Pruning May Have Caused Palm Disease, Expert Says

Overzealous pruning with chain saws 15 years ago may have spread a mysterious disease that is causing Beverly Hills’ palm trees to lose their heads, according to an arborist working with the city.

The strange disease has weakened the trunks of the city’s Canary Island date palms and, in the worst cases, sent the one-ton crowns tumbling to the ground in strong winds.

At least 11 date palms have lost their heads in the last few years since the malady was discovered, and city staff suspect dozens more are suffering from the disease that eats away the core of the tree and triggers “sudden crown drop.”

Donald Hodel, an environmental horticulturist working as a consultant for the city, said he believes the trees were infected when pruning practices were more aggressive.

“Most of the [infected] areas on the trunk occur at the same distance from the top, so it looks like there was a specific time when this happened,” said Hodel, a nursery and landscape advisor for the UC Cooperative Extension. “When they started using chain saws to shave the leaves and shape the balls, I think they got overzealous and they created these tremendous wounds.”

Hodel and other arborists investigating the disease suspect the culprit is a fungus common in many of the topless trees--Thielaviopsis paradoxa--that is known to cause dead spots in palm trunks. Specialists in palm disease said the fungus is not contagious and can only be spread with metal implements through open wounds, but Hodel warned that the disease could be lingering in trees that were previously infected.

Meanwhile, the city’s parks department has been flooded with phone calls from residents who want to donate plant materials or send articles they think might shed light on the mystery.