In California’s urban and natural forests, tiny beetles no bigger than a grain of rice are killing thousands of trees. Invasive shothole borers tunnel into trees, carrying with them a fungus that is food for them and their young. The damage from both the tunneling and fungal infection disrupts the flow of water and nutrients in the tree. In response, the tree seals off the attacked area and that part of the tree dies. If too many branches die, the tree dies. Sixty-five kinds of trees are susceptible to invasive shothole borers, especially common landscape trees such as sycamore, cottonwood, willow, valley oak, Engelmann oak, white alder, and box elder. There are no natural predators for this pest in California, which means beetle numbers can grow unchecked.
“As with other invasive pests with no natural enemies, shothole borer populations can grow explosively.”
Join UC Cooperative Extension Urban Forestry and Natural Resources Advisor Beatriz Nobua-Behrmann, Emeritus Environmental Horticulture Advisor John Kabashima, and Invasive Shotholes Borer Survey and Trapping Coordinator Hannah Vasilis, in a three-part video series about the biology, monitoring, and management of invasive shothole borers. Produced by Invasive Shothole Borers Communications Coordinator Randall Oliver, these videos aim to inform Californians of this harmful beetle, prevent their further spread, and provide instruction on management practices to keep trees alive.
In An Introduction to Invasive Shothole Borers, Nobua-Behrmann and Kabashima introduce invasive shothole borers. They talk about beetle biology in the tree, why we should be concerned about it, and some brief trapping and management information.
In Trapping of Invasive Shothole Borers, Nobua-Behrmann and Vasilis highlight two kinds of traps used to keep track of invasive shothole borers presence and numbers. Although visual inspections are best, traps are useful where routine visual inspections are difficult. A plant-based pheromone, quercivorol, is used to lure beetles to the traps. Learn how to handle the lures properly and the best location to place traps.
Prevention, pruning, and chemical control of invasive shothole borers are discussed in the video Management of Invasive Shothole Borers. Vasilis goes through management options and considerations. Vasilis also teaches about amplifier trees, which are heavily infested trees that can spread beetles and fungi to nearby trees. When amplifier trees are removed, lightly and moderately infested trees in the same area can survive. Chip removed trees to as small a size as possible. If the wood chips are to be moved to another area, solarizing and composting the chips can prevent any surviving beetles from spreading to new areas.
Invasive Shothole Borers website: https://ucanr.edu/sites/pshb/
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UC IPM teams up with Cooperative Extension advisors and specialists to develop instructional videos. These videos can help growers and pest control advisers monitor for pests and determine if management is needed. Find these instructional videos on the UC IPM video library webpage and UC IPM’s YouTube channel.
Also, did you know that UC IPM has more than 35 helpful home and garden videos? Go to the video library or YouTube channel to watch, learn, and do!
