rotten to sound wood is abrupt; they are least effective in Douglas-fir with
poorly defined rot pockets. For Douglas-fir, use a fumigant alone or in
combination with a water-soluble preservative solution. To arrest internal
decay, water-soluble chemicals, e.g. arsenicals, fluorides or borates are
forced into the voids and diffused through the wet wood. Ants in pole voids
can be controlled by injection with volatile liquids combined with preserv-
atives such as creosote or pentachlorophenol.
Serviceable poles with voids, hollows or insect galleries can be internally
treated with a liquid pesticide registered by the EPA for such use. Poles
shall be bored with a 3/8 inch drill bit, a sufficient number of times to assure
uniform internal coverage. Preservatives are pumped into the bottom hole
until it runs out the next higher hole. The hole is then plugged with a
preservative-treated plug, and preservative is then pumped into the next
higher hole until it runs out the hole above. This procedure is repeated
until the entire cavity is flooded or a maximum of one gallon of preservative
is used. Preservative pastes also can be injected into holes to treat internal
Because of the hazards associated
with fumigants, they shall only be
applied by individuals who hold a valid
DoD or State Pesticide Applicator
certification In the Category applicable
Consult the cognizant PMC for local regulations concerning fumigants.
Fumigants can control internal decay for at least nine years. As a result,
the use of fumigants is now common technology.
Sodium N-methyl dithiocarbamate (Vapam), methylisothiocyanate
(MITC-Fume) (Vorlex), and tricholoronitromethane (chloropicrin) are
currently registered with the U.S. Environmental Protection Agency
(EPA) for application to wood.
Label directions for applications of individual fumigants must be followed.
In general, starting at the ground line, 5/8 to 7/8 inch diameter holes are
drilled directly towards the center of the pole at a steep downward angle.