There are many varieties of fescue that can be found growing wild throughout North America. When not purposely cultivated, it is often a nuisance. This cool-season grass actively grows when most other plants are dormant and it can quickly take over a yard or garden. Furthermore, fescue often carries fungi that can be passed on to your lawn or garden plants. Fescue is notoriously difficult to get rid of, and hand-weeding rarely works. Often, the only way to kill fescue for good is to use a glyphosate-based broad-spectrum herbicide.
Cut or mow the fescue as close to the ground as possible. Allow it to grow 6 inches high before treating it.
Apply the herbicide according to the manufacturer's instructions. Spray herbicides should be applied on windless days when there is no rain forecast for at least 48 hours.
Wait at least 1 week before re-seeding or planting in the area where you applied the herbicide. It will take at least that long for the herbicide to wash out of the soil.
Keep an eye on the treated area. If the fescue starts to come back, wait until the grass is 6 inches high to re-treat it. Otherwise it may develop an immunity to the herbicide.
Do not till or mow the area until you have successfully killed the fescue and it has not grown back for at least one month.