Invasive Shot Hole Borers
Invasive Shot Hole Borers
Invasive Shot Hole Borers
University of California
Invasive Shot Hole Borers

Wood Disposal

Wood from PSHB-infested trunks and branches is still full of live beetles. If infested wood is not properly handled, beetles will emerge from the cut logs and attack new hosts. This two-phase process will help prevent the beetles from spreading to other locations (or re-infesting your own property). Details on each procedure can be found below.

 

Phase One

Wood chips from a PSHB-infested sycamore (John Kabashima / UC Cooperative Extension)

Wood chips from a PSHB-infested sycamore (John Kabashima / UC Cooperative Extension)

Chip infested wood immediately after tree removal or pruning. Running PSHB-infested material through a wood chipper is one of the most effective ways to kill the vast majority of beetles living in cut logs.

  • To destroy as many beetles as possible, chip wood to a diameter of 1 inch or less
  • Do not leave piles of contaminated wood uncovered - if wood cannot be chipped immediately, tightly wrap the logs in plastic to contain the beetles
  • Cover unchipped wood in transport
  • If wood cannot be chipped, tightly cover cut logs and follow directions for solarization or kiln-drying

 

Phase Two

After chipping infested wood, select one of the options below to ensure that beetles and fungi are destroyed. Some of these methods also work for logs that cannot be chipped. 

 

Solarization

This method is suitable for handling both infested chips and logs. When done correctly, solar energy will heat plant material until both the beetle and fungi are killed.

How long does infested wood need to be solarized? Solarization is most effective during the peak of summer, when temperatures are higher and days are longer, but it may be used during other seasons as long as time and space can be committed.

  • July - August: cover chips/logs with sturdy plastic for at least 6 weeks
    • Temperatures during these months should be regularly above 95°F
  • September - June: cover chips/logs with sturdy plastic for at least 6 months

Other tips for proper solarization:

  • Use sturdy plastic sheeting/tarp that can withstand rain/wind
    • TIP: Clear plastic lets more sunlight through and heats the content more efficiently
  • Fully contain chips and logs (and beetles) by wrapping plastic both underneath and over the material
  • Keep log/chip layers as thin as possible (2 logs deep maximum) to ensure even heating throughout the pile

 

Composting

Proper composting can effectively control the plant pathogens that cause Fusarium Dieback. Composted, chipped plant material may then be re-purposed as mulch or added back into soil to improve texture and water retention.

It is recommended that wood chips be composted at a professional composting facility that has earned the US Composting Council's Seal of Testing Assurance (STA). Facilities in the STA program are tested for proper decomposition and pathogen control.

Find a local STA Compost Facility at the US Composting Council website.

Composting can also be done at home, as long as guidelines for adequate decomposition are carefully followed. These general composting guidelines will help assure the destruction of Fusarium euwallaceae:

  • Woody material should be chipped to less than 1 inch in diameter.
  • A mixture of equal volumes of green plant and dry plant material will normally achieve a proper carbon-to-nitrogen ratio of 30 to 1.
  • Do not add soil, ashes from a stove or fireplace, dairy or meat products, or manure from meat-eating animals.
  • A pile should be in bins at least 36 x 36 x 36 inches to assure adequate heating.
  • Maintain a temperature of 160°F, turn the pile every 1-2 days, and add nothing to it once the composting process has begun. If temperatures do not reach 160°F within 1-2 days, the pile is too wet or dry. If too dry, add water. If not enough nitrogen, add green material.
  • Healthy compost has a pleasant odor, gives off heat as vapor when turned, has a white fungal growth on the decomposing material, gets smaller each day, and changes color to dark brown. Compost is ready when no further heat is produced.

These guidelines are based on the requirements listed by UC IPM. Find additional composting tips from the UCCE Master Gardeners or from CalRecycle.

 

Kiln-Drying

Unchipped, PSHB-infested wood can be decontaminated by the heat used in kiln-drying. To destroy the fungi that cause Fusarium Dieback, it is necessary to heat the material for at least 60 minutes at 60°C. Wood that has been disinfected can then be re-purposed.

When transporting infested wood to another facility for treatment, always cover the material in transit.

 

Biogeneration

Biogeneration facilities burn green waste and convert it into energy. When transporting infested wood to another facility for treatment, always cover the material in transit.

 

Landfill

Wood chips can be transported to some landfills, where they are used as Alternative Daily Coverage. When transporting infested wood to the landfill, be sure to cover the material in transit.

 

This site contains research-based information for education purposes. For specific guidance check with your local land management regulatory authorities. Any information on products and practices is for educational purposes only and does not constitute an endorsement or recommendation by the University of California.

Webmaster Email: sldrill@ucanr.edu