Lethal bronzing and lethal yellowing of palms: what the extension services record
What the University of Florida IFAS publications and Texas A&M AgriLife Extension say about the two phytoplasma diseases of palms: the pathogens, the planthopper that carries lethal yellowing, the symptom order, the palm species and Florida counties named, and the regulated status in Texas.
Checked against the sources at the bottom of this page on October 9, 2026. Rules, fees and pay change: the source has the last word.
This page reports what the official source says. It is not legal advice: ask the office named here. It describes what the named sources say, is not a diagnosis of any palm and does not say what should be done with one. Each section names its source, all read on October 9, 2026. The full list of diseases is on the tree diseases page.
Two diseases, two phytoplasmas
The University of Florida IFAS publication on lethal yellowing (PP-222/PP146, Bahder and Helmick) says the disease is caused by a phytoplasma, a type of bacterium that lacks a cell wall and cannot be cultured in the laboratory, and gives the proposed name Candidatus Phytoplasma palmae. The IFAS publication on lethal bronzing (PP243/PP163, Bahder and Helmick) says lethal bronzing used to be called Texas Phoenix Palm Decline, and that its phytoplasma, Candidatus Phytoplasma aculeata, is similar to but genetically distinct from the lethal yellowing one. Both publications say the pathogens live in the phloem of the palm and are not known to survive outside a plant or insect.
| Point | Lethal yellowing | Lethal bronzing |
|---|---|---|
| Florida records the publication gives | Florida landscapes in the southern one-third of the state; observed in Sarasota and Manatee Counties in 2007 and Indian River County in 2012. | Hillsborough County, Florida, in late 2006; the same pathogen was found on Canary Island date palm in Texas in the early 2000s, hence the first name. |
| How it moves | By the planthopper Haplaxius crudus, a piercing and sucking insect that feeds on phloem. | By piercing-sucking insects; the publication names planthoppers and leafhoppers as the main groups. It says the disease cannot be mechanically transmitted, for example by pruning tools. |
| Palm species recorded | At least 37 palm species documented. | 21 palm species, with a table of coyol, Christmas, Bismarck, pindo, coconut, Canary Island date and others. |
| Places named | Southern Florida, with the planthopper confirmed as far north as Gainesville. | 36 Florida counties, Jacksonville the northernmost limit and the Florida Keys the southernmost record; also Louisiana. |
Symptoms as the publications describe them
Both publications give the same early order. The lethal yellowing publication says the first obvious symptom on mature palms is premature drop of most or all fruits, followed by inflorescence necrosis, with the emerging flower spikes partly or wholly blackened. It says these only show if the palm is flowering or fruiting when the disease develops. For tall coconuts the next symptom is yellowing starting with the oldest leaves, but it says foliar discoloration varies markedly among cultivars and genera, and that no single symptom is diagnostic: the appearance and order of symptoms together identify the disease. It notes that boron deficiency also causes premature nut drop in coconut, without the water-soaked, discolored calyx end.
The lethal bronzing publication gives premature fruit drop or necrotic inflorescences as the first symptoms, then discoloration of the oldest leaves moving up to younger ones, ending with collapse of the spear leaf, which it says means the bud (apical meristem) has died. It gives a latent period of about four to five months from infection to symptoms, about two to three months from symptoms to spear collapse though highly variable, and says that in some cases no leaf discoloration shows but the spear leaf collapses and the palm tests positive.
Status in Texas
Texas A&M AgriLife Extension says lethal bronzing is the only known phytoplasma disease of palms in Texas and that it is a reportable, regulated condition although it can kill palm trees within a year. Its factsheet page says the publication covers recognising infected palms, quarantine rules for moving palms from affected counties and management in landscapes and nurseries. The page does not list the counties or the rule wording; the office to ask is the Texas A&M AgriLife Extension county office linked from its page. The Florida publications name no regulation and no report line.
What the sources say about management
Both Florida publications describe management measures for affected and healthy palms. This page gives no treatment steps, product names, rates or timings. Another palm pest with its own page is red palm weevil.