Posts Tagged: street trees
UC Davis Researchers Link Vehicle Pollution to Elevated Insect Damage to Street Trees
Trees planted near streets and highways are subject to elevated insect damage due to the adverse...
Vehicle pollution is associated with elevated insect damage to street trees, UC Davis researchers said in their paper published in the Journal of Applied Ecology. They studied insect damage to native oak trees.
UC Davis lab experiments showed that caterpillars preferred the native oak leaves from the nearby streets and highways.
Cities in California inland areas must make street tree changes to adapt to future climate
Many common street trees now growing in the interior of California are unlikely to persist in the warmer climate expected in 2099, according to research published in the July 2018 issue of the journal Urban Forestry & Urban Greening.
“Urban foresters in inland cities of California should begin reconsidering their palettes of common street trees to prepare for warmer conditions expected in 2099 due to climate change,” said the study's co-author, Igor Lacan, UC Cooperative Extension environmental horticulture advisor in the Bay Area.
Common trees in Coastal California cities appear to be better suited to withstand the 2099 climate.
“Our research shows that some trees now lining the streets of cities like Fresno, Stockton and Ukiah are likely to perform poorly in 2099,” Lacan said. “Those cities need to look at the conditions – and trees – now found in El Centro, Barstow and Fresno respectively.”
To reach these conclusions, Lacan and co-author, professor Joe McBride of UC Berkeley, used space-for-time substitution. They compared the most common street tree species in cities representing each of the 16 California climate zones with trees in cities that currently have climates that approximate the expected warmer conditions in the 16 cities 80 years from now.
For example, Eureka can expect a climate like Berkeley's today; Fresno's climate will resemble the climate of El Centro today. (Find the complete list of cities below.) The corresponding cities were determined with climate predictions from Cal-Adapt, which synthesizes California climate change scenarios to reach a consensus view of the magnitude of climatic warming.
“We used the mid-range models,” Lacan said. “It's very reasonable to say the warming predicted by the model we used is already ‘baked in,' regardless of any mitigation efforts. While we should take measures to prevent even greater warming – mostly by reducing the use of fossil fuels – this study aims to help adapt California urban forests to the warming that can be reasonably expected to occur.”
Lacan said he and McBride were surprised to find that coastal cities and their warm equivalents contain most of the same common urban tree species, while the warm equivalents of inland cities seemed to lack most and, in some cases, all of the common trees there today.
“It's really a sharp distinction,” Lacan said. “Perhaps they were lucky, but coastal cities are better positioned for the climate of 2099 than the inland cities.”
Climate zone |
City |
Corresponding city |
1 |
Eureka |
Berkeley |
2 |
Ukiah |
Fresno |
3 |
Berkeley |
Santa Ana |
4 |
King City |
Stockton |
5 |
Santa Maria |
Santa Ana |
6 |
Santa Monica |
King City |
7 |
San Diego |
Santa Ana |
8 |
Santa Ana |
Burbank |
9 |
Burbank |
Fresno |
10 |
Riverside |
Barstow |
11 |
Yuba City |
El Centro |
12 |
Stockton |
Barstow |
13 |
Fresno |
El Centro |
14 |
Barstow |
El Centro |
15 |
El Centro |
Furnace Creek |
16 |
Susanville |
Barstow |
For a copy of the complete research report email Igor Lacan, ilacan@ucanr.edu.
New Tools for Managing Polyphagous Shot Hole Borer
As discussed in previous issues of this newsletter, polyphagous shot hole borer (PSHB; Euwallacea sp.) is a new pest/fungal complex attacking a wide variety of host trees in Southern California, from avocado to common residential and street trees and native oaks and riparian species. The PSHB is morphologically identical to the tea shot hole borer, E. fornicatus, but a genetic analysis confirmed that this is a new species of ambrosia beetle. PSHB has been found to carry several symbiotic fungi, including new fungal species Fusarium euwallacea, andan undescribed Graphium species.It was first identified in 2003 in Whittier Narrows, an undeveloped riparian area in Los Angeles County, and was officially first linked to tree injury and mortality in a residential avocado in 2012. Since then, the pest complex, also referred to as Fusarium die-back, has spread throughout Southern California and is now present in Los Angeles, Orange, San Bernardino, Western Riverside, and San Diego counties. The population in San Diego County is a different genotype from that found in the rest of the region, possibly indicating a separate introduction. The pest/disease complex has caused significant impacts to the avocado industry in Israel, and is now spreading in commercial groves from Escondido to Fallbrook. It has caused injury and mortality of hundreds of ornamental trees in the urban areas, impacting roadways, botanical gardens, parks, and private residences, and impacts all major native riparian trees species. The official list of reproductive hosts, meaning trees that can support growth and reproduction of the beetles and fungi, includes 35 species with several having been confirmed in just the past few months.
The plant pathology, IPM, environmental horticulture, and natural resource management teams working on this pest at UCR and UC Cooperative Extension in San Diego, Orange, Los Angeles, and Ventura Counties have put together several useful tools that can help you manage this pest. These include a new field identification card set, a decision tree for tree removal, a guide to managing infested plant materials, and information about how to report an infested tree and how to collect samples for lab identification, as well as a continuously updated web-based map. You can find these at www.pshb.org.
To determine if your trees are affected by this pest:
- Look for a small (tip of a ball point pen) round entry/exit hole surrounded by wet discoloration of the outer bark
- Follow the gallery to look for the beetle (may or may not be present)
- Look for other hosts (Castor bean, sycamore, maple, coast live oak, goldenrain, liquidambar) showing symptoms of the beetle/disease
- Report suspect tree infestations to eskalenlab@gmail.com with the following information:
o Your contact info (name, city, phone number, email)
o Suspect tree species
o Description of suspect tree's location (and/or GPS coordinates)
o Description of suspect tree's symptoms
o Photos of suspect tree and close-up photos of symptoms
- If symptom photos and descriptions indicate it might be PSHB/FDB a field assessment may be needed or a sample can be submitted following detailed directions on how to collect and submit a sample for fungal confirmation at pshb.org.
To protect your trees, avoid movement of infested firewood and chipped material out of infested areas. Infested material should be chipped to under 1”, wrapped in clear plastic, and solarized on site for up to 6 mos (depending upon environmental conditions). Research is ongoing in the use of insecticides and fungicides, as well as exploration of the use of endophytic bacteria as a biocontrol agent. If you suspect that you have found this beetle or seen symptoms of the Fusarium dieback on your tree please contact the Ventura CE office, your pest control advisor or qualified arborist, or contact UC Extension Plant Pathologist Dr. Akif Eskalen by at akif.eskalen@ucr.edu. For more information visit www.pshb.org or http://eskalenlab.ucr.edu/avocado.html.
PSHB DAmage
PSHB damage
Ginkgo!
Recently a friend asked me about landscape trees for her yard. She was thinking of choosing a...
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