Compare the total costs of a conventional pest management program with the
costs of an IPM program. Instead of routinely spraying pesticides, IPM employs
monitoring to determine the location, extent, and the cause of a weed or pest prob-
lem, and then applies a variety of non-chemical or least-toxic pesticide controls. IPM
strategies are more effective because they are better able to prevent pest troubles. This
is because they focus on modifying the cause of the dilemma, instead of just spraying
the pest after it becomes a problem. IPM is the equivalent of a wellness program to
maintain the facility and landscape in a healthy condition to avoid the need for spe-
cific chemical treatments and the costly side effects that can be associated with them.
Pesticides are used only after other options have been fully considered and only if
other methods have not reduced pests to tolerable levels. Determination of this toler-
ance level is based on pest-specific and site-specific criteria.^17
Least-Toxic IPM
Least-toxic IPM decision making seeks to manage pests through prevention. It is
based on the fact that pests almost always can be managed without toxic chemicals.
Prevention is the first line of defense. Modification of pest habitats (such as putting
vegetation-free buffer zones alongside buildings) deters pests and minimizes infestation.
IPM requires extensive knowledge about pests, such as information about infestation
thresholds, life cycles, environmental considerations, and natural enemies. Pest monitor-
ing is critical to identify existing pest problems and areas of potential concern, as well
as to determine how decisions and practices may impact future pest populations. Moni-
toring must be ongoing to prevent small pest problems easily controlled with least-toxic
means from becoming infestations. Threshold tolerance levels of pest populations are
established to guide decisions about when pests pose a problem sufficient to warrant
some level of treatment. If treatment is necessary, non-chemical means are given prior-
ity. Traps and enclosed baits, beneficial organisms, freezing and flame or heat treat-
ments, among others, are all examples of non-chemical or least-toxic pest treatment
methods. A good IPM program prohibits the use of known and probable carcinogens,
reproductive or developmental toxins, endocrine disrupters, cholinesterase-inhibiting
nerve toxins, and the most acutely toxic pesticides.
In sum, least-toxic IPM establishes a hierarchy of appropriate pest management strat-
egies, with monitoring and prevention at the top and toxic pesticides at the bottom.
Least-toxic IPM never provides all available pest control methods equal consideration.
It always favors non-toxic alternatives. Beware of alleged IPM policies that allow the
use of chemical pesticides without prior exhaustion of all other means of control.^18
Least-Toxic Approaches Are Cost-effective
Preliminary indications from IPM programs in school systems suggest that long-
term costs of IPM may be less than those of conventional pest control methods. By
focusing on prevention and monitoring whenever pests are a problem, school IPM
Pesticides in Schools | 123