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Orange County Focus

COUNTYWIDE : Fatal Fungus Is Killing Palm Trees

August 29, 1994|HOLLY J. WAGNER

One of the quintessential symbols of California--the palm tree--is in danger because of a fatal fungus that has stricken landmark palm trees in Dana Point, Corona del Mar and other Southland cities, officials report.

"People don't realize they're living things, and they have perils that they're susceptible to," Newport Beach General Services Director David Niederhaus said. "We're going to see a significant denuding of the area over time."

Canary Islands date palms are particularly susceptible to fusarium wilt fungus, and heat accelerates the trees' deterioration, said Howard Ohr, a plant pathologist at UC Riverside who is one of the nation's leading authorities on palms and palm diseases.

"It's spread all across the state. . . . Many of the cities that have Canary palms have it," he said. "The biggest thing that's misunderstood is how serious it is. Once it's in the tree, it's going to die. You try to prolong their life by good nutrition and good water, but the longer you do, the more danger there is of spreading."

The fungus gets into the tree's circulatory system through use of unsterilized cutting implements, he said.

"When you cut a green frond, that's when you infect the tree. This particular fungus lives in the vascular system of the tree. It blocks all the water-conducting tissues of the tree," Ohr said.

The best way to avoid spreading the fungus is to trim only brown leaves and sterilize saw blades for five minutes with a 50-50 solution of chlorine bleach and water, Ohr said. Using reciprocating saws is better than using chain saws, he said, because blades can be switched and sterilized between trees.

"You won't ever eradicate it, but you can reduce its occurrence," Ohr said, adding there is no known chemical treatment and no research underway. "Research takes money and, it's a sign of the times, there's no money for it."

In Corona del Mar, palms along Marguerite Avenue from Ocean Boulevard inland to Fifth Street will begin disappearing over the next year, and because of their age it is impossible to replace them with palms of similar size, Newport Beach arborist John Conway said.

To make matters worse, trees weakened by fusarium wilt are more susceptible to another fungus, pink bud rot, which also preys on the more graceful, slender California fan palms.

Mature Canary Island palms cost about $2,500 each now, Conway said, and he predicted that increased demand will drive the price up.

"The decision has not been made about what size and age (of trees) to use for replacements," Conway said. "It's not recommended that you install the same kind of trees as replacements because the fungus can get into the soil. We're going to recommend some alternate type of palms that would not be as susceptible."

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