Palm Diseases — Fusarium Wilt

Fusarium Wilt
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.

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.

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.”

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.

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.

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.

 

The Washintonian palm (Washingtonia robusta) tends to collapse when infected with fusarium wilt.

The Washintonian palm (Washingtonia robusta) tends to collapse when infected with fusarium wilt.