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.