Posts Tagged: palm weevil
Invasive pests kill thousands of trees, but scientists see some successes
Reposted from UC ANR news Early detection increases the chances of eradicating pests Trees...
Invasive pests kill thousands of trees, but scientists see some successes
Early detection increases the chances of eradicating pests
Trees provide shade to keep us cool, produce oxygen for us to breathe and calm our nerves. Numerous studies have demonstrated that even brief contact with trees and green spaces can provide significant human health benefits such as reductions in blood pressure and stress-related hormones. Trees also reduce noise and visual pollution, help manage storm water runoff, reduce erosion and provide habitat for birds and wildlife. Trees naturally capture carbon, helping to offset the forces of climate change. They also increase the value of our properties and communities. In short, trees are essential to our well-being.
Unfortunately, invasive pests pose an ongoing threat to California's forests in both urban and wildland settings. Invasive insects such as goldspotted oak borer and invasive shothole borers have killed hundreds of thousands of trees in Southern California and are continuing to spread. Meanwhile, other pests and diseases such as Mediterranean oak borer and sudden oak death are killing trees in Northern California.
While the situation may sound dire, it is not hopeless. Of course, the best way to stop invasive pests is to prevent them from entering the state, as the California Department of Food and Agriculture has done on many occasions. For example, several months ago, CDFA border inspectors seized a load of firewood containing spotted lanternfly eggs (a pest that is causing extensive damage on the East Coast). When pests do sneak in, the next defense is to catch them early before they become established. Finally, even if pests do become established, they can be managed if not completely eradicated.
A few examples may help to illustrate why invasive tree pests deserve action, but not panic.
Red striped palm weevil eradicated in Laguna Beach
When red striped palm weevil, a highly destructive palm pest native to Indonesia, was discovered in Laguna Beach in October 2010, a working group was quickly formed to develop a management plan. The small but diverse group included international palm weevil experts, research scientists from University of California Riverside, CDFA and U.S. Department of Agriculture, UC Cooperative Extension personnel from San Diego, Orange and Los Angeles counties and county entomologists from the agricultural commissioner's offices in Orange and San Diego counties.
The resulting response included a pheromone-based trapping program, public advisory and targeted insecticide treatments. Within two years, additional trapping and inspections could not find any signs of continued infestations. Early detection was key to the success: the infestation in Laguna Beach was identified early, so the weevil population was still relatively small. In addition, Laguna Beach is geographically isolated, the local climate is much cooler than the weevil's place of origin, and the eradication effort was well funded by state and federal agencies. Eliminating invasive pests where such conditions are not present may prove more difficult.
Invasive shothole borers attack Disneyland
The Disneyland Resort in Anaheim contains 16,000 trees and over 680 different tree species. When park officials identified an infestation by invasive shothole borers in 2016, their initial attempts at vanquishing the insects with pesticides produced mixed results. Then, they consulted with experts from UC Riverside and UC Cooperative Extension and together designed and followed an integrated pest management program that included monthly ground surveys, a trapping program that helped to detect infestation hot spots and find and remove the source of beetles, and occasional pesticide treatments on selected trees. The park went from a large number of beetles in 2017 to very low levels today. There are still some beetles, but resulting damage is extremely low, and although monitoring programs continue, the park's landscape team has been able to turn its focus elsewhere.
Goldspotted oak borer spotted in Weir Canyon
When goldspotted oak borer was confirmed in Orange County's Weir Canyon in 2014, a team from Irvine Ranch Conservancy, the organization that manages the area on behalf of Orange County Parks, sprang into action. UC Cooperative Extension and the US Forest Service assisted IRC in developing a management program, and over the ensuing years, IRC has actively collaborated with OC Parks, The Nature Conservancy, OC Fire Authority, and CAL FIRE to control the existing infestation and stop its spread. IRC has surveyed the oaks in the area yearly to monitor the infestation and guide each year's management actions.
To reduce the spread of the infestation, IRC removed more than 100 severely infested oaks in the first few years of management (no severely infested oaks have been found in the last few years of surveys). Additionally, more than 3,000 tree trunks have been sprayed annually in the late spring to kill emerging adult beetles and newly hatched offspring.
In the most recent survey of the oaks in Weir Canyon, the IRC team found only 12 trees with new exit holes, and most of those had just one to two exit holes per tree, which is an extremely low number. With the situation well under control, IRC is now considering modifying its annual spraying program and adapting other less aggressive treatment options. Finally, IRC has been actively planting acorns to mitigate losses due to the removals as well as the Canyon 2 Fire of 2016.
As these brief examples demonstrate, insect pest infestations can be managed or even eradicated if caught early enough. Early detection not only increases the chances of success, but also minimizes the cost of pest management efforts.
What you can do to prevent infestation
While management actions will vary depending on the insect or disease, species of tree and location, there are a few steps that will lead to greater success in fighting tree pests and diseases.
- Keep your trees healthy. Proper irrigation and maintenance go a long way toward keeping trees strong and resistant to pests and diseases.
- Check your trees early and often for signs and symptoms of tree pests and diseases. These may include entry/exit holes, staining, gumming, sugary build-ups, sawdust-like excretions, and branch or canopy dieback. Use available tools like the UC IPM website to determine probable causes of the problems.
- Talk with experts (arborists, pest control advisers, researchers and advisors from the University of California and other institutions), and report pest findings to your county Agricultural Commissioner.
- Evaluate the extent of tree damage and determine a management plan. Remove severely infested branches and trees that may be a source of insect pests that can attack other trees.
- Properly manage infested wood and green waste. Chip wood and other plant materials as small as possible. Solarization or composting can further increase the effectiveness of chipping. It is generally best to keep those materials close to where they originated, but if you absolutely need to move them, first make sure the facility where they will be sent is equipped to process them. Always tightly cover materials while in transit. If working with a tree care professional, insist that proper disposal is part of the job requirements.
- Many invasive tree pests can survive in down wood for long periods. When buying or collecting firewood, always obtain it as close as possible to where you are going to burn it and leave leftover firewood in place.
Palm Weevil Threat to Palm Trees
Date growers in the California deserts have many insects to worry about such as carob moth, hibiscus mealybug, and giant palm borer. Now the industry is under threat from another potential pest, the highly damaging and invasive South American palm weevil (SAPW) (Rhynchophorus palmarum). It was first identified by county and state agriculture officials in 2011 in San Ysidro in San Diego. They made the discovery while looking for a closely related palm weevil, R. vulneratus (originally mis-identified as the notorious red palm weevil, R. ferrugineus), which was found in Laguna Beach and declared eradicated in Jan. 2015.SAPW has been reported on at least 35 plant species in 12 families and is especially economically important on plantation crops such as oil and ornamental palms of which date palm, Phoenix dactylifera, is a recorded host (CABI 2016; Dean 1979; Esser and Meredith 1987). SAPW has killed hundreds of Canary Island date palms (P. canariensis) in Tijuana and parts of San Diego County. These large urban infestations pose a significant risk to the multi-million dollar date palm industries (edible fruit and ornamentals) in the Coachella Valley. Losses of ornamental Canary Island date palms in San Diego County, are probably significant and likely now reaching millions of dollars in killed palms, reduced aesthetics, and increase removal costs.
SAPW has a long rostrum (this is the beetle's snout) and is large often up to 1 ½ inches to 2 inches in length (CDFA 2018). SAPW is now California's biggest weevil species! Inside the palm crown, weevil larvae feed on the meristematic tissue and it is this feeding that kills the palm crown which results in palm death. Larvae pupate inside 3-inch cocoons made of palm fibers. The pupal stage typically lasts two to three weeks. Adult weevils emerge from these protective cocoons, mate, and they are capable of flying significant distances, perhaps as far as 15 miles in a single day, to find new palm hosts. Female weevils use their snout to chew holes in the apical regions of the palm and they lay eggs in these holes. Larvae that hatch from eggs burrow into the palm crown and feed turning the meristem tissue in a fermenting “mash”. Feeding wounds that result in fermenting damage in association with aggregation pheromone released by male weevils create a highly attractive airborne cocktail of odors that weevils fly too. Adult weevils can live for at least 40 days, often longer (CDFA, 2018).
A single infected palm can result in the production of hundreds of weevils and detection of weevil infested palms at the early stages of attack can be difficult to identify because larvae live inside their host trees. The first obvious symptom of attack is a crown that is starting to collapse. Unless palms are treated within systemic insecticides at the early stages of attack, infested palms will ultimately die in as little as 2-3 months once visual symptoms become apparent.
In addition to direct physical damage SAPW inflict via feeding, it is a primary vector of the nematode that causes red ring disease (RRD), a fatal wilt disease of palms. Fortunately, RRD has not yet been detected in SAPWs or palms attacked in San Diego (Hoddle et. al. 2016). Removal of infected trees is necessary not only to remove breeding weevil populations from the environment, but also to minimize risk of harm to people, pets, and property from crown and frond drop.
More information on the SAPW invasion and to report suspect palms please visit this website: http://cisr.ucr.edu/palmarum.html
South America palm weevil is killing palm trees in Southern California
South American palm weevils that have made their way north from Mexico are having a destructive impact on palm trees in the San Diego region, reported Abbie Alford on CBS News 8 TV in San Diego.
UC Cooperative Extension specialist Mark Hoddle, the director of the Center for Invasive Species Research at UC Riverside, toured the reporter through the hard-hit Sweetwater Reserve in Bonita, where 10 percent of the palms die every three months.
“We are going to see hundreds, thousands of Canary Island Date Palms die over the next couple of years,” he said.
The weevils use their protruding noses to drill holes in the palm, where females lay their eggs.
San Diego County Agriculture, Weights and Measurements said it plans to remove 50 infested Canary Island Palms from the Sweetwater Regional Park and is educating arborists about the invasive pest.
A spokesperson for the City of San Diego said it is working with UC Cooperative Extension.
South American Palm Weevil Conference
The South American palm weevil has successfully invaded and established in San Diego County where it has killed hundreds of Canary Islands date palms. The weevil is spreading quickly and will likely pose a significant threat to date and ornamental palm producers in the Coachella Valley.
Free Event
Date: March 12, 2018
Location: Coachella Water District, 51501 Tyler St, Coachella, CA 92236
CE and ISA Credits Available
Agenda:
8:00am: Don Hodel, UCCE LA County, will give an overview of palm biology, diseases, and nutrient deficiencies that can be confused with palm weevil damage
8:45am: Tom Perring, UC Riverside, will cover date palm pests
9:30am: Mark Hoddle, UC Riverside, will provide updates on the palm weevil invasion in San Diego County
10:15am: BREAK – Sponsored by the California Date Commission
10:45am: Mike Palat, West Coast Arborists, will review issues that need consideration when removing palm trees killed by palm weevils
11:00am: Ricardo Aguilar, Aguilar Plant Care, will discuss potential chemical control options for palm weevils in infested areas
11:15am: Agenor Mafra-Neto, ISCATech, will discuss new technologies that are commercially
available for controlling palm weevils 12:00pm: Meeting Adjourns
Register for the Meeting Here: http://ucanr.edu/survey/survey.cfm?surveynumber=22821