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I am planning a 9′ x 14′ arbor/pergola type structure attached to my house on one 9′ side. First I was told that I shouldn’t use 4″x4″ treated posts because 1) they would start to twist in a year or so, and 2) that it’s not good to use treated lumber when planning to grow grapes on it. That I should use either 4″x4″ or 4″x6″ cedar or redwood for the posts. Now I have been told that the arsenic in the treated lumber wouldn’t hurt the grapes and that if I use cedar or redwood instead of treated lumber, it will be drilled full of holes by carpenter bees within a fairly short time – that I should use treated 6’x6’s for the posts. I live in Arkansas where there are LOTS of bugs, so I tend to believe the person that told me about the carpenter bees. Anybody out there with an opinion on this? I would appreciate it.
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....carpenter bees are good carpenters... and they like nice homes.. their favorite is a horizontal board that they drill their nice 5/8" hole up from the bottom and then turn either left or right and make their horizontal chamber about 10" - 12" long...they sleep in there and hibernate in there.. nose to butt...sometimes we rip old stock in the winter and find a dozen or more just sleeping away...
they can make swiss cheese out of anything... they can be controlled but not eliminated...
they like horizontal members better than vertical posts, and they like cedar , redwood , & pine better than Treated...
like all good carpenters they are not very aggressive, but will defend their homes...
The treated is not going to hurt your grapes or you...
b I like carpenter bees...Kermit
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Personally, would not use treated lumber ANYWHERE you plan to grow things that will be FOOD. The arsenic etc WILL leach out into the surrounding soil(see plenty of Organic Gardening Magazine articles on this subject). Would painting the posts discourage the carpenter bees? What about using either Osage Orange or Black Locust for the posts instead(I've heard that these woods are VERY rot resistant, but I'm not certain about insect resistance)?
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I built a 10 X 14 pergola 8 years ago. Used all treated wood and 6X6 posts ( it is free standing ). The carpenter bees leave it alone but attack my redwood deck constantly. If you paint wood they won't bother it. Have lived in the country all my life and have sent many carpenter bees to an early grave with a badmitton racket. Am told that only the female bees have stingers, so don't swat at the ones wearing skirts. Good luck
*Margrit,Organic Gardening has long been sounding the klaxon over PT wood with no scientific or medical evidence to back them up. They are stridently alarmist, yet they are hardly an authority on this issue.
*There are alternative methods of treating lumber that do not utilize the heavy metals of arsenic and chromium. I believe that there are several companies that provide such treatments in addition to the standard CCA or AZCA treatments. Unfortunately, lumber yards in my area will only special order it at extra cost. One such product from an Oregon company is listed at: http://www.conradwp.com/acq.htm Do a search on ACQ or "treated lumber" and I assume that you will find other suppliers, although I haven't done such a search in about a year.On Arsenic, this excerpt from an article in todays San Francisco Chronicle (2/25/00) on arsenic in drinking water might be of interest:Arsenic, a known carcinogen, is widespread indrinking water, particularly in the West. It isgenerally associated with water from heavilymineralized aquifers rather than from surfacesources, such as reservoirs. Last year, a report by the National Academy ofSciences identified arsenic as a pernicious toxicant,one that can cause bladder, skin, kidney and lungcancer if consumed over a long period of time. Ithas also been linked to diabetes and cardiovasculardisease. At issue is the federal safety threshold for arsenic,which has stood at 50 parts per billion (ppb) since it was adopted in 1942. According to the National Academy of Sciencesreport, someone who, over their lifetime, consumesdrinking water with an average arsenicconcentration of 50 ppb has a 1-in-100 risk ofdying from cancer. That risk is several orders of magnitude higher thanthe EPA usually allows for tap water. The highestrisk the agency typically allows is a 1-in- 10,000risk, which in the case of arsenic would correlate toa concentration of 0.5 ppb. Under a congressional directive, the EPA wassupposed to adopt new guidelines for arsenic indrinking water by Jan. 1, 2000, but the agencymissed its deadline. There have been several lengthy discussions regarding treated lumber on this board some months ago. You might want to do a search and check them out also.I would guess the concern would be as to how much arsenic from the lumber leaches into the soil and how much from the soil is taken up by the plant material that you eat. (And, I guess, how risk averse that you are...) The arsenic in new treated lumber is fairly tightly encapsulated so the initial problem is primarly in the contamination on the surface of the lumber from the treatment. Once the treated lumber starts to break down (which it will eventually do) or burns then the arsenic will be released into the environment. As I understand it, intact treated lumber is exempt from being considered as toxic waste but sawdust and treated lumber that is rotted, burned, or damaged in such a way as to allow the release of the heavy metals must be considered toxic waste and must be disposed of accordingly.
*I have to disagree with the statements of trated lumber being safe around plants grown for food. THERE IS DOCUMENTATION showing the link. And yes, I use a lot of treated lumber in my jobs. I will try to find the references && post them.
*....love to see your documentation...but I have to say , those tomatoes tasted great last year, and the zucchini too!!...and I didn't eat the termites , even though they ate my treated garden stakes.....LOLKermit
*Theresa, here in Tidewater VA, the carpenter bees regularly bore into treated pine, so don't count on the treated wood as being "bee-proof". Redwood is a magnet for these busy beavers, probably because it's so soft.Boringly, Steve
*do they bore into the verticals or just the horizontals.....how many you count in one chamber?are they using the new Makita boring machines???haven't seen 'em in Trex yet... and didn't see 'em keel over after spitting out the Treated...LOL
*...gotta say... Carpenter bees are the artisans in the insect boring world.....so that must make the Carpenter ants the "hackers"and the termites the vandals..and the powder post beetles the graffitti artists..while the Formaosan termites sound like "Alien " come to earth....if you don't like P.T. try some of the borates, like Tim-bor...or Bora-care.. or some of the injection devices/products..
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I am planning a 9' x 14' arbor/pergola type structure attached to my house on one 9' side. First I was told that I shouldn't use 4"x4" treated posts because 1) they would start to twist in a year or so, and 2) that it's not good to use treated lumber when planning to grow grapes on it. That I should use either 4"x4" or 4"x6" cedar or redwood for the posts. Now I have been told that the arsenic in the treated lumber wouldn't hurt the grapes and that if I use cedar or redwood instead of treated lumber, it will be drilled full of holes by carpenter bees within a fairly short time - that I should use treated 6'x6's for the posts. I live in Arkansas where there are LOTS of bugs, so I tend to believe the person that told me about the carpenter bees. Anybody out there with an opinion on this? I would appreciate it.