Getting to the root of that palm tree rot | Sally Scalera
Due to the ever-growing popularity of palms throughout Brevard County, I thought it would be a good idea to share a previous article. Some landscapes have a few palms and then other yards are filled with all different types of palms. For anyone growing palms, it is important to learn about the disease called Ganoderma butt rot. The fungus that causes the disease is distributed throughout the states of Florida, Georgia, and South Carolina.
All palms, as well as cycads, are susceptible to Ganoderma butt rot, a fatal disease with no known cure. It is easily spread by wind-blown spores, dirty shovels containing contaminated soil, etc. The fungal genus Ganoderma is a group of wood-decaying fungi that are found throughout the world on all types of wood, including conifers, hardwood, and softwood trees, plus palms.
There are many different species of this fungus, but only one species is a pathogen of palms in Florida. That fungus is Ganoderma zonatum. The conk is the most easily identifiable structure associated with the fungus. When the conk starts forming on the trunk or stump, it is a solid white mass that is relatively soft when touched. The “white button” is the beginning stage of the conk. As the conk matures, a small shelf or bracket will start to appear. Eventually, a very distinct shelf-like structure will form that is quite hard, with a reddish-brown top surface and a white underside. A mature conk will have distinct zones, hence the species name zonatum.
The primary symptom typically observed is the wilting of the fronds, which can range from mild to severe. The typical appearance of a palm that has been killed by Ganoderma is for all the fronds to hang down around the trunk. It is possible for the palm to die before a conk is ever produced, as well as for the palm to produce a conk before it even shows symptoms. The presence of the conk is a clear sign of the fungus. A palm should be removed as soon as possible when a conk appears on the trunk. The fungus degrades the lignin in the lower four to five feet of the palm trunk. This is not a soft rot so the trunk will still be very hard. If a palm dies, with all the fronds hanging down, without the presence of a conk, remove it from the landscape but leave the stump. Watch the stump for the appearance of conks because if Ganoderma was the cause of death, conks will eventually be produced.
This fungus is spread by spores produced by the conk. However, once a palm is infected with G. zonatum, the fungus will move with that palm to the location in which it is transplanted. The soil around an infected palm will also contain the fungus.
More: Florida solitary bees keep flowers in bloom; here's how to attract them | Sally Scalera
In general, the fungus will be found in the lower five feet of the trunk. This has three implications. First, this means that the fungus is not spread by pruning tools since the fungus is not associated with the fronds. Second, only the lower trunk portion should not be chipped and used for mulch. Third, there are no fungicides that can systemically protect the palm either during, before, or after infection.
Once you observe a conk on a palm, the palm should be removed immediately for safety reasons. The presence of the conk means that a significant portion of the trunk is already decayed. These palms are likely to be the first blown down in heavy winds. If you can’t remove the stump, then grind it up. This will cause the infected stump material to break down more quickly. The main goal is to limit the formation of conks on any palm material left in the landscape.
If you have to remove a palm that produced a conk it is recommended that you monitor any other palms in the landscape on a monthly basis. Also, notify your neighbors so they know to monitor their palms, since the spores are blown by the wind. This could be a neighborhood effort to reduce the spread of spores of this lethal palm fungus.
More: Grow sunflowers: Birds, bees and butterflies will call your place home | Sally Scalera
Because the fungus survives in the soil, do not plant another palm in the same location where a palm has died from Ganoderma butt rot. To reduce the spread of Ganoderma butt rot within a landscape or from yard to yard, clean off and sterilize shovels and other tools that could be carrying contaminated soil. Any palm stump that is removed should be taken to the landfill and incinerated. It is best to call the landfill to arrange for the palm to be incinerated before delivery and not chipped up with the yard trash mulch.
If you have lost a palm to Ganoderma and/or you would like to improve the soil for healthier palms, contact the UF/IFAS Extension Brevard County Master Gardeners at [email protected].
Adopting different gardening practices that focus on soil health can reap some great results. After all, you need to do something different to get different results.
Sally Scalera is an urban horticulture agent and master gardener coordinator for the University of Florida’s Institute of Food and Agriculture Sciences. Email her at [email protected].
This article originally appeared on Florida Today: Fatal fungus makes palm trees conk out: Why? | Sally Scalera
