Brown patch appears as circular patches in the lawn that are brownish yellow in color and range from 6 inches to several feet in diameter. It effects all cool season lawn grasses but is especially harmful to ryegrass and tall fescue. Kentucky bluegrass and fine fescues can occasionally be effected but damage is usually minimal in these species. Brown patch also affects a variety of warm season grasses including St. Augustinegrass and Zoysiagrass. Brown patch is most likely to occur during extended periods of heat and humidity when night-time temperatures remain above 68° F
Powdery mildew is a fungal disease common to many plants each with it’s own species of the disease. Powdery mildew on lawns is most common on cool season grasses, Kentucky bluegrass specifically. Powdery mildew can appear quickly on a lawn, mainly in shady areas and more frequently during cloudy or overcast periods. The presence of powdery mildew is evident by a white dust appearance on the leaf blades.
Red Thread. The presence of red or pink webbing or thread is the tell tale sign of red thread. Red thread is most likely brought on by low levels of nitrogen in the soil. Red thread is a relatively harmless disease that can be used as a good indicator that it’s time to fertilize the lawn. Cool season grasses like red fescue, ryegrass, Kentucky bluegrass, and bentgrass are most susceptible
Snow mold is a fungal disease that appears in the early spring as the snow melts. There are two types of snow mold. Grey snow mold (also known as Typhula blight) and pink snow mold (sometimes referred to as Fusarium patch). Pink snow mold infects the crown of the plant and can cause more severe injury than gray snow mold which only infects the leaf tissue. Snow mold is caused when there is an extended period of snow cover on ground that is not completely frozen. Snow mold can also occur under leaves that have not been cleaned up or amongst long grass that should have been mowed once more before winter set in.
Fairy rings are naturally occurring arcs of mushrooms in grassed areas or forests. They can be incomplete or complete circles and can grow to be over 30 feet in diameter. There are three types of fairy ring found on lawns, those with a darker green flush of growth, a zone of dying grass and mushrooms, those with only a darkened green ring and mushrooms, and those with only mushrooms. Fairy rings do not cause widespread damage and are very hard to get rid of so they are most often just left alone.