- Author: Jeannette E. Warnert
Southern California's iconic palm trees are now threatened by another invasive species, the South American palm weevil, reported Mark Muckenfuss in the Riverside Press Enterprise.
Mark Hoddle, UC Cooperative Extension specialist based at UC Riverside, has been monitoring the pest south of the border and recently visited Tijuana to assess the infestation.
"We found about 130 dead Canary Island palms," Hoddle said. "It's been devastating in Tijuana."
On the way back to Riverside, he stopped in Chula Vista, where he noticed dead palm trees.
“I thought, ‘What the heck?' and yeah, it was there, too,” he said. “It was basically an accidental discovery.”
Hoddle recently reported in California Agriculture journal on the successful eradication of a different invasive beetle attacking palm trees in Laguna Beach, the red palm weevil. The cost of the eradication was more than $1 million.
In the Press Enterprise article it said the South American palm weevil is susceptible to insecticides and pheromone traps. If the beetle's presence in a palm is determined quickly, the tree can be saved.
Hoddle said he is concerned about the scope of the South American palm weevil infestation in Southern California.
"My personal feeling is we might be on the verge of a crisis now," Hoddle said in a press release issued by UC Riverside. "The big problem is we don't know how far the weevil has spread. We really need help from the public in tracking its spread."
Hoddle and other experts spoke at a symposium about the weevil at Sweetwater Regional County Park in Bonita, California.
For more about this topic, read this article from the August issue of the UC IPM Green Bulletin.
[From the August 2016 issue of the UC IPM Green Bulletin]
The South American palm weevil (SAPW), Rhynchophorus palmarum, was recently discovered in a Canary Island date palm in San Ysidro, southern San Diego County.
Twenty additional Canary Island date palms in the San Ysidro area appear to be infested, but have not yet been confirmed.
Weevil Biology
The biology of SAPW is similar to the red palm weevil that was eradicated from Laguna Beach, Orange County, between 2010–2012.
The SAPW, native to Mexico and Central and South America, destroys the apical growth of the palm by feeding on the growing tissue in the palm crown, eventually killing the palm (Figure 3). This differs from the symptoms of fusarium wilt which causes dying of lower branches.
Symptoms and Signs
Signs of the pest include accumulated frass (insect excrement) at the base of the leaves and pupal cases on the ground near the tree. Holes and tunneling can also be found at the base of palm fronds.
In addition to Canary Island date palms, the South American palm weevil is also known to attack coconut palms, date palms, and the king sago palm in the cycad family.
It is believed that the spread of this pest can be delayed with the fast detection and removal of infested trees. Chipping (Figure 4), burning, and burying infested material deeply can reduce the likelihood that SAPW will emerge and escape from infested palms.
Report a Find
-Jennifer Pelham, UCCE Area Environmental
Horticulture Advisor UCCE San Diego & Orange counties,
jlpelham@ucanr.edu;
-Tracy Ellis, Agricultural Entomologist, County of San Diego, Tracy.Ellis@sdcounty.ca.gov
/h2>/h2>/h2>/span>