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Application of the correct amount of fertilizer and pesticide to a lawn is important! Too much fertilizer may burn the grass. Too little herbicide gives ineffective weed control.
There are many brands of lawn spreaders. Each spreader has its own method for setting the rate of application. To confuse matters even more, a spreader setting that accurately dispenses the correct fertilizer rate at one setting might not dispense the same amount of pesticide or seed at that setting.
Hand-held and backpack sprayers are extremely useful for treating small turf areas infested with weeds. But they have to be calibrated to apply the recommended rate of a herbicide.
Most herbicides used in turf grasses control weeds without injuring the turf. But that depends on the rate applied. The rate is usually on the product label as the amount to be applied to 1 acre or 1,000 square feet.
For example, the highest recommended rate of Trimec Classic for Bermuda grass and tall fescue is 1.5 fluid ounces per 1,000 square feet.