Ils n’ont pas lambiné les scientifiques américains et particulièrement ceux de l’University of California, Riverside, Mark Hoddle, plusieurs fois cité déjà dans notre site, ils viennent de tenir une première réunion sur ce nouveau ravageur de palmiers. En dehors de cette réactivité exemplaire, on relève que la stratégie de lutte s’appuie autant sur le piégeage que l’utilisation des insecticides. Deux concepts qui n’ont pas vraiment la côte chez nous ce qui explique beaucoup de choses !
Les scientifiques insistent beaucoup sur la détection préventive en affirmant qu’il n’y a pas encore de technologie réellement efficace. (SNP va peut-être les surprendre bientôt.....). La quarantaine est également évoquée comme possible réponse. Rappelons qu’en France en dehors du passeport phytosanitaire, il n’y a guère de contraintes au commerce des palmiers, ce qui jure un peu avec le méga-dispositif que vient de mettre en place la commission européenne. http://www.sauvonsnospalmiers.fr/spip.php?article1586
Enfin le groupe de travail s’est inquiété du risque supplémentaire que constituerait the red ring nematode bien que non présent encore en Californie.
Scientists work to define threat from palm pest
by Kevin Hecteman - Ag Alert
Category : California News
Published : 03 November 2016
“That makes it difficult when you’re trying to reach the urban constituents and why it’s a concern to them,” he said. “Palms are extremely important to our urban, coastal California landscaping. It’s very much an urban issue right now, and we don’t want it to become an ag issue.”
Nick Condos, who directs the Division of Plant Health and Pest Prevention Services at the California Department of Food and Agriculture, talked about potential regulatory responses to the threat ; besides trapping and pesticides, these could include quarantines, control methods, outreach and research.
“We have put in a farm-bill request to do a trapping program for exotic palm pests, which would include South American palm weevil,” Condos said.
Details still need to be worked out, he said, as it’s not yet known how far north or east the weevil has spread.
As for a quarantine, Condos said it’s not yet known exactly which varieties of palm are susceptible to weevil infestation. Any quarantine would likely take after a plan drawn in 2012 to combat the red palm weevil in Laguna Beach, though that plan was never activated. Quarantines can be expensive to enforce, Condos said, and can involve steps such as growing nursery stock in an enclosed structure for a year and safely transporting frond trimmings.
“Nobody was rooting for a quarantine right now,” he said. “It was just an opportunity to get all these options out there, let people start thinking about them and what we need to do, to prioritize research to pursue some of these options.”
Hoddle said drooping fronds and a tilted crown are signs a palm tree has weevils. Trouble is, by the time one sees these signs, the tree may be beyond help.
“One of the holy grails for palm weevil research is early detection,” Hoddle said. “How do you know if your palm tree’s infected before you start seeing these very obvious visual symptoms ? Right now, there’s no really great early detection technology.”
As if all that isn’t enough, the weevil has a partner in crime : the red ring nematode. If this pest is in the tree, it will find its way into the weevils, which then spread it to other trees. But so far, Hoddle said, the nematode has not appeared in California.
The best chance of containing and eradicating the weevil is when the population is small and localized, he said. The most effective anti-weevil tactics involve using pheromone traps and pesticides simultaneously ; traps won’t stop the infestation but will help locate affected trees.
“Then you want to apply the pesticide treatments to those infested palms,” Hoddle said. “That type of multi-pronged approach has been really effective at controlling date-infesting palm weevils in the Middle East, for example.”
Condos said CDFA will encourage palm growers to participate in weevil detection.
“Most of our successful pest responses over the past couple of years have a very large commodity presence,” he said, citing efforts to combat pests threatening citrus crops and winegrapes.
“We really wanted to make sure that (farmers) understood that this isn’t government alone,” Condos said. “They have to be part of the process.”