Palm in peril - Sabal palm trees

American Forests, Jan-Feb, 1994 by William Carrino

Something is killing the stately Sabal palm, Florida's state tree. Could it be literally drowning?

FOR UNTOLD CENTURIES, the Sabal palm tree has thrived along what is now Florida's Gulf and Atlantic coasts. Native Americans are believed to have relied on the hardy palm for both food and shelter almost 10,000 years before the first European explorers arrived.

Since no artist's rendering of the southland's tropical shores would be complete without tall Sabal palms bending in the breeze, they have become universally synonymous with the Florida landscape. The Sabal's history is so embedded in Florida's history, in fact, that in 1953 it was designated the official state tree. At that time the Sabal, also known as the cabbage palm, was thriving in wild coastal and inland groves.

By the early 1970s, the tree had reached peak numbers in the state, and, since the Sabal had no known natural enemies, its future looked bright. Often living for more than a century and achieving heights of up to 80 feet, the Sabal is drought-resistant, cold-tolerant, and withstands the unrelenting Florida sun, and its fronds, or leaves, do not wither in the coastal salt air.

Considering the tree's many positive attributes, it was perplexing when observers noticed that Sabal palms were beginning to die. At first the decline was slight and barely noticeable. It was explained away as the natural evolutionary process of environmental pruning, survival of the fittest trees within the overpopulated groves.

As the decline became increasingly more obvious, the blame was placed squarely on harvesters who were removing the Sabal's buds and embryonic leaves--the heart of the tree--to make highly prized Sabal-palm honey. The Florida Department of Natural Resources (DNR) quickly stepped in, and the latter half of the 1980s saw the practice of Sabal-honey harvesting drastically curbed. But to the astonishment of the DNR and the state departments of agriculture and forestry alike, the 80-foot giants continued to drop their fronds and wither in the broiling sun.

Although it is clear that the tree has been struggling for survival for at least the past 10 years, the last two have seen a dramatic and devastating increase in the number of palm deaths.

As sightings of dead and dying Sabals became more frequent, the Florida Department of Forest Management, headed by Chief William Helm and George Albritton, set up a computer bank to track the problem areas. Reports of throngs of dead Sabals began pouring in from a wide range of Florida locations. Initially, it was thought the blight had stretched as far south as the Tampa Bay area and as far north as St. Mark's National Wildlife Refuge on the Florida Panhandle. As George Agrios and Francis E. Putz of the University of South Florida's botany department compiled all the data, they found that mature Sabals were inexplicably dropping their fronds and dying by the thousands along a 200-mile stretch of Gulf Coast.

But the blight was not confined to the Gulf Coast, as originally thought. Researchers at USF and the state's department of agriculture have now confirmed major regions of sick Sabals on the Atlantic Coast near Jacksonville, Ormond Beach, and even as far north as the Cumberland Island National Seashore in southern Georgia.

What each of the reporting communities had originally considered to be a perplexing problem unique to its own area was now becoming an environmental disaster of statewide proportions. "This is the largest congregation of dead and dying trees that I have seen in all my 14 years in forestry," said Ed Barnard of the Department of Forestry in Gainesville. "We have run a gamut of tests and have eliminated a number of possible causes."

Barnard and a team of other forest pathologists attacked the problem head-on by running a battery of tests on the blighted trees. The most obvious villain was believed to be the dreaded palm weevil, but Barnard quickly ruled that out. After weeks of intensive testing, some other likely suspects--like bud rot--were ruled out, as were various forms of fungi and root disease.

One by one, every known and likely sickness was considered, investigated, and ultimately eliminated. With their options decreasing daily, Barnard's team tested for, and then ruled out, a rare disease known as lethal yellowing, even though Sabal palms have long been thought to be resistant to it. This vicious disease wiped out broad ranges of coconut palms in South Florida nearly 20 years ago.

Then, in early 1993, a seemingly routine report of yet another blighted area was entered into the data bank. It described a 430-acre site in the west-central town of Yankeeville, about 70 miles north of the Tampa Bay area. The property owner, David Ohlwiler, reported that among the thousand or so Sabal palms on his land--some of them at least 100 years old--there were large pockets of decimated trees. Some of the stands were practically blackened by the intense sun, while others just a few hundred yards away seemed to be in perfect health. "I don't know what is killing the palms," Ohlwiler said in his report to the Florida Department of Forestry. "I wish I did. These old trees are so beautiful, and it's a shame to sit by helplessly and watch them die."