Palm diseases in north and central Florida
- Ganoderma, the rare but dreaded butt rot of palms
- Fusarium, a new disease of queen palms
- How to disinfect pruning tools
- Bud rot
Ganoderma
the dreaded "butt rot" of palms
This palm has been killed by Ganoderma. Note the conks on the lower trunk in this photo and the photo below
Ganoderma, caused by the fungus Ganoderma zonatum, is an infrequent but devastating palm problem. If your palm gets Ganoderma, it will die and you will not be able to safely plant another palm in that location in your landscape. Researchers are not sure how palms become infected. They believe the fungus is transmitted through wounds to the roots made during transplanting, wounds to the lower trunk when pruning off boots, spike wounds made by climbing with spikes or even possibly wounds from continued weed whacker damage at the
The fruiting bodies found on the lower trunk of a dying or dead palm confirm the disease, Ganoderma.
Ganoderma zonatum is in the same family as decay fungi that cause internal decay in hardwood trees (Ganoderma applanatum and Ganoderma lucidum) but it is not the same pathogen and will not affect hardwood trees. The disease decays the lower 4 or 5 feet of the palm trunk. It is soil borne but not a root disease. All palms are susceptible to Ganoderma infection.
The symptoms are progressive leaf death from the bottom of the crown. Finally the newest frond, the spear, dies. Often, but not always, a fruiting body (a conk) appears somewhere in the lower part of the trunk. This conk allows for easy confirmation of the disease. This fruiting body drops millions of spores that can infect other palms.
This palm is infected with Ganoderma. The lower fronds are gradually dying and the center spear, the newest leaf, is smaller. Conks (shown in the next photo below) were found on the lower trunk
So it is a good idea to remove the conks as soon as they appear. And then remove the dead or dying tree as soon as possible. The lower part of the trunk should be placed in a landfill and not used for mulch. The upper part of the infected palm can be used for mulch.
For a complete brochure on Ganoderma in palms prepared by University of Florida researchers Dr. Monica Elliott and Dr. Timothy Broschat, click here. That article can be downloaded from the site as a PDF file.
View of a young, fresh fruiting body on the lower trunk of a dying palm
Fusarium
a new disease of queen palms and Washingtonian palms
A queen palm killed by fusarium wilt fungus looks like it has been freeze dried. Affected fronds do not droop.
There is a new disease of queen palms (Syagrus romanzoffiana) that is moving into the northeast Florida. It was first discovered in 2003 in south Florida and has also infected Mexican fan palm (Washingtonian robusta). It is a fusarium fungus that kills the affected palm. Within two to three months of infection, the leaves become desiccated. Curiously, the leaves remain erect and do not droop down around the trunk.The affected queen palm has a freeze dried look.
There is no known cure. Little is still known about how the disease is spread. We believe the primary mode is through infected pruning tools. But there have also been cases when clean (sterilized) pruning tools have been used and these pruned palms have also become infected.
It can be difficult to distinguish between fusarium wilt death and cold damage on queen palms. The above tree was damaged and possibly killed by extended temperatures in the mid-20’s in north Florida.
We therefore believe there could be wind transmission of fusarium spores to freshly cut frond stubs. Therefore only dead fronds should be pruned so no freshly exposed vascular tissue that is susceptible to infection will be left exposed after pruning. That is why it is extremely important take special precautions about who prunes your queen palms and Washingtonian palms, how they prune and how they disinfect their pruning saws.
Hand pruning saws are best because they are easier to disinfect. Chain saws should not be used to prune fronds from queen palms and Washingtonian palms because chain saws cannot be properly disinfected. And again only dead leaves should be removed. According to Don Hodel, Cooperative Extension Environmental Horticulturist Los Angeles County, "Unpruned trees never have Fusarium or Thielaviopsis diseases. Prevention through sanitation and more conservative leaf pruning and trunk skinning is the only way to control these diseases."
The question has been asked, "Can you replant a queen palm in the same location where a palm died of fusarium wilt?" Keep in mind that fusarium is a soil-borne pathogen and there can be spores in the soil that may reinfect new queen palms and Washingtonian palms. So for now until more information is available, we do not recommend replanting a queen palm or Washingtonian palm in the same location.
How to Disinfect Palm Pruning Tools
Use one of the four following methods:
Bleach: use a 1 part household bleach to 3 parts water. Soak the tools for at least 5 minutes and then spray with WD-40 to help prevent corrosion
Pine-sol brand cleaner: use 1 part Pine-sol and 3 parts water. Soak for at least 5 minutes.
Alcohol: use 1 part alcohol and 1 part water (Either rubbing alcohol or denatured ethanol can be used). Soak for at least 5 minutes.
Butane torch: heat up the saw blade with the flame
Chain saws cannot be properly disinfected. It is best to have two or three hand saws so the saw or saws not being used can be soaking in the disinfectant solution while the other saw is being used.
