COURSE Borates and the Facts About Wood (1).pptx

1. Borates & the Facts About Wood
Assured Control with a Margin of Safety
Borates are naturally-occurring insecticides and fungicides. In fact, products formulated from borates, cannot be
synthesized or manufactured like conventional pesticides. Instead, borate insecticides and fungicides are derived from
scarce mineral deposits found chiefly in the western United States. Boron is one of the 109 elements on the chemist's
Periodic Table of Elements. Too reactive to exist in its pure form in nature, boron is found in mineral deposits as a
crystalline group of "borates" (oxides of boron), that include boric acid, borax and others. As one of the earth's elements, it
is not surprising that small amounts of boron, in the form of borates, are found in the soil, sea, plants and animals. All the
roles that borates play in nature have not been discovered. However, biologists know that borates are an essential
micronutrient for plant life and also play an important nutritional role in animal life. Researchers are currently trying to
determine if borates play an essential role in human life. Borate chemical properties are used in many commercial and
industrial applications. Borates are used in the production of products as diverse as detergents, cosmetics, medicines,
flame retardants, hydraulic fluids, fiberglass insulation, microelectronics, fertilizers, ceramics and glass.
Borate use in Pest Control
When and how borates were first used in pest control is not documented. It is possible that borate miners in the 1800s
may have discovered that they did not suffer from the flea and lice infestations so common at the time. What is known is
that borates have been used for more than 100 years to control pests. One advertisement from the 1880s promoted a
formulated borate cockroach bait product. By the 1940s borate formulations were being used to protect wood. Because
they are water-soluble, borates will diffuse into wood using the wood's own moisture. Once diffused into the wood, borates
protect against termites, wood destroying beetles, carpenter ants, fungi and other wood destroying organisms. This
protection can last for decades because borates are inorganic compounds that do not break-down boron was introduced
in the United States in 1991 by U.S. Borax, the world leader in borate technology. The product's introduction into the
United States follows more than 40 years of successful use to protect wood in Europe, Australia and New Zealand.
Boron has a proven Mode of Action
Borates have long been known to be slow-acting stomach poisons to insects and a contact poison to wood destroying
fungi. Borates are not directly lethal to an organism. Rather, they inhibit necessary oxidative metabolic activity at the
cellular level - a constant energy-producing process necessary for life. Over time, inhibition of fundamental biochemical
activity results in death. Because the mode of action is fundamental, borate efficacy is absolute and effective against a
broad spectrum of pests. Importantly, this fundamental mode of action also means that development of insect resistance
to borates is virtually impossible.
Human Margin of Safety
While highly effective against insects and fungi, borates provide a significant margin of safety for humans. While the mode
of action is the same for all living cells, human exposure to borates from pest control applications simply does not pose a
significant risk for several reasons:
 Human exposure levels from pest control applications are insignificant in comparison to insect dosage levels
because humans are physically so many times larger than insects.
 Borate exposure is further limited in humans because of the way human bodies efficiently eliminate borates. In
humans, any elevated exposure to borates is rapidly processed by the kidneys and eliminated through urination.
 Chronic borate exposure is limited because borates do not bioaccumulate in humans or other mammals.
 Borate exposure is limited because borates are not absorbed through intact skin.
 Borate mammalian toxicity is relatively low. Disodium octaborate tetrahydrate has an acute oral LD50 of 2,550
mg/kg in rats, an acute dermal LD50 of greater than 2,000 mg/kg in rabbits, and an acute inhalation toxicity
(LC50) of 2.0 mg/h in rats.
In conclusion, borate insecticides provide a margin of safety for humans but are lethal to insects because insects are
exposed to a much greater dose in relation to their body size and weight. The primary exposure route for insects -
ingestion from eating treated wood or by grooming -provides a lethal dose, and insects can also be exposed through
direct contact and absorption through their body wall. Once ingested, insects cannot eliminate borates from their bodies in
the way humans can. Borates are a contact poison to wood destroying fungi. The mode of action is the same as with

2. insects, but fungi do not ingest the borates like insects. Instead, a treated wood environment puts fungi constantly and
directly in contact with the lethal borate.
Borate environmental profile
Borate use in pest control poses a low risk to the environment. While an essential micronutrient to plants, an excessive
dosage of borates can be phytotoxic to trees, shrubs and other plants around or in a structure. If a borate solution is
accidentally sprayed on plants, the plants and surrounding area should be washed down with plenty of water to dilute the
borates. Borates have a low toxicity to fish. The LC50 for trout is 350 ml/L. However, care must be taken to keep boron
applications or overspray from any body of water. Borate applications to wood do not result in airborne residues.
Using Boron to Control Wood-Destroying Organisms
In the past, different pesticide formulations and active ingredients have been used for control of wood-destroying
organisms (WDOs), beetles, decay fungi and termites above ground. These products often presented problems. Some
had strong odors, none penetrated wood well and the effective residual life was short. Fumigation, while still required in
many cases, is expensive and provides no residual protection against reinfestation. Boron Insecticide is a product that can
effectively solve many of these problems. It is easy to mix and apply and has no odor. Its residual life is indefinite if the
treated wood is protected from running water. Boron penetrates far better than do other residual insecticides used to
control wood-boring insects. In order to understand the potential for attack on wood by insects and fungi, it is necessary to
become familiar with the relative importance of the specific classes and parts of wood, and the moisture in the wood. This
understanding will also provide information on how boron penetrates wood.
Two types of wood
There are two types of wood, hardwoods and softwoods. Hardwoods come from trees that have leaves: oaks, maples or
walnut, etc. and softwoods come from trees having needles: the pines, firs and spruces.
When alive, the wood directly under the bark that is involved in the movement of sap is called sapwood. The wood in the
center of the tree is often darker in color, and is called heartwood. Generally the sapwood and early wood are the target of
insect attack. Stored products in wood cells attract beetles and termites attack early wood. Heartwood, however, has
stopped functioning in the movement of sap, and has had a number of substances deposited in it, which also impart
resistance to attack by insects and decay fungi. It is often more resistant to the movement of water and is more difficult to
penetrate with insecticides.
Wood moisture levels
When freshly cut logs are processed into usable lengths of wood, the wood then used in construction is kiln dried, having
moisture levels of 15% or less. However, while wood is in storage or after it is in use, it slowly reacts to the moisture in the
air around it and assumes equilibrium moisture.
 A. Cambium - living cells that form new wood
 B. Outer bark - dead, protective layer
 C. Inner bark - living: transports food from the leaves
 D. Sapwood - living and dead cells: transports sap and stores food
 E. Heartwood - inactive, dead cells containing extractives
 F. Pith - spongy center of original stem
 G. Wood ray - cells which move sap across the grain
 H. Annual growth ring - early - and latewood produced in one year
There are many factors that influence the final moisture level reached. Also,
within structures the levels may vary during the year. Such things as ventilation,
drainage, heating and air conditioning, humidity and condensation, etc.,
influence moisture content of the building and, therefore, of its wood. In addition,
wood-boring organisms attacking structural wood are often dependent on
relatively high moisture contents to initiate attack and in some cases, to continue
their attack on the wood. Termites will attack "dry" wood but bring moisture into
the wood. Wood decay fungi need even higher moisture contents to begin their

3. attack. That will continue as the wood becomes wetter until the cell cavities are filled with water.
The moisture needs of these organisms are important to understand, since the wood moisture content will affect the rate
and depth to which boron will diffuse into wood. At low moisture contents, some diffusion will occur, but surface amounts
of borate are extremely high. However, treating wood with a high moisture content means that boron will diffuse deeply
into the wood to protect against or eliminate WDOs.
Subterranean termites
Subterranean termites, the insect that causes the greatest amount of damage to
structural wood in the U.S., will damage both hardwoods and softwoods. It is typical of
subterranean termites to consume the softer early wood first, leaving the layered
appearance in the damaged wood. The initial damage begins on the wood surface,
but termites can tunnel and produce galleries throughout the wood. In larger
dimensioned timbers, these tunnels or galleries can penetrate deeply into the wood.
While destroying wood, termites also increase the moisture content of wood in which
they are feeding. In some instances, subterranean termites may find a moisture
source above ground and survive without any contact with the soil. In these cases the usual soil treatment will not solve
the problem, or control can be delayed for months. Locating and eliminating the moisture source is critical for control.
Even if the termites are controlled by treatment, wood decay can take over and continue to destroy any of the wet wood.
Termites enter the wood from the surface, so the first target treatment area for application is the surface. If an infestation
is already present in the wood, the higher moisture content should increase the movement of the boron. Boron treatment
will control both termites and wood decay even when alternative moisture sources are available. However, elimination of
the moisture source is recommended in any case.
Drywood termites
Drywood termites feed internally in both hardwoods and softwoods and can survive in wood that is quite dry (3%). Again,
these insects enter from the surface so even though the wood they attack is fairly dry, boron on the surface will prevent
initial attack. In established infestations, Boron can be injected into the termite galleries or the wood itself to obtain control.
Dampwood termites
Dampwood termites require no ground contact, but attack wood with a high moisture content and often coexist with wood
decay. These termites can be controlled by spraying or brushing wood with boron because the high moisture level in the
wood enhances Boron penetration.
Powderpost beetles
There are two types of powderpost beetle that attack wood in structures. The lyctid powderpost beetle, sometimes called
true powderpost beetle, will attack the earlywood of certain hardwoods. Their eggs are
laid in rather large pores (wood cells) in the earlywood and the larvae tunnel directly
into the surrounding wood. This means that their attack will usually be rather scattered
and damage is restricted to particular parts of the wood. As the larvae complete
development and prepare for emergence as adult beetles to the outside, they tunnel
close to the surface of the wood. Lyctids may attack wood that is quite dry but a surface
Boron treatment will deposit high amounts of borate and thereby prevent initial attack
and kill any larvae feeding just beneath the surface.
The other type of powderpost beetle, the anobiid, will attack both hardwoods and softwoods that have higher moisture
content than normal. There is variation among the anobiid species, but they tend to be problems primarily in damp, poorly
ventilated crawl spaces. The eggs are laid on the wood surface and the larvae bore directly into the wood. They usually
tunnel within the sapwood and only occasionally into heartwood. As the larvae mature, they also tunnel back to the
surface in preparation for the emergence as adults. Applications of Boron protect the surface of the wood and stop larvae
from entering the surface of the wood. The higher moisture level enables the borate to
penetrate and kill larvae in the wood.

4. Old house borers
Old house borers are found in the sapwood of softwoods. The eggs are laid in cracks in the wood surface and the larvae
bore into the wood below. The old house borer only requires 10% moisture to infest wood, so they may be found in wood
in drier parts of buildings. They may bore deeply within large timbers, but frequently they tunnel quite near the surface.
Again, surface treatment with boron will stop initial infestation and kill larvae tunneling near the surface.
Carpenter ants
Carpenter ants construct nests in hardwoods and softwoods, but do not consume the excavated wood. Though they
usually start their nests in damp wood, they can extend their galleries into dry areas. In addition, they sometimes form
satellite nests in wood that is no wetter than the surrounding structural members. Because of their habit of moving from
outdoor infestations to indoor locations, they crawl over wood surfaces that they have not attacked. This makes them
susceptible to picking up boron dust that has been applied outside their nest galleries. As they groom themselves, they
take insecticide into their stomachs and are poisoned.
In addition, since they often start their attack on the wood surface, boron solution applications to the surface have proven
very effective at preventing carpenter ant penetration.
Decay fungi
The common Brown and White rot fungi require wood moisture of 25% or more to maintain an infestation and to destroy
the wood. Their destruction is internal and only in later stages of development will you see the fungus growing on the
wood surface. Boron is a contact poison to these organisms. Surface treatments will protect the wood against attack. If
already under attack, the high moisture will allow the boron to penetrate deeply into the wood, to the source of the
problem. (One strain of fungi, Poria Incrassata has water-conducting strands that carry water from soil into building
elements.)
Wood Facts and Fictions
Dry rot.
There really is no such thing as dry rot. Wood needs 4 things to decay: water, oxygen, food (wood) and favorable
temperature (40F - 105F). Keep wood below 22% MC and you are generally safe.
Rot is catchy.
Only when conditions are right will the infection develop into rot. The moisture content (MC) of wood needs to be above
28% to be initially infected. Since all lumber is above 28% MC at some point in its life, all lumber is infected. When the MC
of wood drops below 22% the rot fungi goes dormant. It’s harmless, but it will be reactivated when the MC rises above
22%. The solution is: keep wood dry or treat it with Boron.
Pressure treated lumber is resistant to attack by termites and carpenter ants.
This assumption is half true. Termites that eat treated lumber will die. However, termites may also decide to tube around
CCA (Chromated copper arsenate) treated wood and survive to enjoy the more delicate studs and joists that lay beyond
the poisoned barrier. Arsenical treatments do not repel or kill carpenter ants. (In 2003 the EPA and the lumber industry
agreed to discontinue the use of CCA treated wood.)
Ants are attracted to wet and decayed wood because it is soft and weak. It is easy to chew. That’s why ants like foam
insulation. Ants don’t ingest wood, they simply hollow out wood and nest in it. Wood that is treated with borates is a
different story. Borates are very soluble and can be picked up by ants as they work their way through borate-treated
wood. The borates are ingested when ants groom themselves. They are poisoned at this point.

5. The use of trade names in this publication is solely for the purpose of providing specific information.
American Pest CEUS does not guarantee or warranty the products named, and references to them in
this publication do not signify our approval to the exclusion of other products of suitable composition.
All chemicals should be used in accordance with directions on the manufacturer's label. Use
pesticides safely. Read and follow directions on the manufacturer's label.