Experts and BHG readers answer.
Purple nutsedge, sometimes called nut grass, occurs in lawn turf because the soil is not properly nutritious, or is compacted, and the lawn grass is stressed. Fish Agra helps to improve the soil and give you a healthier lawn. Although it is compatible with Round Up and other herbicides, Round Up kills anything it touches, so applying it with an eyedropper might be the safest way to get rid of the nut grass in the short term, rather than mixing it in with the Fish Agra. For long term control of this weed, improve the soil.