If you have coarse, light green clumps standing above the rest of your lawn, this is almost certainly what you are looking at. The name has confused homeowners for eighty years, and nobody selling the stuff has been in a hurry to clear it up.
Telling the two apart
Kentucky 31, which is what is in a lot of older lawns around here:
Turf type tall fescue, which is what we seed:
Where the name came from
In 1931 a University of Kentucky agronomist named E. N. Fergus was in Menifee County to judge a sorghum syrup show. He stopped at a hillside farm owned by W. M. Suiter and found a stand of grass that had been holding green through a bad drought, untended, for more than forty years. He took a few pounds of seed back with him.
It went into test plots the next year and was released in 1943 as Kentucky 31. The 31 is the year he found it. The Kentucky is the state. Neither one has anything to do with Kentucky bluegrass, which is a different species entirely.
It was released as a forage grass. It was so much a cattle grass that its most famous problem is a condition it caused in the cattle grazing it. Nobody was thinking about lawns.
Same species, bred in the opposite direction
Here is the part that trips people up. Kentucky 31 and the turf type tall fescue we seed are the same species. Breeders spent decades selecting the other way from that original pasture grass, toward a narrower blade, a darker color, and a plant that fills in instead of standing up in a clump.
That is why the variety name on a seed tag matters more than the species name. A bag that says tall fescue and nothing else can hold either one.
What can be done about it
Not much that is quick, and that is the honest answer. Because it is the same species as the good tall fescue, there is no way to take it out selectively and leave the rest of the lawn standing.
That leaves two practical paths. Kill the worst patches, tear them out, and reseed those areas. Or overseed with turf type varieties over several fall seasons and let the good grass gradually outnumber the clumps. The first is faster and looks worse for a few weeks. The second is slower and nobody notices it happening.
Which one makes sense depends on how much of the lawn is affected. That is worth walking together rather than guessing from a photo.
If the clumps bother you
We seed turf type tall fescue in the fall, when new seedlings get autumn, winter, and a full spring to root before their first real heat. Give us a call and we will look at what is actually growing out there before anyone spends money on seed.