Rusty Old Turf
Rust is a common disease of cool season lawns during the fall. The disease is most severe on Kentucky bluegrass, perennial ryegrass, and tall fescue especially when growth has slowed. Although often associated with cool season turf, rust can occur on warm season turfgrasses too.
Photograph 1. Rust symptoms on a homelawn.
Environmental conditions favorable for rust include temperatures in the range of 68 to 86°F (20 to 30° C), situations of low light, and wetness on the leaf. Symptoms appear as a yellowish to reddish colored turf. Upon closer examination of the leaves, the reddish-brown pustules are the sign for this disease. These pustules are the result of another common sign of this disease, which often gives rise to a number of phone complaints or questions, orange shoes. The orange color is a result of the spores from the pustules being deposited on shoes as a person walks through the lawn.
Photograph 2. Rust leaf symptoms are similar and often confused with leaf spot.
The major pathogens of rust are in the genus Puccinia. The species of Puccinia are often specific to the turfgrass species. Regarding cool season turfgrasses, primarily the bluegrasses and ryegrasses, the major rust diseases are known as stem, stripe and leaf rusts.
Photograph 3. A major sign of the pathogen and a diagnostic key is the appearance of orangish-reddish pustules.
Turf that is growing slowly and under some stress is susceptible to rust. For example, drought, other pest stresses, or inadequate nutrient levels predispose the turf to infection. Cultural methods for reducing the severity of rust include selecting rust resistant cultivars, and water and fertilize to reduce any moisture or nutrient deficiencies.
Phtograph 4. A characteristic sign of the pathogen that causes rust is the orange spores that often coat shoes as one walks through the infected turf.
Chemically, one effective group of fungicides for controlling rust are the sterol inhibiting fungicides like Banner Maxx II and the strobulurins like Heritage.
About the author
Dr. Karl Danneberger is a professor of Turfgrass Science at The Ohio State University. Dr. Danneberger's contact information can be found here. You may also follow Dr. Danneberger on Twitter: