Applying pesticides and fertilizers at the proper rates are essential to achieve satisfactory weed, insect, and disease control. Too little chemical results in poor pest control and reduced yields, while too much chemical injures the crop, wastes money, and may increase the risk of surface and ground water pollution. Directions on pesticide container labels specify the application rates that produce the best results. However, proper application rates can be attained only if sprayers work well, used properly and calibrated correctly.