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Fusarium Wilt Disease of Queen and Washingtonia Palms

Two Mexican fan palms were killed after tree trimmers spread fusarium by pruning a neighbor's queen palm (arrow) with infected saws.
Diagnostic asymmetrical necrosis and petiole streaking visible on an infected queen palm frond.
Queen palms can also suffer from cold damage which presents very similarly to fusarium wilt. Rachis streaking and cross-sectional petiole analysis can help distinguish the two issues.

Fusarium wilt is a relatively new disease of queen palms (Syagrus romanzoffiana) that has moved into the North Florida and is commonly spread by infected pruning equipment. 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.

The fungal spores are mostly spread by wind, improperly cleaned pruning equipment, and evidence has shown infected palms can spread the disease to other nearby palms through the soil.

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 to take special precautions about who prunes your queen palms and Washingtonian palms, how they prune and how they disinfect their pruning saws.

Chainsaws and Polesaws cannot be adequately disinfected, which contributes to the aggressive spread of the disease in the urban landscape. Many high-end resorts, with significant investments in ornamental palms, mandate that trimmers use only hand saws to trim palms because those tools can be disinfected.

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.

For more information, see this article by the University of Florida on Fusarium Wilt.