Dollar spot is readily distinguished, however, by characteristic lesions on the leaf blades of live plants near the border of the affected area. Lesions are light tan with a reddish-brown border, and usually radiate from the margins of the leaf blade. On fine bladed grasses such as bentgrass, the lesions usually girdle the leaf blade. If the turf is examined when the disease is active early in the day before the dew dries, cobweb-like mycelium of the fungus can be seen growing on affected areas. During early stages of the disease, affected plants may appear water-soaked and wilted, but spots quickly fade to a characteristic straw color.
Several factors influence the occurrence and severity of dollar spot.
Low soil moisture has been reported to enhance dollar spot activity, but moisture from dew, light rain or irrigation must be present on the foliage for the disease to develop. The dollar spot fungus survives unfavorable temperature and moisture conditions in plant tissue and thatch as dormant, compact masses of mycelium, called sclerotia. Low nitrogen and potassium levels in the soil have been reported to increase the severity of dollar spot. Some rather severe outbreaks of dollar spot have been brought under control by the application of soluble nitrogen fertilizer. However, the beneficial effect of nitrogen is thought to be due to rapid recovery of the grass during periods of reduced disease activity.