Which factor contributes to the development of gray leaf spot?

The development of gray leaf spot is primarily associated with damp conditions, making this the correct choice. This fungal disease thrives in environments where moisture is prevalent, as it encourages the growth and spread of the pathogen. Prolonged leaf wetness, often caused by high humidity or frequent rainfall, creates an ideal setting for the fungus responsible for gray leaf spot to reproduce and infect the host plants.

While high temperatures can also play a role in disease development, they are not as critical as the moisture factor. Excessive mowing may affect the overall health of the plant but does not directly contribute to the conditions that promote the disease. Low humidity, on the other hand, generally reduces moisture levels and does not support the conditions needed for gray leaf spot to flourish. Thus, it is the combination of warm temperatures and damp conditions that primarily facilitates the spread of this particular fungal disease, with the latter being the key factor.