Invasive Spotlight: Goldspotted Oak Borer (GSOB)
Adult goldspotted oak borer, Agrilus auroguttatus, on an oak leaf. Photo by Mike Lewis, Center for Invasive Species Research, Bugwood.org
There are several flatheaded boring beetles in California, however only a few are of particular concern. The goldspotted oak borer (GSOB), Agrilus auroguttatus, is a metallic wood-boring beetle that threatens our native trees. Since it was introduced to Southern California on contaminated firewood in the early 2000s, this pest has caused extensive damage to woodlands and native oaks.
What does the goldspotted oak borer look like?
Adult GSOB are 0.4 inch long and 0.08 inch wide with bullet-shaped bodies. They are black with an iridescent green sheen and six distinct gold spots on their back.
What damage does the goldspotted oak borer cause?
Goldspotted oak borers only attack oaks (Quercus spp.). They are particularly damaging to coast live oak and California black oak. Adult beetles lay eggs on host trees and the larvae bore into the wood, feeding on the tree's vascular tissue. The larvae feed on the tree until they pupate into adults and exit the tree, leaving D-shaped exit holes in the bark. Extensive GSOB feeding can girdle trees, disrupting water and nutrient uptake and eventually causing the tree to die.
What can you do about the goldspotted oak borer?
Don't move firewood! The most important way to prevent the spread of invasive wood borers like GSOB, is to buy firewood where you're going to burn it. If you live in an area of Southern California where GSOB is present, avoid planting susceptible trees. If you need to remove an infested tree, keep the cut wood away from healthy oaks and tarp or grind the wood to kill any larvae present. To report possible sightings, fill out the Goldspotted Oak Borer Symptoms Reporting Form at https://ucanr.edu/sites/gsobinfo/What_You_Can_Do/Report_GSOB_Symptoms/
Invasive Spotlight: Highway Iceplant
You've probably seen this invasive plant growing along highways or the coast in California. Highway iceplant, Carpobrotus edulis, was intentionally introduced to prevent soil erosion along highways and coasts but it has since invaded many different ecosystems and outcompetes native plant species. The California Invasive Plant Council (Cal-IPC) rated this plant as an A-1 species, meaning it is one of the “most invasive and damaging species that are widespread in the state.”
What does highway iceplant look like?
The highway iceplant, also known as the hottentot fig, is a succulent with fleshy three-sided stems. It grows as dense ground-covering mats and produces large yellow to light pink flowers in the late spring and early summer.
What can you do about highway iceplant?
For decades iceplant was widely promoted as an ornamental landscape plant. While its popularity has dwindled, it may still be available for sale in some nurseries. Avoid buying and planting iceplant. Instead, choose plants native to California and visit the PlantRight website to find similar-looking alternative plants. If you have iceplant on your property, it can easily be removed by hand pulling. Be sure to get all live shoots as it can regrow from any node left behind.
The Asian Citrus Psyllid (ACP) is a small, aphid-sized insect that poses a serious threat to California's citrus trees. This invasive pest can carry and transmit a fatal bacterial disease called Huanglongbing (HLB) to all citrus species. HLB has already decimated citrus groves throughout Florida, costing the citrus industry millions of dollars. The psyllid is currently present in Southern California, but preventative measures can keep the disease and insect from spreading to California's citrus growing regions.
What does the Asian citrus psyllid look like?
Asian citrus psyllid adults are 1/6 to 1/8 inch long with brown wings and red eyes. They feed on plants at a 45-degree angle, with their heads down and back end in the air, unlike any other citrus pest. Their feeding causes twisted or distorted leaves. Nymphs are wingless, flattened, orange to brownish, and are generally found on young leaves and shoots. Both adults and nymphs feed on plant sap and excrete honeydew, but nymphs produce distinct waxy tubules to help clear the sugary waste from their bodies.
What are the symptoms of Huanglongbing disease?
An early symptom of HLB is irregular yellowing of leaves, on an individual limb or in one sector of a tree's canopy. Yellowed leaves are blotchy or mottled, but not symmetrically yellow like a nutrient deficiency. As the disease progresses, the fruit will become smaller, more bitter, and may not ripen properly. Once trees are infected, it may take up to two years for obvious symptoms to occur and trees can die within 5-10 years.
What can you about the Asian citrus psyllid and Huanglongbing disease?
It is estimated that 6 out of every 10 California residences have at least one citrus tree on the property. Inspecting your own citrus trees is vital to prevent the spread of ACP and HLB. Check your citrus trees for the Asian citrus psyllid, especially in spring and fall when new growth is abundant. If you think you have found ACP or suspect HLB infection, contact the CDFA Exotic Pest Hotline at 1-800-491-1899 or your local county agricultural commissioner.
To learn more about Asian citrus psyllid and Huanglongbing disease, see the UC IPM Pest Notes: Asian Citrus Psyllid and Huanglongbing Disease and view UC IPM's online training.
California Invasive Species Action Week!
The 10th annual California Invasive Species Action Week (CISAW) will kick off Saturday June 3rd and runs to Sunday June 11th. This week is designed to raise awareness and encourage public participation in the ongoing fight against invasive species. These invaders are non-native plants, animals, or pathogens that can negatively impact our waters, native ecosystems, agriculture, health, and economy.
You can participate during Action Week and all year long by doing the following:
- Check out UC IPM's previous blog posts on invasive species.
- Burn firewood where you buy it. Do not move firewood to different counties. Visit the California Firewood Task Force website for more information.
- Find out if there's a pest quarantine in your area and what you can do to minimize spread from the California Department of Food and Agriculture.
- Don't plant invasive species and when possible, try to plant California natives. Visit the PlantRight website for more information on plant selection.
- Report invasive species to your local County Agricultural Commissioner.Contact information for your location can be found at the California Department of Agriculture County/State Liaison page.
- View the full schedule of events for Action Week at the California Invasive Species Action Week website.
Help us observe Invasive Species Action Week and the fight against invasive species!
- Author: Maria Murrietta
The UC Master Gardener volunteer program serves the citizens in San Luis Obispo County to help them flourish and maximize their success in the garden. Master Gardeners work to maintain the Garden of the Seven Sisters in San Luis Obispo, a hands-on educational facility that also provided the local community with over 1,100 lbs of fresh produce in 2019, through donations to the SLO County Food Bank Coalition.
It takes a lot of people and a variety of resources to run the Garden the Seven Sisters which provides science-based learning opportunities that focus on sustainable garden practices.
For example, in 2019, our 90 Certified Master Gardener volunteers achieved the following:
- Over 5,000 hours of work and completed 1100 hours of continuing education.
- 500 people consulted Helpline for garden information and advice
- 1,000 people attended our monthly Advice to Grow By workshops
- 350 people attended the Fall Festival
- 100 people attended the Lunchtime in the Garden, many of whom were seeing the garden for the first time
- Master Gardeners facilitated 18 additional speaking engagements, and staffed 10 information tables at community events and festivals
- Our new class of 2020 includes 32 new trainees who are currently completing 54 hours of educational training to become certified Master Gardeners.
All these efforts and accomplishments would not be possible without the generous support of the SLO County community.
Save the Date: June 5th is World Environmental Day and the Big Dig Day. This is the day to Dig Deep and support the programs you care about. We invite you to support the programs and services that enrich our county.
Every dollar counts. Your donation of just $15 to the Master Gardener Program of SLO County could help us purchase soil and seeds for the donation plot.