The best treatment appears to be a boron/boric acid based product.
http://www.growinglifestyle.com.au/article/s0/a114043.html
suggests a product (referenced other places as well) called Boracare:
"The best product for this wood treatment is Bora-Care. Boracare is
an
odorless, boron based material that is mixed with water and applied to
the wood by brush or a hand held pump sprayer."
Also, methyl bromide can be used,
http://www.cdpr.ca.gov/docs/dprdocs/methbrom/mb4chg.htm
"Methyl bromide also has been used historically for structural insect
control; however, its use has been declining in recent years as
alternatives became available. The exception is powderpost beetle
eggs, where methyl bromide is still the most cost-effective means of
control."
To speak directly to neem oil and powderpost beetles,
From: http://www.mastergardeners.org/tips/sept.html#neem
"Neem Oil - Neem oil was approved in California a few years ago for
use on ornamental plants. I first heard of neem oil while reading
about a study they did in another state testing a popular fungicide
against our favorite standby horticulture oil and baking soda, and
neem oil and baking soda for mildew. The neem oil came in a close
second to the fungicide. I wondered, "What is neem oil and why haven't
I seen it anywhere?" It hadn't been approved yet. It is derived from
the neem tree. It's low toxicity to mammals and lack of persistence in
the environment make it a biorational pesticide. Aphids, caterpillars,
loopers, mealy bugs, thrips, whiteflies, and diseases like mildew and
rust are effectively controlled. Its main function on insects is to
inhibit the insects growth, so they don't reach adulthood. It is
somewhat effective against adults by preventing them from feeding. It
also acts as a repellent. It is most effective when alternated with
insecticidal soap or pyrethrin. This gives you a one two punch, by
killing the insects in different stages of development. Follow label
instructions. Spray 2 or 3 times every 7 to 10 days." |
