Plant care products such as pesticides, seeds, and chemicals must be applied properly. Failure to do so risks harming the operator, the environment, and the host plant. Furthermore, improper application may be illegal if it is in violation of a label.

Once a pesticide, pesticide, or other product is selected for application, two numbers must be known: the application rate and the size of the area to be treated, application rate. Calibration is a continuous procedure that must be regularly performed by the pesticide applicator.

Equipment calibration is the final step prior to applying the product. Calibration is adjusting application equipment so it delivers the correct amount of product. Calibration is critical because there is often a thin line between the rate at which a product will perform as directed and the rate at which damage occurs.



Determining the size of treatment area is not difficult if you break the area into known shapes: circles, rectangles, and triangles. Applying basic formulas for those shapes enables the area to be readily determined.

The treatment area is usually expressed in terms of square feet. Farmers usually use acres as their standard of measurement but expressing urban landscapes in terms of acres is not practical in most situations.

Determining Square Footage: A Few Formulas

Squares and Rectangles

Area = Length x Width


Length = 50 feet

Width = 30 feet

Area = 50 feet x 30 feet = 1500 square feet



Area = .5 x Base x Height


Base = 40 feet

Height = 80 feet

Area =  .5 x 40 feet x 80 feet = 1,600 square feet


Area = π  x radius2

(π = 3.14)

A circle is a shape with all points the same distance from its center.
The distance across a circle through the center is called the diameter. A real-world example of diameter is a 9-inch plate.
The radius of a circle is the distance from the center of a circle to any point on the circle. If you place two radii end-to-end in a circle, you would have the same length as one diameter. Thus, the diameter of a circle is twice as long as the radius.



r (radius) = 20 feet

Area = 3.14 x (20 feet x 20 feet) = 1,256 square feet


Determining Square Footage of Irregular Areas

Divide area into smaller sections having familiar shapes

Area = sum of areas of the familiar shapes


Determining Square Footage of a Suburban Yard

If a lot is 126 feet deep and 105 feet wide, simply multiply 126 by 105 for a total of 13,230 square feet. Next, subtract the square footage of the house footprint, driveway, and other areas not to be amended from the total area. The remainder will be the square footage of the yard area.

Size of the Green Surface to be Treated:

Total Lot = 13,230 square feet (126 feet times 105 feet)


House = 1,040 square feet

Deck = 144 square feet

Drive = 480 square feet


ANSWER = 11,566 square feet