Copper Azole in Wood: Safe for the Vegetable Garden?

[Anneke]

I'm building a raised bed for my veg garden this year. My landscaping timbers are treated with copper azole, which I understand to be safer than the usual compound used in pressure treated wood because it does not contain arsenic.

Does anyone have information on the toxicity of this chemical? Does it leach into the soil?


TIA

[KYHeirloomer]

The copper compounds in treated wood are being used to replace arsenic, as you note.

According to the testing done, they do not leech.

However, there's some question as to leeching of the original treated wood, when used in gardening. There's evidence to indicate it was all a tempest in a teapot.

But the new pressure treated wood should be perfectly safe.

[Anneke]

Thank you KYH. Back to drilling I go....

I was researching the topic last night and found an article that suggested that if the copper leached into the soil, it would kill the plant before it could produce anything edible. So overall, I feel pretty good about it.

[KYHeirloomer]

I've seen those sorts of comments, Anneke. They rank right up there with the idea that if you grow in old tires zinc will leech out and kill your plants.

Copper is sometimes used as a fungicide. So, if it were dangerous to the actual plants in the minute quantities we're talking about, it would not be a treatment for anything in your garden.

All of that belongs to the "if it sounds right it must be right" school of science, as opposed to the controlled experiment school. And you'd be surprised how many people subscribe to it.

FWIW, all the original to-do about pressure treated centered on the findings that there was a higher incidence of arsenic in the drip lines of raised decks than in the surrounding soil. Almost everything else was extrapolated from that (even the issues involving playground equipment), rather than from actual studies.

Sometimes the government is too **** protective!

[Anneke]

Populist environmentalist demagoguery is big business. I am appalled at the lack of critical thinking behind opinions on such an important topic. People like being told what to do but don't like to be perceived as such. Hence the school of "If it sounds good..." as you mention. Unfortunately with the lack of science background, it's not always easy to weed through the garbage that is posted on the web, so I'm really glad you chimed in.