Are you part of the 66 percent to 77 percent of growers who spray more or less pesticide needed, leading to either money wasted down the nozzle or crop losses? If you don’t know, there's one thing you can do about it, and now is the time to do it: Calibrate your sprayer.

Erdal Ozkan, an Ohio State University Extension agricultural engineer, says there's no better time than early spring for growers to take a look at their sprayers and find out if they are delivering the proper gallons-per-acre application rate.

"If you don't calibrate your sprayer frequently, it's as if you were driving your car with a speedometer that doesn't work," said Ozkan, who is also a professor in the Department of Food, Agricultural and Biological Engineering and a researcher with the Ohio Agricultural Research and Development Center. "You assume you know what speed you are traveling at from habit, but you are not really sure. The problem with a sprayer is that nozzles wear out with use, application rates change with different field conditions, and traveling speeds also change. Many growers don't take these factors into account."

Data from Ohio and other states indicates that only one out of every three to four applicators applies chemicals at rates that are within 5 percent (plus or minus) of the intended rates. Application rates within plus or minus 5 percent represent the accuracy level recommended by the U.S. Department of Agriculture and the U.S. Environmental Protection Agency.

Surveys also indicate that 67 percent of applicators who calibrated their equipment before every spray application had application errors below 5 percent, Ozkan said. Conversely, only 5 percent of applicators who calibrated their equipment less than once a year achieved the same degree of accuracy.

Ozkan said growers should calibrate their sprayers in early spring and every time operating conditions (different ground surfaces, for example) change or a different type of chemical is to be used.

"Frequent calibration is even more important with liquid applications because nozzles wear out with use, increasing the flow rate and leading to overuse of chemicals, which impacts growers' budgets and can lead to crop damage and contamination of groundwater and the environment," Ozkan explained.