A perfectly green good looking palm tree with no symptoms the crown just snaps off or reen palm tree snaps in half caused by Thielaviopsis trunk rot by the fungus Thielaviopsis paradoxa. One of the several diseases that have no cure
How does the Thielaviopsis trunk disease attack the palm tree?
Thielaviopsis trunk rot is caused by the entrance of the fungus Thielaviopsis paradoxa into the palm through a wounded tissue.
The palm canopy may appear to be healthy prior to collapse, a field diagnosis can be done by inspecting the trunk for stem bleeding 1 to 5 feet at the base with foamy white fluid that smells like wine coming out of cracks or small spots about the size of a penny or larger that is moist, soft or wet finally an area of the palm that turns black.
The only way to know for sure is with lab work by taking a cross section slice of the palm and submitting it for analysis for confirmation.
Fresh trunk wounds may become infected by the fungus so limiting manmade wounds to the palm trunk, especially the upper third of the trunk is important. Infected palm should be removed immediately, and the diseased trunk portion destroyed but not recycled. Do not plant another palm in its place.
Tree pruning should only be performed on dead, fronds you should never remove green fronds from a palm tree. Sterilizing equipment after contamination with sick palm or between palms is vital to prevent the spread of diseases from palm to palm.
Excessive pruning or over pruning of palm trees such a Mohawk trim will cause severe damage and stress to palm trees by weakening the canopy and thinning the trunk making it more susceptible to diseases and breakage in high winds. There is no such a thing as trimming palms for hurricane season palms are naturally hurricane ready if left alone.
Treating trimmed trees canopy or wounded areas immediately with an active ingredient Thiophanate-Methyl in Cleary 3336 can help prevent the disease from spreading and possibly cure sick palms see supporting documentation bellow.
List of palms affected by Thielaviopsis trunk rot in South Florida
African Oil Palm
Betel Nut Palm
Canary Island Date Palm
Mexican Washington Palm
True Date Palm
Sources of info
Thielaviopsis Trunk Rot of Palm https://edis.ifas.ufl.edu/pp143
THIELAVIOPSIS DISEASES OF PALMS http://fshs.org/proceedings-o/2004-vol-117/324-325.pdf