What Diseases are Prevalent Under Shade Conditions?Most grass species need a minimum of four hours of sunlight to remain healthy. If grasses do not have enough sunlight to remain healthy, they can become weak and susceptible to disease and other stresses. Some grass species, such as the fine fescues and tall fescues, persist better in a shady environment than other species. Others, such as Kentucky bluegrasses or perennial ryegrasses, require more sun to remain healthy. Once grasses become weakened, diseases may more easily attack grasses ill-suited to these shady environments. Grass mixtures such as The Rebels® Brand Shade Mix for Tall Fescue Lawns are recommended for partial shade or shady environments so that each grass species which is best suited to a particular site predominates.
One disease that occurs in a shady environment is powdery mildew. Powdery mildew (Erysiphe graminis) is a foliar disease that forms a whitish powder on the leaf blades and can appear unsightly. Although unsightly, it is not considered a serious or harmful grass disease. Chemical control is generally not recommended since the growth is superficial. Although diseases such as dollar spot, brown, leaf spot and summer patch can be damaging in sun or shade, undue stress placed on the grass by its not being grown in an appropriate location may weaken the turf and make it more susceptible to these diseases.