October is a good time to kill Tall Fescue. I like killing Tall Fescue because it is perhaps the most invasive non-native plant in North America. In my opinion it is more invasive than Purple loosestrife and Phragmites, yet why don’t we hear more about it? Not only is Tall Fescue invasive, but it is also toxic!Our lawn, like most of the lawns around this neighborhood, is mostly Tall Fescue, a variety commonly called Kentucky 31, for where it originated. It's a popular lawn grass because it is drought resistant, rugged, and resistant to pests. It is a cool season grass, which means it grows best in spring and fall, struggling in our summer heat.
We used a glyphosate product last week to start killing a pasture that is predominately Tall Fescue. We are doing this in preparation to replace the Tall Fescue with native warm season grasses next spring. When the new grasses get established, we will use them for pasture during the hot summer months of July and August when the rest of our cool season grass pastures on the farm usually go dormant.
Research shows that killing Fescue in the fall results in only 20 percent of it coming back; whereas if you kill it in the spring, 60 percent of it will come back. We plan to spray again next spring just prior to planting the native grasses.
I also spray around the trees we planted several years ago because the Fescue is allelopathic to newly planted trees. That means the Fescue gives off a toxin that inhibits the growth of new seedlings. If you want to plant trees into a Fescue sod, you should kill the Fescue first.
Because of Fescue’s growth habit, it harbors mice and voles. Mice and voles eat tree seedlings. Mice and voles also attract hawks. Hawks kill quail. Introducing Fescue into our natural system here didn't work out very well.
It is, in fact, slightly toxic, due to a fungal symbiont, which gives the grass it's drought resistance, and helps protect it from some herbivores. Despite this, it is often used it pastures. The effect of the toxins are generally minor, slowed growth, but can be fatal for mares and foals who graze on it exclusively. Not generally a problem in my yard. The deer are welcome to chew it down before I have to mow it.
I wouldn't be opposed to getting rid of it, or of getting rid of the lawn entirely, but that could only come in small steps, as it would be a lot of work to replace the lawn area with other landscaping. I don't think Georgia would just settle for a weed bed.