Sally Scalera

Brevard County Horticulture Extension Agent
3695 Lake Drive -- Cocoa FL 32926 -- 321-633-1702

Bad news for Bay trees

Nov. 10

For everyone who has redbay trees (Persea borbonia) in their yard, I have some sad news to pass on.

A beetle native to India, Japan, Myanmar and Taiwan came into the United States and brought with it a fungus that kills redbay trees. It has been killing redbay trees in Georgia, and it has found its way into Brevard County.

They also refer to this disease as the laurel bay wilt or laurel wilt disease. To give you a little history, the redbay ambrosia beetle was first discovered near Port Wentworth, Ga., in 2002. In one year, this beetle caused a large amount of redbays to die within a 40-mile radius of where it was discovered.

By 2005, the redbay ambrosia beetle had moved into the coastal areas of South Carolina and Georgia. Also in 2005, large numbers of redbays had died in the Timucuan Ecological and Historic Preserve in Duval County, and in October 2005, it was confirmed that the redbay ambrosia beetle was the cause.

The ambrosia beetle introduces a vascular fungus, causing the infected redbays to wilt and die within a few weeks to months.

The redbay ambrosia beetle is a small, elongate, cylindrical beetle that is about 2mm long. This beetle looks very similar to the dozen other beetles, some of which are native, that are in the same genus and that we have in Florida.

To truly identify the redbay ambrosia beetle, the beetle needs to be examined by an entomologist.

To identify an infected redbay, look for:

• Small strings of compacted sawdust, which form a tube and may stick out from the bark at the point of attack. These strings can disintegrate quickly and are not always present.
• Removal of the bark around the bore hole will reveal shot holes. A dark stain will extend from these holes into the surrounding xylem.
• Attacked trees eventually exhibit wilted foliage with a reddish or purplish discoloration. This discoloration may first appear in a portion of the canopy or, the worst extreme, where the entire canopy wilts together, becoming discolored.
• The wilted foliage eventually turns brown and will stay attached to the branches.

In addition to killing redbays, this beetle and fungus also kill sassafras trees. There are many other members of the laurel family, such as swamp bays, silk bays, pondspice, avocados and pondberry, also called southern spicebush. It is not known yet if these other members of the laurel family are susceptible to the disease.

After the redbay wilt was found in Duval County, it later showed up in Indian River County (about 140 miles south). The first thought that comes to mind for this large jump in area is redbay firewood was moved from an infected area down to Indian River County. So a word of warning: Do not move firewood with you when you camp. Instead, buy it locally when you get to your destination.

In one monitoring plot in Duval County there was a 92 percent mortality rate of redbay trees, where all redbays taller than 6 inches in diameter died. The ecological impact of the laurel wilt disease could be severe because the trees are important to many types of wildlife. The seeds of the redbay are eaten by quail, turkey, deer, songbirds and bears. The leaves of the redbay are also the food source for palamedes, Schaus and spicebush swallowtail butterflies. The palamedes only use the redbay tree as their larval food source. The loss of redbay trees would not only impact the species that use the redbay as food but it could also change fire behavior.

The worst news is there is no way to control or stop the spread of these insects and their fungus. The only plan for the future is to collect redbay seeds and save them. I know it doesn't sound very optimistic, but there doesn't appear to be any way to stop the destruction.

If you have dying or dead redbays in your yard, cut the tree down and chip it on site to keep from spreading the beetles to another area. And remember, don't transport redbay firewood.

For further information on the laurel bay wilt, including pictures of the beetles, the sawdust tubes and dying redbays, go to http://pestalert.ifas.ufl.edu.

In addition to this information, there also is information on the Redbay Seed Collection Program. This is the time of year when the redbay seeds are produced, so if you have some seeds and some time to collect them, check out where to send the seeds so that we can have redbay trees in the future.