Which of the following is an example of a grievous turfgrass disease?

The correct answer, leafspot, is identified as a grievous turfgrass disease due to its ability to significantly damage and weaken turfgrass, leading to severe aesthetic and functional issues on lawns and athletic fields. Leafspot infections often manifest as irregularly shaped brown patches on the grass blades, which can lead to widespread turf decline if left unaddressed. The economic impact on maintenance costs and aesthetic value is substantial when dealing with this type of disease.

While other diseases listed can also affect turfgrass, they may not have the same level of severity or damage as leafspot. Fusarium wilt and anthracnose are indeed harmful, but they primarily affect specific turfgrass types under particular conditions. Powdery mildew, while it can be disruptive, typically does not lead to the same level of turf decay as leafspot does. Therefore, leafspot is highlighted for its grievous impact on turfgrass health and maintenance, making it a significant concern in turf management.