Grass provides an attractive groundcover in many landscape situations, as well as forage for livestock and erosion control along highways and waterways. Unfortunately, many types of grass suffer from various types of diseases and adverse conditions, such as fungal disorders.
Damp conditions and inadequate drainage in the soil increase the likelihood of grass fungus by creating the conditions necessary for the growth of this type of lawn disorder. Different types of grass fungus display varied symptoms in affected lawns.
Leaf spot causes the appearance of numerous purple spots on the blades of affected grass. These spots contain lighter centers and darker perimeters. As this disease progresses, leaf tips shrivel and die. Left to spread, leaf spot disease creates large areas of dead grass. Caused by the Bipolaris sorokiniana fungus, this condition frequently attacks areas of lawns containing bluegrass. This type of fungus usually occurs during periods of warm weather. Excessive amounts of nitrogen fertilizer increase the risk of leaf spot in lawns.
Necrotic Ring Spot
This serious disease commonly affects well-maintained lawns in the spring and fall. Symptoms appear as discolored patches among healthy areas of grass. Measuring between 6 and 24 inches, these patches contain red and straw-colored blades around the outer circumference of the rings. Close inspection of the diseased roots and crows reveals the appearance of black strands. Often caused by soil compaction and incorrect watering practices, this type of fungus quickly spreads and causes extensive damage.
Yellow patch frequently appears in new sod. Early in its development, this fungus creates small patches of light green and yellow grass. These patches measure between 2 and 3 inches in the beginning, quickly spreading in size to reach almost 2 feet wide. Often, the soil beneath the patches appears lower than the remaining soil. Grass containing yellow patch fungus develops tan spots along the upper segments of individual blades. The outside section of these patches turns slightly reddish. Laying new sod over heavy soil increases the likelihood of this type of grass fungus.