Yes, lethal bronzing definitely affects Canary Island date palms. Loss of those vary large majestic palms is quite sad.

    • Hi Mr. Miller. No, currently Washingtonia palms are not believed to be affected by either lethal bronzing, or another similar palm disease, lethal yellowing.

  5. just let nature takes its course i have grown three coconut tress form seed they have surviveid white fly funguse etc stop messing with nature if they die it is meant to be STOP adding genictic cures which just screws up the balance of nature thats why all these infections happen man has none this to many chemicals to nature just let it go

    • Thanks Ms. Delucantonio for your comments. The problem, of course is that the disease was not here in Florida originally. It is believed to have arrived in 2006 from offshore, possibly via infected insect vectors (carriers) blown here by Hurricane Wilma in 2016. Also, remember that this disease kills our native sabal (cabbage) palms which covers all of Florida and up into the southeastern United States. If we lose many of those, it will have a huge impact on the Florida environment and the landscapes around our homes and businesses. The current treatment is not a genetically modified product, but antibiotics. Hopefully additional research will help us come up with additional, simpler ways to keep this very destructive disease from destroying sabal and about 15 other currently known palm species.

  6. Just to make sure I understand. Treat a healthy palm one time with 3 grams of oxytetracycline, or do I need some sort of maintenance program for a healthy palm?
    What about a smaller multiple or Robalini palm, same 3 grams?

    • Hi Eric:

      The 3 gram treatment needs to be repeated every 3 months. If you use the same hole, be sure to drill it a little deeper before the second 3 month treatment. For following three month treatments, drill another hole. Just how long to continue is a judgement call. Typically once you start, it needs to be continued. The 1 gram rate is for smaller palms like adonidia or Phoenix roebelenii (pygmy date palm). It makes sense to use less for the smaller palms. The rate would be per trunk. For example, if the P. roebelenii or the adonidia are triples, then each trunk would need to be treated with 1 gram of OTC for 3 grams total.

  7. We have an older (70 years) sable palm in Pinellas County(Indian Rocks Beach ) that we think may be dying due to Lethal Bronzing disease. Could you give us detailed instructions on how to get a sample. How to store the sample. A family member works at U of F, can she drop off the sample on Hull road? Thank you for any information. I am sad to see this tree that I grew up with dying.

  8. Hello, Bill. Thank you so much for your service. Above, Jeff wrote about the frequent death of Sylvester palms. I had one installed in January, and have noted the browning of fronds. I don’t know if some browning is normal or not. I have fertilized and applied Epsom salts. I would appreciate any incite.
    Mary

    • Hanks Ms Kelley:

      I received your email and photo and will take a look and respond to you directly via that email.

Leave a Reply

Your email address will not be published. Required fields are marked *