Which of the following is NOT classified as a turfgrass pest?

Nutrient leachers are not classified as turfgrass pests because they refer to a phenomenon where essential nutrients are washed away from the soil, often due to excessive irrigation or rainfall. This results in nutrient deficiencies but does not involve any organism or pathogen that harms the turfgrass directly. In contrast, weeds, insects, and diseases are all categorized as turfgrass pests because they actively cause damage to the grass: weeds compete for resources; insects can feed on the grass or its roots; and diseases can lead to deterioration through various pathogens. Understanding the distinction between these categories is crucial for effective turf management, allowing for targeted control measures against actual pests rather than addressing environmental factors like nutrient leaching.