- Author: Anne E Schellman
Why Not Move Firewood?
By bringing wood from home, you can unknowingly spread invasive pests and diseases that can harm trees. This includes dry, aged, and seasoned wood. Once you arrive at your destination, pests can emerge from the firewood and spread to the trees and forests where you camp. Invasive and hard-to-control pests kill several million native trees every year, causing environmental and economic problems.
Did you Know?
New infestations of tree-killing insects and diseases are often found in campgrounds and parks as a result of campers moving firewood!
This trip, tell your friends and family why you aren't bringing firewood. For more information about firewood pests and resources for finding good firewood, visit the Don't Move Firewood web site. To learn about many of the invasive wood-boring pests and associated diseases and problems, visit the UC IPM web site.
First posted on August 30, 2021
Anne Schellman has been the Coordinator for the Stanislaus County Master Gardeners since 2018.
/h4>/h4>- Author: Jeannette Warnert
Reposted from the UCANR News
California oak woodlands are highly prized ecoregions where stately trees, many of them hundreds of years old, are cornerstones of a habitat for wildlife and native plants. Sadly, some of these ecosystems are seriously threatened by exotic pests and diseases, encroachment by less desirable vegetation, and wildfire.
Each year, UC Cooperative Extension hosts workshops to share scientific developments aimed at conserving these important habitats – and the economic value of ranching – on oak woodlands, which are found on the lower elevation slopes of the Sierra Nevada, the Coast Range and other foothill areas of California.
Typically, the workshops are held in person and draw moderate-sized audiences for presentations, questions and answers, and field trips. Because of the COVID-19 pandemic, this year's workshop was offered online in April with pre-recorded presentations available for viewing at the participants' convenience and a live question-and-answer session on Zoom.
The retooled event garnered 500 registrants, over 300 views of the YouTube videos and 140 participants in the live Q&A session. The presentations and Q&A session are still available online for future viewing as well at http://cemendocino.ucanr.edu/Forestry/Workshops/California_Oak_Health.
“People from all walks of life participated, including those with professional and personal interest in oak woodlands,” said Yana Valachovic, UCCE forest advisor in Humboldt and Del Norte counties and a conference organizer.
Presentations at the 2020 conference included the following topics:
Encroachment by Douglas-fir
In Northern California, the biodiversity of oak woodlands is being threatened by Douglas-fir encroachment. The oaks' shade helps the young conifers get established with protection from harsh sun. In time, the fast-growing Douglas-fir trees pierce the oak canopies and begin to crowd out the areas' native understories, which are important for the diversity of birds, mammals and reptiles attracted to oaks.
As the Douglas-fir continue to grow and multiply, they threaten the very lives of the oak trees and the unique ecosystem they dominate.
To better understand the Douglas-fir encroachment, Valachovic established 10 research sites in Humboldt and Mendocino counties to gather information about the fate and the age of oaks. She and her research partners determined the ages of the oaks and firs, and counted the seedlings, saplings, snags and understory vegetation.
“With this research, we were able to demonstrate that even though the oak trees can be smaller in diameter, they are much older than the Douglas-fir trees,” Valachovic said. “The encroachment process is happening quickly, and the oaks are falling out of the system.”
The shift appears to have been initiated in the mid-19th and early-20th centuries, coinciding with the Gold Rush and wildfire suppression.
With the data confirming Douglas-fir encroachment, Valachovic turned her attention to oak woodland restoration. At 14 sites in Humboldt and Trinity counties, her team studied the effects of Douglas-fir removal.
“Grasses and forbs under the oaks reestablished. Diameter growth on the oaks increased,” she said.
These research findings contributed directly to changes in policy that had previously limited landowners' ability to remove and sell conifers encroaching on oak woodland. The research also helped create new funding opportunities to support oak woodland restoration and conservation in Northern California.
Case study of oak woodland wildfire recovery
In July 2018, about two-thirds of the 5,289-acre UC Hopland Research and Extension Center was burned by the River Fire.
The transformation of the land, which had likely been without a large wildland fire for at least 100 years, was intense and stressful, said UC Cooperative Extension forest advisor Michael Jones. However, it also provided a unique opportunity for researchers to compare the impact of wildfire on the resiliency of vegetation on grazed and ungrazed oak woodland.
Jones established 35 one-fifth acre research plots at the research center and collected data two months following the fire and one year later. The research will continue in the future to better understand long-term impacts, but Jones was able to share revealing early results at the workshop.
Right after the fire, in severely burned areas areas, the future of the oaks looked ominous. Jones predicted 40% tree mortality.
“The oaks were exposed to persistent, intense heat. They were cooked,” he said. “But two months after the fire, we were already seeing basal sprouts. This was an amazing response by the trees. Oaks are pretty damn tough.”
A year after the fire, surveys showed that tree mortality in the burned areas was 25%, much less than Jones' early predictions. While some management for specific situations in severely burned areas may be necessary – such as removal of hazard trees, reducing fuels in defensible spaces or removal to control invasive species – the results of this work show the trees recover naturally.
“Esthetically, I know these systems aren't as pleasing as they were before, but ecologically, they are healthy and recovering,” he said. “In 100 years, it will look just as good as before the fire.”
Fire impacts in woodland areas previously grazed and not grazed
The fire on the research station also permitted Jones to compare the fire's differing impact on non-grazed and grazed oak woodland. At first, the grazed areas looked almost unscathed with minimal flame scorching on the bark, while an area where the pasture hadn't been grazed for 25 years had evidence of much higher severity fire.
“Grazing is a phenomenal way to help manage fuels,” Jones said. However, the grazed areas displayed ecological shortcomings a year later.
“In grazed pastures, the large mature trees were still alive, but there was no oak regeneration (basal sprouting or seedlings),” Jones said. “In the ungrazed area, a lot of biomass had been killed, but there's nearly 100% resprout of oak trees and we have an impressive amount of oak seedling recruitment.”
Jones said he isn't discouraging grazing.
“But it is important to protect sites from grazing, and especially wildlife browse, when a landowner or land managers' objectives are to regenerate or conserve oak woodlands,” Jones said.
New ambrosia beetle another threat to California oaks
Akif Eskalen, UC Cooperative Extension specialist in the Department of Plant Pathology at UC Davis, has identified a new insect-fungus team that causes oak borer wilt in Northern California Valley and Blue Oaks. It is an ambrosia beetle, commonly known as Mediterranean Oak Borer, which carries several fungi in its mouth. The beetle bores into the tree and introduces fungi to grow for food. The fungi spreads and disturbs the transportation of water and nutrients, causing wilt in the tree.
The oozing and staining lesions on the bark are similar to other oak fungal diseases, such as sudden oak death. The beetle – native of Mediterranean basin countries in Africa, Asia and Europe – cannot fly far, so most likely is transported for long distances on infested firewood.
During the workshop, Eskalen suggested not moving firewood, removing heavily infested trees and chipping infested wood into 1-inch particles to reduce the spread of the ambrosia beetle and its fungal partner. He asked viewers to report any suspected oak tree infestations to the local agricultural commissioner, CDFA Diagnostic Laboratories, UC Cooperative Extension advisors or CALFIRE. Chemical options for sparing oaks from the ambrosia beetles' devastation are under investigation.
Threats to oaks and other native plants from root rotting Phytophthora
Restoration plantings have inadvertently introduced plant pathogens to native oak woodland ecosystems in California, said Ted Swiecki of Phytosphere Research, an organization that provides consulting services related to natural resource management, horticulture, urban forestry and agriculture. The group of pathogens causing the damage are largely from the Phytophthora genus, first described in the 1860s. The name translates from Greek to “plant destroyer.”
Swiecki has observed when Phytophthora infested plants and soils are introduced to native habitats, the pathogens can attack various native plants, including toyon, madrone, manzanita and full-grown oaks. Once established, the pathogen can spread along drainages, by moving soil from one area to another and by hitchhiking on equipment, tires and hiking boots.
The pathogen can easily be overlooked at nurseries, which, by their nature, have conditions that favor Phytophthora development. Plants at nurseries are well watered, have high root density and are often placed on the ground where they can pick up pathogens.
He said the best approach to tackling Phytophthora is not using nursery stock for restoration or beautification of natural oak woodland. Direct seeding, using natural regeneration, or onsite propagation are safer ways to enhance vegetation in oak woodland.
“It's easier to prevent Phytophthora from being introduced in the first place and much cheaper and more effective than trying to eradicate it later,” Siewcki said.
[Originally published in the Fall 2018 issue of the Green Bulletin. Modified slightly from original.]
Invasive insects and diseases are threatening numerous tree species throughout the country. Impacts include tree mortality, destruction of forest and urban habitats, and other significant changes in forest ecosystems due to the decline or elimination of tree species. Many of these pests can be transported in inadequately-processed wood, including firewood and discarded wood debris left behind from tree care operations (Figure 1). Preventing the spread of these pests to new areas is critical for protecting valuable forest resources. Invasive forest pests of concern include those established in other parts of the country (e.g. emerald ash borer and Asian longhorned beetle), as well as those with limited distributions in California and other areas of the western U.S. (e.g. invasive shot hole borer, goldspotted oak borer, various bark beetle species, and the pathogens responsible for pitch canker and sudden oak death).
Properly managing cut wood can effectively reduce the risk of spreading these threats to new areas. Arborists and tree care workers can help by using best management practices (BMPs) for cut wood.
BMPs need to be broad for a number of reasons:
- Some species, such as shot hole borers (Figure 2), can infest over a hundred tree species.
- They are intended to prevent the spread of a number of invasive pests.
- These pests are located in many different areas and their distributions are not definitively known.
- Incipient or outlier infestations may not be reported, making it less certain which areas may be free of invasive pests.
- It can be difficult to determine if a particular tree or wood cut from it is infested (or contaminated) with an invasive pest, including trees that appear healthy.
- Wood can become infested after it is cut from a tree.
- Even insects and pathogens that are native to a particular region of the U.S. can become serious pests when moved to an area where they don't exist. Goldspotted oak borer and pitch canker are good examples.
Basic Recommendation - Avoid moving unprocessed wood
The safest approach is to assume that all untreated wood can harbor invasive pests and therefore should not be moved from the local area. Utilize or dispose of untreated wood near the site where it was cut. Firewood outreach campaigns like “Don't Move Firewood” and “Buy It Where You Burn It” encourage this approach.
Untreated cut wood should not be left on the curbside for free pick-up (Figure 3) as there is no way to control where the wood is moved to. If wood is to be left with the landowner, talk to them about the danger of spreading invasive pests in infested wood. Handouts explaining the risk can be found at the California Firewood Task Force's website firewood.ca.gov/outreach.html and includes a Firewood Question and Answer Factsheet and Firewood Postcard. These can be printed and distributed to landowners.
Treatments to Discourage or Destroy Invasive Pests in Wood
- Grinding wood to a 1-inch minus chip size greatly reduces but does NOT eliminate all shot hole borers (SGB). Therefore, composting chips originating from near or within known SHB infestation areas is recommended. Wood should be chipped before being transported to a biomass or composting facility more than 50 miles away. If that is not possible, the receiving facility should promptly chip the material upon arrival.
- Heat treatment of infested firewood to a core temperature of 160° F for a minimum of 75 minutes has been shown to eliminate most insects and diseases.
- Complete removal of bark from branch and trunk rounds can eliminate certain insects that feed solely in or under the bark, such as bark beetles and some wood borers. Debarking does not eliminate insects that burrow in the wood or pathogens infecting the wood.
- Seasoning (drying) firewood on site for at least 2 years can reduce the risk of transporting most invasive insects. Similarly, wood that is cut from trees that have been dead for greater than 2 years is unlikely to contain living invasive insect pests, though invasive pathogens may still be present.
- Never treat firewood with an insecticide or pesticide. Doing so could result in exposure to toxic fumes when the wood is burned.
Invasive pests associated with firewood in the western U.S.
The following insects and tree diseases are found in limited areas of the western United States and represent forest health threats to hardwood and conifer species throughout the nation. Compliance with federal and state regulations is required to move wood from quarantine areas. Adhering to BMPs will limit the spread of all invasive pests and help protect our urban and native forests.
Federally quarantined species:
Sudden oak death, Phytophthora ramorum
Non-quarantined invasive species:
Invasive shot hole borers, Euwallacea spp.
Goldspotted oak borer, Agrilus auroguttatus
Redhaired pine bark beetle, Hylurgus ligniperda
Mediterranean pine engraver, Orthotomicus erosus
Balsam wooly adelgid, Adelges piceae
Pitch canker disease, Fusarium circinatum
Thousand cankers disease, Geosmithia morbida
General recommendations for handling and using firewood
- Don't move firewood long distances from where it was purchased. Use wood from local sources: “Buy it where you burn it.”
- Ask about the firewood you are buying. Is it from a local source (less than 50 miles preferred) or has it been treated to eliminate or reduce pests (e.g. heat treated or seasoned for 2 or more years)?
- When purchasing firewood for camping, buy an amount that can be completely burned during your stay. If firewood is left over, leave it for the next camper; don't take if home with you.
- Plan on cutting firewood within 50 miles of where it will be used.
- Seasoning of green wood (letting it dry) for at least 2 years or using wood from trees that have been dead for at least two years can reduce the danger of transporting most invasive insects threatening trees.
- Note that cutting standing trees can be dangerous, especially dead trees which often are unstable. Only cut standing trees if you have the proper equipment and training to do it safely.
Online Resources
Don't Move Firewood dontmovefirewood.org/
APHIS aphis.usda.gov/newsroom/hot_issues/firewood/index.shtml
USDA Forest Service na.fs.fed.us/firewood/
CA Firewood Task Force firewood.ca.gov/
Yosemite National Park nps.gov/yose/naturescience/forest-pests.htm
Buy It Where You Burn It firewood.ca.gov/pressreleases.html
- Reprinted with permission, courtesy of the California Firewood Task Force
/span>[From the Summer issue of the UC IPM Retail Nursery & Garden Center News]
When you use firewood in the great outdoors, be aware that moving firewood can transport tree-killing insects and diseases. Find out more at the following resources:
- “Don't Move Firewood,” a campaign created by the Nature Conservancy, is an informational site aimed at the general public. You can also print posters, brochures, and other handouts.
- The California Firewood Task Force website offers California-specific information about invasive species and firewood.
- UC IPM Invasive and Exotic Pests webpages contain links to relevant information on current invasive pests in California.
- The California Oak Mortality Task Force website focuses on sudden oak death, a disease affecting many woody plants
- Author: Tunyalee A. Martin
During California Invasive Species Action Week (June 2 – June 10), we highlighted several pests, but there are many more invasive species out there. Now that you know about them, share your knowledge of invasive species with others. And no matter what your summer plans, here are some things YOU can do about invasive species from the California Department of Fish and Wildlife and California Department of Food and Agriculture.
YOU: I'M TRAVELING TO AMAZING PLACES
- Learn what plants and animals you can bring into California.
- Don't pack a pest! Declare all food and agricultural items from other states or countries.
- Find out which species are threats to California.
- Learn about California's invasive plants.
- Avoid spreading forest pests: buy your firewood where you burn it.
YOU: I'LL BE WORKING IN MY GARDEN
- Remove invasive plants from your property.
- Select native or non-invasive plants for your garden.
- Use only certified weed-free forage, hay, seed, mulch, soil, and gravel.
- Learn alternatives to releasing unwanted fish, aquatic plants, and other pets.
- Monitor plants and trees for symptoms of infestations and disease.
- Learn about California's invasive plants.
- Have you spotted an invasive species? Tell us where by reporting your sighting.
YOU: I'LL BE NEAR THE WATER OR ON A BOAT
- Join the statewide citizen science effort to monitor for quagga mussels.
- Join the iNaturalist project, California Nerodia Watch, and help us find Nerodia watersnakes.
- Make sure to Clean, Drain, and Dry (PDF) your boat after each outing.
- Learn alternatives to releasing unwanted fish, aquatic plants, and other pets.
- Visit your favorite local, state, or national park, ecological reserve, recreational area, or nature center and ask about their volunteer programs.
- Learn about California's invasive plants.
- Have you spotted an invasive species? Tell us where by reporting your sighting.
YOU: I'LL BE OUT AND ABOUT CAMPING, HIKING, OR RIDING HORSES
- Use only certified weed-free forage, hay, seed, mulch, soil, and gravel.
- Avoid spreading forest pests: buy your firewood where you burn it.
- Prevent the spread of plant pathogens that damage and kill California's native plants and trees.
- Learn about California's invasive plants.
- Visit your favorite local, state, or national park, ecological reserve, recreational area, or nature center and ask about their volunteer programs.
- Have you spotted an invasive species? Tell us where by reporting your sighting.
YOU: I'LL DEFINITELY CONTINUE TO LEARN ABOUT INVASIVES
- Get to know your local invaders.
- Learn about California's invasive plants.
- Find out which species are threats to California.
- Learn alternatives to releasing unwanted fish, aquatic plants, and other pets.
- Eat them. Yum. Check out these websites to find out who is edible and how to prepare them.
- Invasive-eats.com (California-specific)
- Invasivore.org (under construction but hopefully back soon)
- EatTheWeeds.com
- EatTheInvaders.org
If you missed it this year, help in the fight next year by learning and participating during California Invasive Species Action Week.
-Dr. Jia-Wei Tay, Entomology, UC Riverside, jiawei@ucr.edu
-Dr. Dong-Hwan Choe, Entomology, UC Riverside, donghwan.choe@ucr.edu