Section II. PESTICIDE MIXING CALCULATIONS
IMPORTANCE OF ACCURATE CALCULATIONS
It is difficult to overemphasize the importance of making accurate calculations
each time a pesticide is mixed. There are several reasons for emphasizing this
a. Safety. If a formulation is prepared with too high a working concentration,
human lives and other nontarget organisms may be endangered.
b. Effectiveness. If a formulation has too low a working concentration, the
control program may be a failure and insects may develop resistance to the pesticide.
In addition, a repeat application may be necessary, thereby increasing the total
exposure to humans and other nontarget animals.
Economy. Pesticide concentrates are expensive. If calculations in mixing
are not precise, not only do we run the risks cited in paragraphs a and b above, but we
also may needlessly waste toxic materials. Although the cost may not be great for any
one given error, the cumulative expense due to error may be enormous on an Army-
2-10. WEIGHT/WEIGHT OR VOLUME/VOLUME CALCULATIONS
a. General. If we were mixing pure technical grade toxicants with diluents,
mixing problems would be simple. We would merely have to mix, for example, 2
pounds of toxicant with 98 pounds of diluent (or 2 gallons with 98 gallons) to obtain a 2
percent mixture. In practice, however, our calculations are never quite so simple. We
are not necessarily mixing 100 pound or 100-gallon quantities, and our concentrates are
never 100 percent pure. Therefore, we use formulas that simplify our work as much as
possible. In order to use the formula, there are certain basic elements of information we
must have. The following must be obtained from the pesticide label:
(1) The name of the active ingredient (toxicant), its concentration, and its
form (carbaryl, 80% powder; malathion, 95% solution concentrate; etc.).
(2) The type formulation to be prepared (dust solution, emulsion, etc.) and
the diluent to be used.
(3) The concentration of toxicant desired in the final formulation (1%, 2%,
(4) The quantity of final formulation required (5 gallons, 100 pounds, etc.).