Accurately measure when using small quantities of dry pesticides

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By David Harrison

  Backpack and handheld sprayers are often used around the farm or home to treat small areas. However, most pesticide labels focus on mixing and applying pesticide in quantities that far exceed the sizes of common backpack and handheld sprayers.

As a result, accurate conversions must be made to avoid a spray mix or application rate that could result in a treatment that is either stronger than recommended or too weak to be effective.

Two factors influence the accuracy of conversions: properly measuring pesticides (especially dry pesticides) to be added to the mix, and applying the correct amount of that pesticide for the desired outcome.

The rates for liquid pesticides tend to be easy to convert from large to small quantities because they can be measured in common units such as fluid ounces, tablespoons, teaspoons, or milliliters. However, dry chemicals are difficult to measure without accurate scales, which most farmers and homeowners do not have.

UK Extension publication HO-83, Dry Pesticide Rates for Hand-held Sprayers is available at the Extension office and on the web to help determine proper application with small sprayers.

Here are some helpful hints when using the publication: 1) Make sure the pesticide concentration and formulation you are using exactly matches those found in the publication, 2) Some of the pesticides may be out of circulation or may be found in various formulations, 3) If a pesticide is available in more than one dry formulation, do not assume the values presented for one formulation are applicable to all, 4) Values are presented in teaspoons for one- and three-gallon, and in tablespoons for five-gallon whenever possible. In some instances where the rate is high, resulting in large teaspoon values, the numbers have been converted to cups, and 5) Reminder: one cup is equal to 16 tablespoons or 48 teaspoons.