If you are one of the many turf managers who use a truck-mounted water tank with a walk-along technician carrying a spray gun to apply turf herbicide, you?EUR??,,????'???ll want to read these tips to make sure you apply the optimum amount of chemical to your turf area.

To apply herbicides, most turf managers get the best truck they can afford and recruit the best employees?EUR??,,????'??+they even get them certified?EUR??,,????'??+but ultimately good herbicide application depends on proper calibration of both truck and the walking speed of the technician. It?EUR??,,????'???s those two factors that determine whether you get a beautiful weedless yard or end up with spots. If you under apply, then you?EUR??,,????'???re going to have tougher weeds that cannot be controlled. If you over apply, then what you are doing is wasting chemical, which comes directly out of your profit. And if you drastically overspray, you can damage the turf.

Calibrating Your Truck

Before we start interpreting the small print on those pesky herbicide labels, lets focus on calibrating your truck and your lawn gun.

For the sake of argument, lets say you want your sprayer to apply two gallons of water per minute, which is the rate many people in the industry use. You?EUR??,,????'???ll need to crank up your truck, fill the tank with about five gallons of water and make sure that your spray gun has the right screw on tip that puts out two gallons of liquid per minute. Then get a five-gallon bucket and spray in that bucket for one minute. When the minute is up, if you have sprayed three gallons into the bucket, then you are applying more water than you want, so reduce the pressure and spray test again until you get two gallons per minute in your bucket. Now you can rest assured that your truck is calibrated to apply two gallons per minute.

Calibrating Your Technician

Next you?EUR??,,????'???ll need to calibrate your walk-beside spray technician to spray at the same two gallons per minute rate as your truck. To do this, mark a 1,000-square-foot area (preferably on pavement) and have the technician walk and spray across the area while you time them. If it takes them two minutes to walk the area, they just used four gallons of water (remember?EUR??,,????'??+you?EUR??,,????'???ve set the truck to spray two gallons per minute). You want your spray technician to walk the area in exactly one minute, so they will need to increase their walking speed until they can consistently be timed to finish the area in one minute while properly overlapping the spray and catching the turf edges. Watch the pavement as it dries. Areas that dry quicker probably had too little water applied, while areas that remain wet longer had too much. Now that your applicator is calibrated to walk 1,000 square feet per minute and your truck is calibrated to spray two gallons per minute, you?EUR??,,????'???re ready to mix your chemical ratio.

Interpreting Herbicide Labels

Turf managers buy the type of herbicide that provides the kind of turf they like, while staying within their budget. Look on the back of that container of herbicide and you?EUR??,,????'???ll see the manufacturers recommended dosage expressed in how many ounces to apply per thousand square feet. Now, that manufacturer doesn?EUR??,,????'???t care how much water you want to put in your truck tank?EUR??,,????'??+they leave it up to you to deliver the chemicals based on your personal experience. You can decide to put down one or two gallons per minute: Using more water just buys the operator more time to walk across the yard with the spray gun.

Reading the label and choosing how many gallons of water to apply per minute is simple?EUR??,,????'??+but calculating the proper ratio or chemical to water mix can be tricky.

The herbicide label says apply two ounces of product per 1,000 square feet. Assume you have a truck with a 500-gallon tank. How many square feet would the tank cover in this example if the pump delivers two gallons of spray per 1,000 square feet? The tank will cover 250,000 square feet (500 gallons divided by two gallons per square foot equals 250 gallons per square foot. Multiply 250 by 1,000 square feet and you get a 250,000-square-foot area that your 500-gallon tank will cover). Because the herbicide label requires two ounces of product per 1,000 square feet, you?EUR??,,????'???ll need to figure out just how many 1,000 square-foot areas exist within your larger 250,000-square-foot area. The answer is 250 (250,000 divided by 1,000).

Reviewing our product label, we remember that we need two ounces of product per 1,000 square-foot area. Since you have 250 of those 1,000 square-foot areas, you will need to mix 500 ounces of product (multiply 250 by two ounces) with your 500 gallons of water. In case you think you?EUR??,,????'???ll get tired measuring all 500 ounces by hand, just divide those 500 ounces by 128 ounces per gallon, and you?EUR??,,????'???ll come up with about four gallons of herbicide as the proper mix for 500 gallons of water.

Double Checking Calibration

Management should make periodical checks to see that the ?EUR??,,????'??sprayer/walker?EUR??,,????'?? stays calibrated. Consider the following suggestions: Confirm the number of lawns treated by the technician on a given day; determine the amount of spray mix used by the technician on that day and compare actual versus calculated use rates. Any discrepancies noted may mean that the pump needs to be reset or the technician needs to adjust their walking speed.

Answer: You should mix 268 ounces or 2.09 gallons with your 200-gallon tank and it will cover 67,000 square feet.

(Divide 200 gallons by three gallons of water per thousand equals 67 units of 1,000 square-foot blocks of grass, which is equal to 67,000 square feet of total area. Take 67 units and multiply by four ounces of chemical and you get 268 total ounces of herbicide needed. 268 ounces divided by 128 ounces per gallon equals 2.09 gallons.)

Agricultural programs associated with land-grant universities offer inexpensive soil tests that show what nutrients your lawn needs. To find your extension program, go to www.reeusda.gov (the Cooperative State Research, Education and Extension Service) and click on ?EUR??,,????'??state partners.?EUR??,,????'??