Could weevils put the ‘secret swing’ tree of La Jolla’s Coast Walk Trail in jeopardy?
Trail stewards are concerned that a palm weevil infestation on a nearby tree could spread and increase the risk of using the swing.
The “secret swing” that draws thrill-seeking visitors to La Jolla’s Coast Walk Trail may be in peril. Not from overuse but because of the tiny South American palm weevil.
The swing, which was installed by trail-goers and is not sanctioned by the city of San Diego, is a makeshift rope and a tire or plank hanging from a tree overlooking the bluffs next to Coast Walk Trail. Trees that surround it in the small grove appear to have been infested by palm weevils — part of a larger infestation that has been going on in the San Diego area for more than a year. The infestation could cause the trees to die and collapse.
Several of the Canary Island date palm trees that typically stand tall, full and lush along the La Jolla coastline may be falling prey to the South American palm weevil, causing them to droop, turn brown and die.
“The weevil problem is all over the place, and there are at least two trees down there that are infested,” said Friends of Coast Walk Trail President Brenda Fake. “It’s only a matter of time until the tree with the swing gets it and falls.”
She said she has observed the signature drooping brown fronds on surrounding trees and the trees turning yellow in the center.
The South American palm weevil is a type of beetle native to parts of Mexico, the Caribbean and Central and South America. San Diego has been working since last year with the UC Riverside Cooperative Extension to develop comprehensive management of the region’s date palms, which are affected by the insect.
Fake said she has seen visitors to the trail use the swing and that she always recommends against it.
“I tell people that it is dangerous, but people are down there all the time,” she said. “I tell them using the swing is at their own risk.”
For the past several years, Friends of Coast Walk Trail has worked with the La Jolla Parks & Beaches board and the city of San Diego to carry out improvement projects on the trail, which runs between Coast Walk (a short street west of Torrey Pines Road between Prospect Place and Amalfi Street) and Goldfish Point.
Fake said she planned to meet with city representatives to see what can be done about the safety concerns associated with the swing should the area have a palm weevil infestation. There already is a sign directing visitors not to stray beyond the trail boundaries.
“I could put up a sign, but I think it would get ripped out,” she said.
Anytime the rope connected to the swing is cut, another is put in its place, she added.
However, city spokesman Anthony Santacroce said “the tree(s) in question are not on the trail but downslope from the trail. Consequently, this tree does not pose any safety issues to pedestrians and others that use and — most importantly — stay on the Coast Walk Trail. The Transportation Department doesn’t maintain trees on this rocky slope, and removing this tree would be incredibly challenging and potentially very dangerous.”
Mark Hoddle, biological control specialist and principal investigator at the UC Riverside Department of Entomology, previously said the palm trees seen across La Jolla are “highly preferred” for the weevil and that it will colonize palms and release a pheromone that attracts other weevils.
“Once at the palm, females lay eggs. Those eggs hatch into weevil grubs or larvae that feed on the palm heart,” Hoddle said. “Once the larval stage is completed, the larvae form cocoons out of palm fibers within which they pupate. After pupation is complete, the adult weevils emerge and the cycle repeats itself.”
The infestation causes drooping fronds and a collapsed or tilting crown that turns brown.
“At this stage and beyond, palms now look like giant brown umbrellas or mushrooms,” Hoddle said. Eventually the trees will die.
“Often they can’t recover because the damage is so severe,” he said. “Even if insecticides are applied, if damage is heavy, it may be irreversible. The palm can’t recover even if weevil larvae are killed off.”
Santacroce said the city encourages residents to use the Get It Done app to report signs of declining palm trees in parks or along the city right of way. ◆
1:56 p.m. March 11, 2022: This article was updated with a new comment from San Diego city spokesman Anthony Santacroce.
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