At this time of year, you may notice home lawns that are mostly green but have large patches of a tan-colored grass (see photo). Cool-season turfgrass species are what you will find growing in most Indiana lawns. Some examples of cool-season turfgrasses are Kentucky Bluegrass, perennial ryegrass, turf-type tall fescue, and creeping red fescue. These turfgrass species stay green most of the season depending on which part of state they are grown. Sometimes through intentional actions on the part of the homeowner or through accidental contamination, other turfgrass species can invade home lawns. Some of these grasses are warm-season turf species. Warm-season grasses stay green June through October and then turn dormant (tan color) through late fall, winter, and into early spring. In southern Indiana, these species perform well but in the upper two-thirds of Indiana they are considered a weed in most turf areas. The photo shows a lawn with a mixture of cool-season turfgrasses and a dormant warm-season turfgrass (most likely zoysiagrass). How do you correct this? The first step to determine the best course of action is always to identify the unwanted grass/plant. Once identified, as a perennial grassy weed, homeowners can attempt to control unwanted grasses with an application of a herbicide containing glyphosate (or dig out bunch-type grasses) and re-seed or re-sod the area. However, this becomes impractical for most home lawn situations. Likewise, perennial spreading turf species are difficult to control. So, in most cases, it is better just to live with the differences in turf species. For more information about this and related topics, please see the publications listed below or visit www.turf.purdue.edu .