February 1994

Formulation and Sprayer Calibration

David M. Kopec, Extension Turfgrass Specialist

Golf courses usually require periodic application of either fertilizers or plant protectant agents for adequate turf growth and performance. A particular product may come in various types of FORMULATION, that is for example, some liquid or dry form. The FORMULATION of the product has some relationship as to how you determine how much product to apply at the label rate.

For example, the active ingredient in a herbicide may be expressed as lbs. of active ingredient per gallon of product, or as a percentage of the product by weight. This is a result of the type of FORMULATION the product is packaged in.

Most liquid products are formulated as an emulsifiable concentrate. The letters "E" or "EC" will appear on the label followed by the lbs. of active ingredient/per gallon of product. For example, a 4 EC of herbicide -A-, means that 4 lbs. of the active ingredient is present in one gallon of the product. A 1/2 gallon container would contain 2 lbs. of the active ingredient, and a 1 quart container would have 1.0 lb. of active ingredient. Other typical examples of liquid concentration for "E" or "EC" products would a 1.5 EC (1.5 lbs. of the active ingredient/gallon of product) 3.5 EC (3.5 lbs. of the active ingredient/gallon of product).

Dry formulation products take on an active ingredient concentration as percent by weight (just like a granular fertilizer). The type of dry matter that the active ingredient and the carrier (non active-filler) are made of, determines the exact FORMULATION type. For example a 50W is a wettable powder product which is 50% active ingredient by weight. So a 1 lb. bag is 1/2 lbs. of the active ingredient. A 5 lb. bag contains 2.5 lbs. active ingredient, etc. Other typical concentrations of wettable powder products are 20W, 50W, 70W, 15W, etc. Remember, the number in front of the W represents the percent of active ingredient, by weight.

A new formulation is a water soluble packet (WSP). This is a pre-weighed soluble powder which is in a self-sealed wrapper for safety in storing, handling, and mixing. The proper number of packets are dropped in the spray tank to achieve the proper active ingredient concentration. The WSP products usually contain directions on the number of pre-weighed packets to cover either 1000 ft2 or 1 acre of turf. You should, however, look for the fine print which should tell you the active ingredient concentration of the product. For example, a 5 ounce packet of a WSP (which is 50% active ingredient) contains 2.5 ounces of active ingredient, per packet.

Examples of pesticide formulations and units of measure are listed below:
Formulation Symbol Active Ingredient AI 

and measure units

Granular G percent weight of product Dry granules of pesticide mixed with a carrier (clay, corncobs vermiculite). 

Apply with granular spreader.


concentrate (liquid)

E or EC pound AI per gallon Oil soluble pesticide (active) with emulsifying agent, so it can be mixed in water.
Wettable powder (fine powder) W or WP percent weight of product Dry powder of pesticide mixed with clay or talc filler. Usually needs continuous agitation in tank.
Flowable Suspension F pounds AI per gallon Wettable powders suspended in water. Minimizes 'powder type' exposure. May require agitation.
Soluble Powder SP percent weight of product Active ingredient on a dry salt.
Wettable Dispensable Granule WDG percent weight of product Essentially a pelletized form of a wettable powder or granular carrier which will mix easily in water.
Water Soluble Packet WSP percent weight of product Wettable powder pre-weighed in water dissolvable packet.

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