Ms. Koblinsky grew up in The Ranch, and, after a career in Washington, D.C., and Maryland, retired and moved back here several years ago. She continues to undertake volunteer work on public health and local issues.
Invasive, long-nosed South American Palm Weevils have now killed more than 20,000 ornamental and Date Palm trees in San Diego County, including hundreds of majestic Canary Island Date Palms in Rancho Santa Fe. Residents are lamenting the loss of one of our community’s iconic landscape features. RSF’s Forest Health Study (FHS) found the Canary Island Date Palm to be the fourth most common of 150-plus Covenant tree species, with an estimated 16,500 trees on our residential properties, golf course, and public areas.
Talk by Leading Weevil Expert
Responding to this threat, the Association and Forest Health and Preservation Committee have invited Dr. Mark Hoddle to present important updates on prevention and treatment of the South American Palm Weevil infestation. His talk will take place on Wednesday, Jan. 25, from 5:30 – 7:00 pm, at the RSF Golf Course Clubhouse. Dr. Hoddle is Director of the Center for Invasive Species Research at University of California Riverside, where he investigates pests threatening Southern California ecosystems. He has studied the South American Palm Weevil for seven years and is a leading researcher of this pest.
Dr. Hoddle’s talk and Q&A session will cover South American Palm Weevil biology, its spread and damage, trapping and insecticide treatments, palm removal, and management of infected palm material. He will also describe a new approach, “Attract and Kill,” to lure and kill the invasive pest. A recent million dollar grant from the California Department of Pesticide Regulations will test an environmentally friendly, less expensive method for reducing the weevil populations than the current insecticide applications to palm foliage and soil. His grant also provides an opportunity for select communities to participate in the research.
Hoddle states that: “Without a doubt, this is the worst palm pest California has ever dealt with. Once these weevils get into a palm tree, they lay eggs in the palm, and those eggs hatch into these really large larvae which destroy the palm heart. The first sign of infestation is seeing the crown droop and turn brown. The tree can’t grow any new fronds and all you are left with is a halo of dying fronds . . . It’s basically a death sentence for a palm tree.”
RSF Palms in Peril
Rancho Santa Fe’s identity has long been heavily intertwined with its trees. In 2018, the RSF FHS estimated that a good grouping of skyline trees increases the value of RSF homes by 10-20% — equating to $300,000 to $600,00 per home and boosting property values of all Covenant homes. Canary Island Date Palms are found throughout the community and are the most expensive palms to replace when lost. The mature palms often cost upwards of $20,000 with installation fees of $5,000.
Many RSF homeowners admit to being caught off guard by the rapidly spreading infestation. While the palm weevils prefer to feast on Canary Island date palms, they’ve also been found to lay eggs and kill a variety of Southern California palms, including Fan, Triangle, Senegal, Sabal, Guadalupe, Chilean Wine, Bismarck, and Pritchardiapalms. Some residents are relying on protective applications of insecticides to save high-valued trees, which are applied several times a year and cost several hundred dollars per treatment.
New Treatment Approach
Hoddle’s new grant project, “Fatal Attraction,” will test a new pheromone treatment specific to the South American Palm Weevil. The pheromone will be mixed into a waxy matrix with a very small amount of insecticide that only kills if the insect touches it. A dollop the size of a quarter can be applied to small hanging traps or objects such as a fence or lamp post.
“The weevil flies to it, walks over it several times, realizes there’s nothing to mate with and flies off. By the time it’s gone, it’s gotten a lethal dose of insecticide,” Hoddle said. Researchers predict that as they increase the number of dollops in the infested test areas, weevil numbers will decline and palm trees will survive in higher numbers.
Hoddle is hopeful about the prospects of saving more heritage palms but realistic about outcomes. This will be the first time this new technology has been applied on such a large scale and success is not guaranteed. However, Hoddle and the state have had prior success in defeatingother invasive pests. The Red Striped Palm Weevil from Indonesia was detected attacking palms in Laguna Beach in 2010. Hoddle’s team responded rapidly with pheromone traps, insecticides, and destruction of infested palms to attract, trap, and kill this deadly pest. With the cooperation of state and federal agencies, UC researchers, and Laguna Beach homeowners, Red Striped Palm Weevils were last detected in 2012 and declared eradicated in January 2015.*
* For more information about weevils or help in evaluating the health of your palm trees, please contact RSFA Environmental Resource Coordinator Caitlin Kreutz at caitlin@rsfassociation.org or (858) 756-4652.
