How does the severity of dollar spot change with nitrogen levels in the soil?

The relationship between nitrogen levels in the soil and the severity of dollar spot is critical to understand for effective management of this turf disease. Dollar spot, caused by the fungus Sclerotinia homoeocarpa, tends to thrive in conditions where there is low nitrogen availability. When nitrogen levels are low, the growth of grass is inhibited, making it more susceptible to diseases like dollar spot.

Low nitrogen levels lead to weaker, less vigorous grass that cannot effectively compete with pathogens. Additionally, when nitrogen is scarce, the plant's ability to recover from stress and disease damage diminishes, allowing dollar spot to develop more easily and aggressively.

In contrast, adequate nitrogen levels promote stronger and healthier turfgrass that can better resist infectious diseases. A well-fertilized lawn has more robust growth, which helps in both recovery from potential infection and in maintaining overall plant health.

Therefore, understanding the role of nitrogen in disease severity is crucial for effective turf management, highlighting why low nitrogen levels increase the severity of dollar spot.