The Purdue Plant and Pest Diagnostic Laboratory

What's Hot at the P&PDL on
September 4, 2004

 

Rusty Turf

Gail Ruhl, Senior Plant Disease Diagnostician, Interim P&PDL Director, Botany & Plant Pathology

We have received a number of questions in regard to what is causing the orange color on grass blades as well as on white tennis shoes that have been worn out in the yard. The orange color is from numerous spores produced in pustules on the surface of grass blades infected by the rust fungus (Puccinia spp.). This 'colorful' disease is currently noticeable on perennial ryegrass and common Kentucky bluegrass in home lawns throughout Indiana. The spores stick to shoes, dog feet, and any other item contacting the infected turf.

Rust is favored by warm summer days with cool nights, and heavy morning dew, or frequent rain showers that keep grass wet. In addition, turf with a reduced growth rate is more heavily affected. Reduced growth may be due to a lack of nitrogen, soil compaction, or any other growth-limiting factor.

The damage from this disease is mostly aesthetic, and is not likely to kill the turf since rust on turfgrass only affects the blades, and not the crown of the plant. Thus, fungicidal applications are generally not recommended for home lawns. Infected turfgrass typically grows out of the disease once environmental conditions favor rapid turf growth. Good fall turfgrass cultural practices, such as proper fertilization to promote blade growth and core aeration to alleviate compaction, should support the recovery of a lawn.

A more long-term solution is to avoid the disease altogether by using resistant cultivars of turfgrass. There is a range of susceptibility of perennial ryegrass cultivars in the National Turfgrass Evaluation Program (NTEP) plots at the Ohio State University Turfgrass Research Center. Some cultivars are virtually free of infection, while others are being hammered! NTEP evaluation results are available online at the following web site: http://www.ntep.org/

You may refer to http://www.agcom.purdue.edu/AgCom/Pubs/BP/BP-110-W.pdf for more information on Rust on Turf.

Figures 1 and 2 courtesy of Purdue Turf Program

Figures 3 and 4 courtesy of Jonathan Ferris, Henry County Extension Office


The information given herein is supplied with the understanding that no discrimination is intended and no endorsement by the Purdue University Cooperative Extension Service is implied. Any person using products listed assumes full responsibility for their use in accordance with current direction of the manufacturer. Purdue University is an equal opportunity/equal access institution.

Information listed is valid only for the state of Indiana.

 

Click on the small image to view a larger image.

Figure 1. Rust on turf

Figure 2. Rust on shoes

Figure 3. Overall view of rust-infected turf

Figure 4. Close-up of rust pustules on leaves

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service