Lethal bronzing in Polk County palms
A disease that's been in Florida since 2006 is killing sabals and queen palms across Polk County. There's no cure for a palm that has it. Here's how to recognize it, what to do, and how to protect the palms next to it.
What it is
Lethal bronzing — formerly 'Texas Phoenix palm decline' — is caused by a phytoplasma, a bacterium without a cell wall that lives in the palm's vascular tissue and plugs it. It's carried from palm to palm by the American palm cixiid, a small planthopper (Haplaxius crudus) that feeds on palm fronds and breeds in the grass underneath. It was first found in Florida in Hillsborough County in 2006 and has spread to more than thirty counties, with Polk squarely in the zone. It kills sabal (cabbage) palms — Florida's state tree — queen palms, all the Phoenix date palms (Canary Island, edible date, pygmy date, sylvester), pindo palms and coconuts. It does not affect foxtails, Bismarcks, Chinese fan palms or royal palms, as far as is known.
How to recognize it
- Fruit and flowers drop early — often the first sign, easy to miss.
- The oldest, lowest fronds turn bronze-brown — not yellow — from the tips inward, and it moves up the crown fast, over weeks.
- The spear leaf dies. The newest, still-closed frond at the center of the crown turns brown and can be pulled out by hand. Once the spear is dead, the palm is dead; it may take a few months for the rest of the crown to collapse.
The look-alikes: potassium or magnesium deficiency, common in Polk's sandy soils, yellows the oldest fronds slowly from the bottom with the spear staying green — fixable with the right palm fertilizer. Ganoderma butt rot shows a shelf fungus at the base of the trunk. Fusarium wilt on queens and Canary Island dates kills one side of each frond first. A lab test through UF/IFAS confirms lethal bronzing, but by the time the spear is dead the answer is the same.
What to do with an infected palm
Remove it, quickly. There's no cure for a symptomatic palm, and every week it stands it's a feeding station for planthoppers that carry the phytoplasma to the next palm. Have it taken down in sections, hauled off the property (not chipped and left as mulch), and the stump ground. Then look hard at every susceptible palm within a few hundred feet.
Protecting the healthy palms
- OTC trunk injections. Oxytetracycline HCl injected into the trunk by a licensed applicator protects a healthy palm as long as the injections continue — every three to four months, indefinitely. $50–$100 per palm per treatment. Worth it for a prized date palm or a row of mature sabals; not practical for a whole subdivision.
- Don't inject a symptomatic palm. It won't recover, and the injections just delay the removal.
- Manage the grass. The planthopper breeds in turf under palms; keeping St. Augustine mowed and away from the trunk helps a little.
- Clean tools. Sanitize pruning saws between palms. The disease spreads by insect, but it's one less risk.
- Replant smart. Replace a lost sabal or queen with a species the disease doesn't hit — foxtail, Bismarck, Chinese fan, royal in frost-free spots — unless your HOA requires a specific palm.
Common questions
Can lethal bronzing be cured?
No. Once a palm shows symptoms, it will die. The injections are preventive only — they protect healthy palms and have to be repeated every three to four months.
How fast does it spread?
Palm to palm by planthopper, so it moves through a neighborhood over a few seasons rather than overnight. Removing infected palms quickly slows it; leaving them standing speeds it up.
Is my sabal palm's bronzing really the disease?
If the lowest fronds are bronze (not yellow), it's moving up fast, and the spear leaf is dead or dying — yes, almost certainly. Slow yellowing with a live spear is a nutrient problem. Send a photo and we'll tell you which; a UF/IFAS lab test confirms it.
Should I inject the palms next door?
If they're susceptible species and you want to keep them, yes — through a licensed applicator, on a schedule. We can refer one. It's a real cost; for a single prized date palm it's an easy call, for a row of queens most owners replace instead.
Will my HOA make me replace the palm?
Many Polk HOAs require a replacement tree or palm. We give you the removal receipt and the arborist's note on the disease, and we'd suggest a resistant species for the replacement.
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