Dying Trees

Mysterious Disease Kills Australian Trees
Discovery Earth Alert, August 2, 2000

Forests near the harbor of Sydney, Australia, have been stricken by an unknown illness that has killed up to 70 percent of the city's lofty angophora trees, Sydney's "quintessential" tree. The tree, Angophora costata, distinguished by its smooth salmon-colored bark, is suffering from a widespread and unknown form of dieback. The disease has denuded the city's forests and left only skeletal remains of the trees, which often grow to 100 feet. Brenda Madden, North Sydney Council's bushcare officer, reported that whatever the illness is, it is attacking the root systems, preventing nutrients and water from being absorbed. The council is so concerned about the rate the disease is spreading that they are beginning a program of injections to bolster the immunity of the angophoras. Many residents with waterfront homes have tried to have the trees removed in order to improve their views. Nutrient runoff from the hillside gardens may also be stressing the trees and making them more susceptible to the disease. Dr. Brett Summerell, Royal Botanic Gardens plant pathologist, reported that a preliminary analysis of soil samples taken from the bases of diseased trees had failed to provide an explanation. "We want to do a proper survey for any pathogens," Dr. Summerell said. "There's certainly something that seems to be affecting just the angophoras. It's really quite bizarre the way they're all dying both young trees and mature trees. There's no other species that seems to be affected."