Efforts aim to save redbay population

Keeping an aging champion healthy is among the goals of an experimental effort under way at the Fort Johnson Marine Research Center on James Island.

The champion, at about 200 years old, is South Carolina's oldest redbay laurel tree. Though it's a giant among redbays, soaring 48 feet in height and with a two-foot-diameter trunk at about a human's chest level, the tree is in great danger — just like all redbays in the Southeastern U.S.

The redbay laurel, and its cousin, the sassafras tree, are being killed en masse by a fungus carried by the ambrosia beetle.

The tiny beetle and the fungus both are believed to have come to the United States on a ship from Asia through the port of Savannah in 2002. Trees in Asia have a resistance to the fungus that the trees here lack, according to Billy McCord, naturalist for the S.C. Department of Natural Resources.

The loss of redbays to a disease called laurel wilt not only deprives the Lowcountry of a popular evergreen shade tree, it also could adversely affect birds, which feed on redbay fruit, and the large and beautiful Palamedes swallowtail butterfly, which lays eggs on redbay leaves, McCord said.

McCord said he's gotten little response from local authorities, outside of Folly Beach, about the spread of laurel wilt. He said redbays don't get much attention because they lack commercial value. But he said losing redbays to the invasive beetle species and fungus is very hard for him as a naturalist with a lifetime of devotion to nature.

"Seeing the redbay die off has been particularly painful for me," McCord said.

There is hope, he said, for experiments under way at the Fort Johnson center, where dozens of redbays were treated with a fungicide (propiconazole) in April. The chemical is commonly used in Florida to protect avocado plants, which are related to redbays, McCord said.

Some trees were injected with "needles" of large and small sizes, others were sprayed on the bark. The champion redbay was injected at its base in a procedure that took hours and using a machine with tanks and tubes that looked like they were out of science fiction, McCord said.

He said other redbays received "micro injections" over a shorter time. So far, the champion redbay shows no sign of laurel wilt, and about 70 percent of the micro- injected trees appear to be resisting the disease.

However, the trees that were simply sprayed on their bark are dead or dying, McCord said.

Bartlett Tree Experts of West Ashley provided the tree injections free of charge. Bartlett arborist Mike Dunkerley, said the chemical used is carried up into the tree by natural forces that also move water. The chemical does not harm the beetle but negates the tree-killing effects of the fungus the beetle deposits as it chews tree fiber, he said.

McCord said that while the injections might prove to be a laurel wilt preventative, there's still no way to save a redbay once the fungus infests it. Even if preventive measures work, it will be necessary to re-inject every tree every year to continue the protection, he added.

Laurel wilt appears to have spread up the South Carolina coast as the rapidly reproducing beetle invaded one Sea Island after the other, while also covering some inland routes. This past winter, scores of dying and dead redbays were cut into sections and burned at Folly Beach. The effort may have slowed the proliferation of the beetle, McCord said.

Although there have not been confirmed cases of laurel wilt east of the Ashley River, it's been confirmed in Berkeley County and is raging around the Bees Ferry Landfill in West Ashley, McCord said.

McCord speculates that either redbay sections, or residue from a redbay left in a truck, were disposed of at the landfill, and the beetle invaded the nearby trees from there.

A Palamedes swallowtail butterfly count is now under way at the Fort Johnson center to establish a baseline for future swallowtail population comparisons, McCord said. He said the butterfly lays eggs on redbay leaves, which serve as a food source for the developing larvae and pupa. Unlike the ambrosia beetle, the butterfly causes no harm to the tree, McCord said.

He said a lot remains to be learned about the ambrosia beetle and the fungus, including what may happen when the two run out of redbays and sassafras to destroy.

"You can't kill your host and be a successful parasite," McCord noted.

Reach Edward C. Fennell at efennell@postandcourier.com or 937-5560.