B. Rosie Lerner
Extension Consumer Horticulturist
Treated Lumber and Alternatives in the Garden
Gardening in raised beds can be just the answer for would-be gardeners,
who would love to grow their own vegetables and flowers, but lack the
space or physical ability for a traditional garden. However, recent controversy
regarding chemical wood preservation treatments has left many gardeners
wondering about the safety of treated lumber.
Many gardeners have made use of treated lumber in their raised beds, fences,
benches, gazebos and other landscape structures. Up until about 2003,
many of us used a then commonly available treated lumber product called
chromated copper arsenate (CCA). But in 2002, the Environmental Protection
Agency (EPA) announced that CCA treated lumber would be phased out for
use in consumer/residential products over the following couple of years
due to concerns regarding the safety of arsenic. Since then, several more
environmentally friendly alternatives to CCA treatments have become available,
although existing stockpiles of CCA treated lumber can still be used.
Alkaline copper quaternary (ACQ) is a water-based fungicide/insecticide
combination that is higher in copper than CCA but is free of arsenic.
This type of treated lumber can be used for above-ground structures, as
well as those underwater. ACQ treated wood can be painted or stained and
is available at many lumber suppliers.
Copper Azole is another combination fungicide/insecticide treatment, but
this type of treated lumber can only be used in above-ground structures
(no underwater usage). It, too, can be painted or stained.
There are alternatives to treated lumber, including synthetic composites
made from recycled plastic or rubber, vinyl fencing and naturally rot-resistant
woods, such as cedar and redwood. Other materials, such as stone, concrete
block and brick, provide alternatives to wood.
For more information regarding the CCA alternatives, visit the EPA Web
site at http://www.epa.gov/oppad001/reregistration/cca/alternativestocca.htm.
Editor's note: The Feb. 17, 2005, Yard & Garden column, "Leaf
Spots Not Always From Pests," was missing two words at the end of
the first sentence in the last paragraph. The correct version of the paragraph
Spotting of African violet leaves can also be avoided by using room-temperature
water. Then water can always be supplied from above, preventing the salt
buildup. You will still have to ensure that the drainage water does not
become reabsorbed. A simple way to prevent re-absorption is to set the
pots up on rocks, bricks or other support so that the bottom of the pot
is out of the reach of the drained water.
We apologize for the error and any inconvenience it may have caused.