Part of me wants to say that we shouldn’t be burning firewood in our home fireplaces because it’s the fastest way to convert sequestered carbon into atmospheric CO2. Maybe I’ll save that discussion for another day. In the meantime, there’s a more immediate and local issue with firewood.
In southern California, we are experiencing significant losses of trees as a result of the introduction and spread of various invasive “tree pests”. When trees in homeowners’ yards die from these invasions and are removed, it has been common practice to save larger pieces of the tree and cut them to firewood size. It makes sense to use this wood in your fireplace (if you have one), right? Why turn down free firewood? Even better, why not sell the firewood and make a little money? However, if the tree died from an attack by an invasive pest, there is a high likelihood that the wood saved and cut for firewood is still infested with the pests that killed the tree. This can present potential problems for remaining healthy trees in the neighborhood, surrounding natural areas, and even other cities or counties (if the firewood is transported elsewhere for sale).
Improper handling of firewood can spread pests and diseases and cause unnecessary tree mortality. Here are a few suggestions to help reduce the spread of unwanted pests and diseases among our urban and natural forests.
If you are a homeowner keeping your firewood, the following solarization process will reduce the chance of spreading pests:
- Carry out these steps within a few days of the tree’s removal. Sooner is better!
- Store the firewood away from your home and away from other trees, preferably in a location where the pile will be in the sunlight for most of the day.
- Cover the stacked firewood with sturdy clear plastic sheeting (do not use tarp, many pests are sneaky and will find ways to escape this material).
- Fully contain logs by wrapping plastic both underneath and over them.
- During July – August: cover logs with sturdy plastic for at least 6 weeks.
- During Sept. – June: cover logs with sturdy plastic for at least 6 months.
- Keep log layers as thin as possible (2 logs high at maximum) to ensure even heating throughout the pile.
If you are a homeowner using woodchips as mulch onsite, the following solarization process will reduce the chance of spreading pests:
- Cover the mulch with sturdy clear plastic sheeting (again, do not use tarp, many pests are sneaky and will find ways to escape this material).
- Fully contain chips by wrapping plastic both underneath and over them.
- During July – August: cover chips with sturdy plastic for at least 6 weeks.
- During Sept. – June: cover chips with sturdy plastic for at least 6 months.
- Keep chip layers as thin as possible to ensure even heating throughout the pile.
If you are a homeowner not keeping your firewood or mulch:
- If your pruning contractor is removing the wood, be sure that they know the risks and how to address them properly (see below).
- Do not leave (or allow your contractor to leave) the wood on the curb for passersby or neighbors to pick up.
- Do not offer the wood to friends and family who don’t live in the immediate area. If they live close by, be sure they understand the proper precautions to treat the wood to kill invasive pests (see above).
If you are a pruning contractor:
- Cover all material from infested trees during transit.
- Chip all materials to less than 1” chip size.
- Deliver chipped materials to landfill for use as daily cover, or to an STA approved compost facility.
- Do not store logs without solarizing first (see above). Do not deliver logs to firewood lots without solarizing first, or assuring that the firewood lot will solarize immediately following delivery.
- Do not deliver chips to another site as mulch without first solarizing the chips or instructing the recipient as to the need to do that (see above).