Which disease is caused by fungi and is characterized by blemishes on turfgrass leaves?

The disease caused by fungi and characterized by blemishes on turfgrass leaves is leafspot. Leafspot diseases are often identified by the presence of small, circular, and discolored areas on the leaves of the grass. These spots can vary in color, typically appearing as brown or dark tan lesions, and may be surrounded by a yellow halo. The fungi responsible for leafspot thrive in warm, humid conditions, making the disease more prominent during certain weather patterns.

In contrast, other diseases listed, while also caused by fungi, manifest differently. Root rot primarily affects the root system rather than the leaf blades and is characterized by a decay of the roots, leading to overall plant decline. Powdery mildew, on the other hand, is recognized by a white, powdery fungal growth on the surface of leaves rather than distinct blemishes. Brown patch is a more severe disease associated with large, brown areas or patches on the turf, often affecting the entire leaf blade rather than just creating spots. Thus, leafspot stands out as the option that accurately fits the description of causing blemishes specifically on turfgrass leaves.