Laurel wilt disease

Monday, April 4, 2011

Our native red bay tree (Persea borbonia) is a primary host plant for the Palmedes Swallowtail butterfly. The fruit also is eated by deer, songbirds, black bears and wild turkeys.

Red bay is related to two other native trees, swamp bay (Persea palustris) and lancewood (Ocotea coriacea). These trees are in the laurel family, along with avocado (Persea americana).

All of them are vulnerable to a disease that has spread from South Carolina down the coast and into Miami-Dade County.

The fungal disease is killing swamp bay trees along Krome Avenue, between Kendall Drive and Tamiami Trail, according to Alejandra Castro-Nunez of the Miami-Dade County Consumer Services Department.

The disease is spread by an Asian ambrosia beetle, first found in this country in 2002. It is apparently attracted to the aroma of these laurels and when it invades the trees, it introduces the fungus. Leaves wilt, but often stay on the branches. New shoots appear, but they also die, and eventually the trees are killed.

Work is under way to determine the best way to control the beetle and the disease. According to Castro-Nunex, a fungicide called Alamo can treat redbay trees only, but must be injected using special equipement.

The Florida Department of Agriculture and Consumer Services has a Website with significant amounts of information on the disease and the beetle. Go to and scroll down to  Plant Industry, under the heading Divisions. Click on it, and you'll find the link. Another online resource is

If your red bay, lancewood or avocado show symptoms, contact the Division of Plant Industry at 1-888-397-1517.