I won't get termites in my retaining wall or garden bed, right? After all, it's treated!
There is a certain amount of truth to this statement, however, other factors need to be considered.
Ineffectiveness of treatments - Some treatments are not effective in the long term and require regular re treatment, which of course, in the "real world" is seldom done.
Effective treatments can be dangerous - Some treatments effectively protect timbers from fungal decay and termites, however, they can be potentially more dangerous than we would like. (CCA)
1) Not all timbers are durable in the weather - Some timbers are able to withstand extreme weather and attack from pests, others, however, may not be so durable.
Although some timbers are treated, this may preserve them for a period of time, these may not last extended period of time and may eventually fail to protect the timber.
Although this timber retaining wall was treated, after many years the treatment has failed to prevent fungal decay. Although no termites ate the timber, the fungal decay will eventually cause the timber to fail.
Other treatments may be highly effective, but may be dangerous. At the moment, an effective treatment for preserving timber against termite attack and fungal decay is Copper Chrome Aresnate (CCA). If you think that sounds a lot like arsenic, you'd be right! It's still used for preserving timbers found at your local hardware stores. We actually managed to find several examples in a local hardware store chain here in Australia. Similar treated timbers are easily sourced in the USA and other countries as well.
Studies suggest that the arsenic in CCA treated timber can can leach out through physical contact and via water contact.
Whatever treatment may have been used on this retaining wall post was no longer protecting it from termite damage.
These Termites Schedorhinotermes Sp. were discovered in a timber retaining wall on Lake Macquarie.
The maintenance program on this timber retaining wall was not regular enough to prevent fungal decay.