All turfgrasses can be infected with rust fungi, but Kentucky
bluegrass, perennial ryegrass, tall fescue and zoysiagrass tend
to be most susceptible. Early symptoms of rust diseases include
light yellow flecks on leaves and stems, giving the lawn a
yellow cast. The leaf tissue ruptures at these yellow spots, and
spores of the fungus are produced. The pustules may be yellow,
orange, brown or red. The spores rub off very easily on hands,
shoes, clothing and animals. Often, the disease goes unnoticed
until you mow the lawn and see that your white shoes are covered
with a dusty coating of rust-colored spores.
turf appears thin and tinted yellow, red or brown, depending on
the fungus and time of year. The turf becomes weakened,
unsightly and more susceptible to injury from environmental
stress and other disease pathogens. Grasses growing slowly under
stressful environmental conditions (such as big swings in
temperature and moisture) are most susceptible to rust,
particularly when water, fertility and soil compaction are
inadequate for good growth. There are also varieties with
resistance and susceptibility to rust.
Management measures should target stress areas.
Leaf wetness is required for infection, so it is important to
water early in the day so the turf can dry before night. Water
turf infrequently, but to a depth of 6 inches or more at each
watering. Avoid frequent, light sprinklings.
Fertilize to keep the grass growing about 1 inch per week in
summer and early fall droughts. Use balanced fertilizer and do
not apply excessive nitrogen.
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As the grass grows, it pushes rust-infected leaves outward, making
it easy to mow and remove infected blades. It may be helpful to
catch these clippings and remove them from the area. Mow regularly
to remove infected leaf tips, but avoid mowing below the recommended
height for the particular turf species.
Prune surrounding trees and shrubs to improve light penetration
and air circulation around densely shaded areas.
If the lawn is badly infected or the combination of rust and
other stress produces a poor lawn and forces a renovation, it is
ideally done in late August or early September. Use a blend of turf
cultivars with resistance to rust, but beware that what was once
resistant may no longer be. The rust fungi keep evolving and
eventually defeat the old-line resistance.
Preventive fungicides are available, but they offer only a
temporary solution. The fungicide treatments tend to be costly and
time-consuming. Daconil is the most common fungicide used on turf,
but following the management practices will produce better long-term
To offer a ray of hope, diseases must have ideal conditions to
develop. Just wait for a major weather change and the rust will go
away. At least for a while.
University of Illinois Extension, Logan County]