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Thread: Keeping wood free of powder post beetles

  1. #31
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    REsurrecting this thread - I have some Red Oak from a large tree I cut down in my yard. It has been air drying for over two years now. I'm slowly starting to use it in some projects. I have two stacks about 5' tall x 4' wide by 9 ' long. I just noticed some small holes, and dust - I am guessing I've got powder post beetles in my wood. After reading this thread, I'm thinking I need to treat the wood with a boric acid wash. Is it too late, if they have already bored into the wood? Do I need to take the stickered stack apart to spray it all, or can I just put the pump sprayer in between the layers, and spray away?

    Any tips appreciated.

  2. #32
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    Three months ago I had cut down a lot of Bradford pear for my wife's wood turning hobby and stacked it under the lean to shed. There are probably 75 pieces 20 inches in diameter and 30 inches long. Two weeks after placing it under the shed it showed signs of active powder post beetle infestation (little strings of sawdust coming out of the ends which it been sealed with anchorseal). I called my local pest-control guys and they had me "tent It" heavy plastic with bricks around all the edges. They came out and put some sort of chemical in pie plates to fumigate the wood. They had me keep it under plastic for three days and there's been no sign of critters since. I supplied the vinyl and all the labor and it cost me a whopping $30 for them to administer the chemicals. I previously tried the boric acid wash on cherry logs with very poor results.

  3. #33
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    Thans for this valuable response, Tom. I'd love to know what chemical the pest control guys used and if the infestation has abated or only delayed.

  4. #34
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    Quote Originally Posted by Kevin Guarnotta View Post
    I'm thinking I need to treat the wood with a boric acid wash. Is it too late, if they have already bored into the wood?
    I could be wrong but it's my understanding that treatment with a borate is a preventative, not a cure as it may not penetrate far enough to kill all the existing larvae. (those little holes and frass piles you see are the PPB's exiting the lumber after they mature) Heating the wood to 132 degrees at the core for a minimum of four hours is recommended for reliably killing an existing infestation. After heat treatment, then treat with a borate to prevent re-infestation.
    Cody


    Logmaster LM-1 sawmill, 30 hp Kioti tractor w/ FEL, Stihl 290 chainsaw, 300 bf cap. Solar Kiln

  5. #35
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    Quote Originally Posted by Tom Davis View Post
    There are probably 75 pieces 20 inches in diameter and 30 inches long.
    That's a lot of huge Bradford Pear...the equivalent of 23 x 8' long logs or 3000 bf Doyle scale.

    Was that 20" diameter or circumference?

    I, too, would like to know what they used to fumigate the logs.
    Cody


    Logmaster LM-1 sawmill, 30 hp Kioti tractor w/ FEL, Stihl 290 chainsaw, 300 bf cap. Solar Kiln

  6. #36
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    Quote Originally Posted by Cody Colston View Post
    I could be wrong but it's my understanding that treatment with a borate is a preventative, not a cure as it may not penetrate far enough to kill all the existing larvae. (those little holes and frass piles you see are the PPB's exiting the lumber after they mature) Heating the wood to 132 degrees at the core for a minimum of four hours is recommended for reliably killing an existing infestation. After heat treatment, then treat with a borate to prevent re-infestation.
    Cody, the borate is both a preventative and it will also kill the larvae when they hatch and bore out of the wood. Heating is indeed the best way.

    The problem with borate treating dry lumber is that the liquid causes the wood cells to expand, and then they will contract after drying - potentially causing surface checking. In some instances (such as a log cabin), you don't have many other options but in the case of furniture wood it is a solution, but not necessarily the best solution.

    Yonak, you can build a home sterilization chamber and heat treat the boards yourself for not a lot of cost or hassle. There was an article in FWW a few years back that detailed the process. If you send me a PM with your e-mail address I'll be happy to send you the method.

  7. #37
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    Scott,

    I realize the topical treatment will kill the PPB's as they bore out of the wood but what about the eggs that they leave behind? Also, I believe that PPBs can incubate for years before hatching. How long do borate treatments last?

    I treat my lumber with Timbor immediately after sawing, as I sticker and stack it. The lumber is already wet. Can additional wetting of the surface cause surface checking? I've not really noticed it if it can/does.
    Cody


    Logmaster LM-1 sawmill, 30 hp Kioti tractor w/ FEL, Stihl 290 chainsaw, 300 bf cap. Solar Kiln

  8. #38
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    Great Idea, thanks!

  9. #39
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    The stuff the pest guys used was PH3 , Aluminum Phosphide fumigant tablets.

    Cody - the bradford pear count is 45 20"-22" with the rest 15"+. The loading, unloading, and stacking all most finished me off.

  10. #40
    Quote Originally Posted by Cliff Rohrabacher View Post
    Painful experience has taught me to Pre-Treat all my home-seasoned lumber with an aqueous solution of Boric Acid. I make my own by boiling boric acid powder in water till no more will go into solution. Then I spray it on using a one gallon poly pump sprayer. I get the boric acid from an Agway.

    The bugs that are already inside will eventually bore out. The ones outside that find the wood will eventually try to bore in. In either event the bugs have to tackle that outer 1/8” or so of surface wood where the solution penetrated. Then they die.

    Just boric acid in water is not the optimum solution. What you want, for PREVENTION ONLY, is what they sell as "Timbor." It's water, boric acid and borax. Again, on freshly-milled lumber, or inside lumber being put outside for the first time, Timbor will prevent infestation, but that's all. It also can leave a white residue, which can cause problems later with finishing.

    However, if you have lumber that already may have been exposed, then you need to spray it all with "Bora Care." This cost a lot more than Timbor, but it penetrates all the way through the wood, and kills any eggs & larvae already in there Timbor does NOT do this. Let's be very clear:
    TIMBOR DOES NOT KILL EXISTING INFESTATIONS.

    Realize that once you see the little mounds of dust, the bugs have already left the lumber, and have likely done tons of damage inside. If you see no dust mounds, they could be in there right now, chomping away, and they could emerge 2 years later, after you've built and finished you furniture.


    I recently posted a detailed thread on how to make both solutions at home, for less than half the price of the retail stuff.
    Last edited by Allan Speers; 07-10-2015 at 9:55 PM.

  11. #41
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    Quote Originally Posted by Cody Colston View Post
    Scott,

    I realize the topical treatment will kill the PPB's as they bore out of the wood but what about the eggs that they leave behind? Also, I believe that PPBs can incubate for years before hatching. How long do borate treatments last?

    I treat my lumber with Timbor immediately after sawing, as I sticker and stack it. The lumber is already wet. Can additional wetting of the surface cause surface checking? I've not really noticed it if it can/does.
    The borate won't kill the eggs, but when the larvae hatches (1 - 2 year typical gestation cycle) they will ingest the borate as they bore out of the lumber, killing them and ending the cycle. Unfortunately sometimes they stay inside the wood for several years before they bore to the surface, which is one of the reasons why heat is the best method for PPB treatment. Heat kills everything - eggs, larvae, and adult beetles.

    Unless exposed to water, borate treatments will stay in the lumber basically forever (however there is a caveat to this which I will explain in the next paragraph). They can leach out if they are in a stack of lumber that is stored outdoors (or in outdoor furniture), or on posts, RR ties, fence rails, etc that are exposed to rain.

    Applying Timbor immediately after sawing is the best application method because the moisture already existing in the lumber helps to wick the borate solution deeper into the wood. It's best if you keep the surface saturated for 10 minutes or so to encourage maximum absorption. Depth of penetration is important since it's the residual effect that you're after. When you spray dry, rough sawn lumber the treatment probably won't go much deeper than 1/16". Unfortunately (and this is the caveat), typically at least 1/8" is planed off of each side of a rough sawn board, effectively removing all of the residual borate treatment and reducing the effectiveness of treatment. Lumber treated green has a deeper penetration rate.

    Additional wetting of the lumber can definitely cause surface checking. This is easily observed if you stack and sticker a pile of lumber outdoors w/o cover. Over time you will notice that the upper layer becomes highly surface checked, but the layers underneath are much less so. This is because of rain rewetting the upper layer boards after they have started to dry.

    There is an entire chapter in the FPL Air Drying of Lumber manual that addresses decay, including surface checks due to rewetting. The amount of checking is directly proportional to the amount of water absorbed by the lumber.

  12. #42
    Quote Originally Posted by Scott T Smith View Post
    The borate won't kill the eggs, but when the larvae hatches (1 - 2 year typical gestation cycle) they will ingest the borate as they bore out of the lumber, killing them and ending the cycle. .

    End the cycle? Who cares? What you want to end is the life of the eggs & larvae currently inside your wood. They can stay in there for up to (IIRC) FIVE YEARS, during which time they do massive damage. Do you really want to wait until they emerge to kill them?


    Bora Care goes fully into the lumber, due to its glycol content, thus killing everything within a day or so. It also is much less prone to leeching out, again due to the glycol's ability to actually penetrate the wood cells. Bora Care costs more, and it's harder to make at home, but it's kind of a no-brainer for already-exposed lumber.
    Last edited by Allan Speers; 07-10-2015 at 11:38 PM.

  13. #43
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    Thanks for all the tips. It sounds like that fumigation method is the simplest, and probably cheapest method. I just wonder if it gets deep enough into the wood. It sounds like the Bora Care shjould fully penetrate into the wood. What happens when you plane that stuff? Does it put some toxins in the air?
    Will I need to unstack my whole pile to apply the bora care to each individual board, or can I just reach in between the stickers with a pump sprayer?

    This is such a bummer - with all the research I did into turning the tree in my yard into lumber, having a portable mill come to my house, and stickering it properly - I never thought about an infestation. I have two rather large piles of wood. I have just started to use it more and more. I actually just finished a dining room table. Luckily I had pulled the wood for the table a while ago - and it had been sitting in my shop.

    As for the heat treating - that sounds good, but I don't know if there are any kilns around here, and I don't think I have the resources to move all that wood either. Heat treating myself sounds like it could be a good solution. I'll have to look into that option. I also keep honeybees - and their hives are not far from the piles of wood - maybe 50' away? I would worry about any chemical treatment nearby killing my bees.

  14. #44
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    Quote Originally Posted by Allan Speers View Post
    End the cycle? Who cares? What you want to end is the life of the eggs & larvae currently inside your wood. They can stay in there for up to (IIRC) FIVE YEARS, during which time they do massive damage. Do you really want to wait until they emerge to kill them?
    Allan,

    I concur with you that a Bora Care type solution is the best method for treating already dry log cabin logs or timbers, etc that are not practical to place in a kiln, and I really enjoyed your posts about the homemade "boracare" solution and downloaded it for my records. It was extremely informative and well written. Thank you very much for putting that together and sharing it with us.

    I think that you are misinterpreting my "explanation" to Cody as a "recommendation" though. Cody and I are both mill operators and work primarily with green lumber (which does not require glycol to wick the Timbor solution into the wood). Cody's post (which I was specifically answering) even references working with green lumber.

    If you will go back and reread my posts you will discern that my preferred method of sterilizing lumber is heat. This is the only process approved by every lumber related sanctioning body. Timbor, Boracare, or any other boric acid or fumigation based method is not approved by every org, and as you know there are tradeoffs. I am not a supporter of rewetting already dry lumber, especially fine furniture lumber, due to the potential for surface checking to develop. I am also not a fan of using chemical solutions as the first choice when heat sterilization is well proven and leaves no toxic (or other type of) byproducts. Yes, chemical solutions do have their place.

    I personally only use a 15% Timbor solution to treat freshly milled (green) thick slabs and timberframe timbers as an insect retardant during the air drying process. All slabs and most timbers are subsequently heat sterilized in one of my kilns after they have completed the air drying process.

    Respectfully,

    Scott

  15. #45
    Understood, Scott, and yes that all makes sense.

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