Measuring and Diluting

Maggie Scarbrough

Measuring pesticides accurately is also important. When you don’t take the time to do this right, it is easy to under- or overdose. Use graduated utensils and for dry formulations, use a scale. If you measure a diluent or a liquid, use: measuring spoons or a “tip and pour” to measure teaspoon and tablespoon amounts; use graduated measuring cup or a “tip and pour” to measure 1/4 cup up to one pint; use a graduated pail or jug to measure one pint to five gallons; use a flow meter for amounts more than five gallons.


Never approximate or add a little more to cover an amount. Also do not assume that a tank or container holds the exact amount it specifies. Test it to be sure. Either use a container that you know is accurately marked to fill the tank or use a flow meter and a hose. Mark the measure amounts on a dipstick or sight gauge.


When you use water or other liquid to dilute the concentrate, rinse any measuring utensils three times. Rinse them with diluent and put the rinsate into the mix tank. Never use these utensils for any other purpose and be sure they are thoroughly cleaned after each use.


If you use a ready-to-use formulation, measure it carefully as it is difficult to return to the container.


Some pesticides are sold in formulations that are ready to be used. They are dilute formulations and are considered RTUs (ready-to-use). A lot of pesticides are sold in a concentrated formula that requires dilution before use. If you were to use these pesticides without diluting them, significant harm could be caused. Whoever dilutes these products must do so carefully and accurately.


The most common diluent is water. Some others that are used are kerosene or oil. For dry ingredients, powders or cornhusks are sometimes used. When diluting, the formulation is either mixed in a mix tank or put into the application equipment and mixed.


Check pesticide labeling for: what to use as a diluent, how much to dilute the formulation and for how much of the diluted pesticide to apply.


You will also need to calculate how much pesticide and diluent you have to combine to get the correct amount of mixture for your equipment. You may need to know how much your equipment holds, how much mixture needed for the job, how much mixture your equipment applies per area, or the size of the site.


There are guides available that can help with examples for your calculations. The pesticide label may offer examples, but unless the situations are the same you will have to make calculations yourself.


Simple measurements and formulas will allow you to determine the size of your application area. Rectangles, circles and triangles require simple measurement. For irregular shapes, reduce them to combinations of rectangles, circles and triangles then add those measurements together. If you have to use a fumigant, you will need to know the volume of the enclosed space you are treating. For treating a body of water, you will have to know the volume of the water. For those that have an irregular shape, calculate parts and add them together.