University of Illinois Extension
Bruce Spangeberg

These articles are written to apply to the northeastern corner of Illinois. Problems and timing may not apply outside of this area.

Stateline Yard & Garden

Rust Again Problem on Lawns

July 29, 1999

Walk across a lawn or turf area lately and notice your shoes get an orange powder on them? Once again, it is time for rust disease on lawns. Rust is a common disease, caused by fungi, which typically appears as lawns slow down in growth in mid to late summer.

Rust appears as an orange or yellowish-orange powder (spores) on grass leaf blades, making it one of the easier lawn diseases to identify. The orange powder comes off easily. Dry weather is usually a factor, so some areas that have had significant rains in the past few weeks may not be showing as much rust as lawns in drier areas. Rust typically develops on lawns growing very slowly. Overall, lawns may assume a yellow, red, or brown appearance.

Low fertility (in particular nitrogen) and low water availability slow down grass growth, allowing rust to develop. Seasons with excess rain may have rust outbreaks due to depletion of available nitrogen. Cool nights with heavy dew and light, frequent rainfall add to the ideal conditions for rust to develop. Warm, cloudy, humid weather followed by hot, sunny weather also favors rust development on lawns.

Kentucky bluegrass, perennial ryegrass, and tall fescue are all affected, depending on cultivars. Rust spreads via air, water, shoes, equipment, and sod. Rust may weaken turfgrasses and make them more susceptible to other problems.

Control rust through sound lawn care practices. Begin by choosing a quality turfgrass seed blend of several cultivars of the species desired for the site. Resistance to rust can vary according to the race of the disease present. A diverse turf stand helps combat rust and numerous other turf problems.

Maintain lawns through sound watering, mowing, and fertilizing. When rust occurs in late summer, improved growth conditions of early fall often get lawns growing more vigorously and the rust fades away. Early September is a key time for fertilization. If conditions are dry, irrigation is also needed to increase the growth rate of the lawn.

Finally, address any contributing factors that could be making rust more severe. Manage problem thatch. Check soil phosphorus and potassium levels through soil testing. Also assure good airflow over the site and light penetration by pruning trees and shrubs in the area near the lawn.


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