Palm Diseases in Central Florida: Lethal Bronzing, Ganoderma and Bud Rot

When a palm in Polk County is dying and it is not a nutrient problem or cold damage, it is usually one of three diseases. Two cannot be cured and one can sometimes be caught. The important thing is to identify which it is quickly, because two of them also spread to other palms on the property and the neighborhood.

Lethal bronzing

Lethal bronzing is a bacterial disease spread by a small planthopper insect, and it has been moving through Central Florida for years. It kills sabal palms, queen palms, date palms and several others.

• What it looks like: the oldest, lowest fronds turn a distinctive bronze or reddish-brown, not yellow, and the discoloration moves up the crown. On a fruiting palm, the fruit drops early. The spear frond dies last, and once it goes the palm is finished. The whole process takes a few months.
• Can it be treated? Not once symptoms appear. A palm showing lethal bronzing cannot be saved and should be removed promptly to reduce the population of the insect carrying it. Healthy, high-value palms nearby can be protected with regular antibiotic trunk injections, which is a preventive program rather than a cure, and it has to continue as long as the disease is in the area.

Ganoderma butt rot

Ganoderma is a fungus that rots the base of the trunk from the inside. It lives in the soil and enters through wounds and roots.

• What it looks like: a general decline, wilting and browning of older fronds, slowed growth, and eventually a hard shelf-like growth called a conk on the lower trunk, white when young and brown on top when mature. By the time the conk appears the trunk is substantially rotted.
• Can it be treated? No. There is no cure, and a palm with Ganoderma is a falling hazard because the base is hollow. It should be removed, and the stump ground out and the soil removed, because the fungus stays in the stump and the soil. Do not plant another palm in the same spot.

Bud rot

Bud rot is a fungal or bacterial infection of the growing point at the center of the crown, and it often follows cold damage or a period of wet weather. It is the one that can sometimes be caught.

• What it looks like: the spear frond, the newest one at the center, turns brown or black and pulls out easily with a foul smell at the base. The older fronds may stay green for a while, which is misleading; the palm is dying from the center out.
• Can it be treated? Sometimes, if caught very early. Removing the rotted tissue and applying a fungicide into the crown occasionally saves the palm, and a palm that pushes a new spear afterward has survived. Once the bud is fully rotted the palm cannot regrow and has to come out. Our post on frost damage covers the cold-damage version.

What it usually is not

Yellowing on older fronds, frizzled new growth and yellow banding are nutrient deficiencies, extremely common in our sandy soil, and fixable with the right feed. Our palm fertilizer guide covers them. Regular lawn fertilizer near a palm makes them worse. A palm that has been over-trimmed, with fronds removed above horizontal, is also stressed and more susceptible to everything above; our trimming guide explains why.

Preventing spread

• Remove diseased palms promptly, and grind and remove Ganoderma stumps.
• Clean pruning tools between palms. Ganoderma and other pathogens move on saws.
• Do not wound trunks with mowers, trimmers or climbing spikes.
• Feed correctly so palms are not stressed, and do not over-trim.
• Consider preventive injections for valuable palms where lethal bronzing is active.

What we do

We diagnose declining palms, remove those that cannot be saved, and maintain the rest. Request a visit and we will tell you which of these you are looking at, or see our tree and palm services.