Rust, in most instances, is considered as only a minor annoyance. Even though grass blades are flecked with orange and slightly discolored, there is little concern, for the disease generally disappears with a change in the weather, or fertilization. Many times this is true, but a neglected rust problem that lingers for days can often result in the loss of good turf. Rust seldom becomes a problem until the grass stops vigorous, active summer growth. This generally occurs after an extended dry period.

Brown patch will affect all grass types in temperate climates. The disease is favored by excess thatch, high temperatures (75° - 95° F), high humidity (99 - 100%), excess moisture, and lush growth caused by excess nitrogen. Closely mowed turf and particularly the bentgrasses of golf courses are especially susceptible and easily damaged by brown patch. In addition, it can be extremely destructive to St. Augustine grass from fall to early spring. Moisture on the grass blade is essential to the spread of brown patch.

Snow Molds are patches up to 12 inches across that start to appear in early spring as snow begins to melt. One kind is Typhula Blight which consists of gray-colored dead patches with tiny tan to black spherical fungal sclerotia. This disease develops only under snow cover, especially when soil is unfrozen. The other kind is Fusarium Patch which consists of pink-tinged or pink-bordered patches that fade to tan as they dry. There are no fungal sclerotia, and this disease occurs with or without snow cover.

Red Thread kills grass in patches that are 2 to 8 inches in diameter. The disease may occur over large areas without killing the plants. A pink web of fungal threads binds the leaves together. Look for pink, gelatinous fungal crusts projecting from the leaves to help identify this disease.