Lawns in our area typically consist of several types of turfgrass. One of those is rough bluegrass. It forms patches of a light green, dense turf in the spring and fall when there is enough moisture. It is best adapted to wet shaded conditions and may be included in seed mixtures for that environment, but can also be a contaminate in cheaper seed. Unfortunately, it often grows out into full sun areas. It is very intolerant of heat and drought and turns brown in hot, dry summers. This is what we are seeing now due to the extend period of 90°+temperatures . It is not dead, but dormant and will recover quickly when it cools down and there is more moisture. When pulled and examined you will notice the top portion will be browned (dormant), though as you move down the stolon, green plant tissue still remains. This is pictured in the photo below.

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