Lethal Yellowing of Palm Trees in Florida - Palm Tree Lethal Yellowing

Department of Ornamental Horticulture Fact Sheet

Florida Cooperative Extension Service Institute of Food and Agricultural Sciences
University of Florida, Gainesville John T. Woeste, Dean for Extension

Henry Donselman*

Lethal yellowing (LY), a relatively new disease to Florida, has been recognized by other names in various Caribbean islands for close to 100 years. Jamaica's "west end bud rot," which appeared in the 1890's was a typical example. A small percentage of Jamaica's coconut palms was initially infected. The disease was not considered a serious problem until the 1950's when it began to spread rapidly in Jamaica and the Florida Keys. Because of Jamaica's economic dependence on the coconut, immediate steps had to be taken. In Florida, the Division of Plant Industry and the University of Florida cooperated in efforts to attempt to eradicate the disease.

As with any new disease, early research efforts focused on the cause. Areas investigated included fertilization and nutrition, fungi, bacteria, insects (weevils, borers, etc.) and nematodes. Initially a virus was thought to cause LY as no other disease causing agent could be discovered. Applications of fertilizers, fungicides, bactericides, and insecticides failed to control the disease. In Key West, 75% of the coconut palms were destroyed. Research from 1955-1965 demonstrated that LY was not a disease whose mysteries were going to be unraveled easily.

*Henry Donselman is Assistant Professor and Extension Specialist, Lethal Yellowing; Department of Ornamental Horticulture, Institute of Food and Agricultural Sciences, University of Florida.

The author wishes to express his appreciation to the members of the Lethal Yellowing team: H.G.Basham, Assistant Professor, Physical Biochemist, F.W.Howard, Assistant Professor, Entomologist, R.E.McCoy, Associate Professor, Plant Pathologist; and J.H.Tsai, Associate Professor, Entomologist, for their assistance in preparing this publication.