I would too without a second thought. We tend to forget that even way back when the CCA issue was at its peak and was not recommended for gardens, the recommended spacing between the boards and the produce when it was used was only 6". 17 year old boards are no problem IMO. Dave

Ditto on the Osage Orange Keith. Around here it is called Hedge and is highly valued for fence posts, very commonly used by ranchers putting up barbed wire fencing. I've seen posts having been in the ground in excess of 50 years that are still solid. There may be another alternative, a show yesterday showed sodium silicate treated deck planking being used on a newly installed house deck. Apparently, the silicate (glass) gets infused into the wood sealing it up from moisture.

Sharon, I am always going to be more cautious and conservative on this issue than most people because I prefer to err on the side of safety. While it is true that CCA lumber has been replaced by ACQ lumber, there is no way we can know if the copper in ACQ leaches at a high enough rate to be considered a health risk. Already, they have brought out a newer version of ACQ called MCQ (the copper in it is microprocessed)because of issues that involve leaching and staining and corrosion of metal fasteners used with ACQ. It took 40 years for the health risks of using CCA to be fully studied and understood, and then it took another 10 years for it to be banned and phased out. (Being overly cautious, our family stopped using it long before it was finally banned.) So, I think it is really too soon for any possible risks of using the newer treated lumbers to be fully studied and understood. Maybe 10 or 20 years (or more) down the road, we'll find out that ACQ or MCQ are not really any safer than CCA was. On the other hand, maybe we'll find out there are no significant risks. Who knows? For me, the choice is not to use it. I don't even like using copper fungicides very often because copper can build up in your soil, and too much copper is a bad thing. I don't want to use this lumber now and find out 5 or 10 or 20 years down the road that studies show a link between using it and health issues. One method I use to judge a product like this is to check with ATTRA to see if the product is allowed in Certified Organic food production. If it isn't allowed, I won't use it. So, I checked, and ACQ is not allowed in Certified Organic operations. Everyone has to decide what their own comfort level is when it comes to using pressure-treated wood (or anything else) in their edible gardens and make their decision based on what they find acceptable. I'd just rather use plain untreated wood and have one less thing to worry about. I've linked the ATTRA publication on treated lumber. It discusses ACQ further down on the page. Dawn Here is a link that might be useful: Pressure Treated Wood

What kind of grooves are you speaking? If these are cracks opening up in the wood there is nothing that you can do to stop it and filling the cracks will make things worse.