Masterful Gardening

by Beverly Stormoen, Master Gardener

Death of the Red BayMy Nassau Sun Logo

 

Every time I leave my house, I am confronted by dying trees. I have four red bays, three of which are quite large. It is hard to find any part of Nassau County unaffected by the ambrosia beetle that is killing our red bay trees.

Newly attacked trees have few initial symptoms. The insects produce strings of sawdust which protrude from the tree. However, they are difficult to find because of their fragile structure. I have seen only a few, and by the time I get my camera, they disappear. The foliage of attacked trees soon wilts with a red to purple discoloration, which eventually turns brown but remains on the branches. It may first appear on a major branch or the entire crown. This is different from the twig borer which kills small outer branches of red bays and other trees.

Removal of the bark will reveal black striation caused by vascular fungus which will eventually kill the tree. The fungus is the same genus as in Dutch elm disease and blue stain in pines.

This beetle, like other ambrosia beetles, does not feed on the wood, but on the fungi the adult female injects. It takes only one beetle burrowing into a tree's cambium layer - the vascular growth area - and depositing the fungus to kill an entire tree. Most ambrosia beetle species attack stressed, dead or dying trees, but this species attacks healthy trees.

The beetle, about 2mm in length, is native to India, Japan and Taiwan and was first detected here near Port Wentworth, Ga., in 2002. There are 12 species of non-native ambrosia beetle species thought to have been introduced in wood packing materials, such as crates or pallets, since 1990. In Florida, this particular ambrosia beetle was first reported in 2005 in the Timucuan Preserve.

Today, all red bays with a diameter greater than 6 inches have died on Fort George Island. The range of infestation is Charleston County, S.C., to St. Johns County, with Union, Putnam and Alachua counties newly added.

There are field trials of pesticides being conducted, but at this time, there is no treatment for prevention or control of the beetle or the fungus.

To avoid spreading the beetle or fungus to unaffected areas, it is suggested that infested trees be cut, chipped on-site and left as mulch. Firewood should not be transported. Every precaution should be made to keep infested trees out of counties with no reported infestation.

The disease, called laurel wilt, has affected other individual plants in the laurel family, such as pond spice, pond berry, avocado and sassafras.

Replacement trees should not be in the laurel family. Hardwoods like oak, cherry, maple, ash, elm or nut trees may be safe choices.

 

 

 

 

Beverly Stormoen

Beverly Stormoen lives on Amelia Island and is an active Master Gardener volunteer.