Which of the following is NOT a clue to identifying turfgrass diseases?

The identification of turfgrass diseases relies heavily on various clues that can indicate the type of problem present. Among the options listed, the type of fertilizers used does not serve as a direct clue for identifying turfgrass diseases. While fertilizers can impact the health and growth of turfgrass, they do not provide specific insights into the symptoms or signs associated with diseases, which are critical for diagnosis.

On the other hand, symptoms or signs of the problem, the species of turfgrass affected, and prevailing weather and site conditions are all vital in diagnosing turfgrass diseases. Symptoms and signs provide visible evidence of a disease's presence, while knowing the turfgrass species helps in understanding the disease's potential impact and susceptibility. Weather and site conditions can further aid in diagnosis because certain diseases thrive under specific environmental conditions, making them key factors in identifying issues in turfgrass health.