Expert response:

Herbicides are a lot different than other chemical concentrates as the rates you use are not based per gallon of water but per area as water is just the carrier and will vary from person to person due to equipment used and walking speed. The rate used depends on the type of turfgrass you have as well as the program you are following (single application or split) We do recommend calibrating your sprayer if you do not know how much water it takes you to cover the target area to ensure correct application. You would calibrate by determining the volume of water required to treat 1,000 square feet. Use this calibration volume to determine the amount of water and Prodiamine 65 WDG herbicide needed to treat the target area (see the following calibration example). Note: Sprayer calibration (volume of spray needed to treat 1,000 square feet) will vary with each individual operator. Steps in Calibration: 1. Mark an area of 1,000 square feet (i.e. 20 by 50 feet or 25 by 40 feet). 2. Place the sprayer on a level surface and add water noting the final level of water in the spray tank. 3. Spray the marked area with a sufficient volume of water to provide uniform coverage. Refill the sprayer to the same level as before measuring the amount of water added. The measured water added to the sprayer is the volume needed to cover 1,000 square feet. 4. Determine the application rate (fl. oz./1,000 sq. ft.) for Prodiamine 65 WDG from the Recommendations section of this label. 5. To each volume of water used as measured in step 3, add the amount of Prodiamine 65 WDG as determined in step 4. Example: If the sprayer uses 2 gallons of water to cover 1,000 square feet and the desired application rate of Prodiamine 65 WDG is 0.185 - 0.055 oz/1,000 square feet, then you would add 0.185 - 0.055 oz of Prodiamine 65 WDG to every 2 gallons of water to be used."