Identification of Rust Disease
Rust disease in lawns appears as an orange or yellowish-orange powder (spores) on grass leaf blades. It especially shows up in late summer to early fall when the weather is dry. Rust typically develops on lawns and other turf areas that are growing very slowly. Overall, the turf may assume a yellow, red, or brown appearance. Close examination reveals the pustules, which easily rub off on your hand. Rust spores can easily be tracked into homes. Orangish rust spores are visible on leaf blades of a grass plant.
Causes of Rust Disease
- Low fertility (in particular nitrogen) and low water availability slow down turf 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.
- Kentucky bluegrass, perennial ryegrass, and tall fescue are all affected, depending on cultivars.
- Rust spreads via air, water, shoes, equipment, and vegetative turf material (sod). Rust may weaken turfgrasses and make them more susceptible to other problems.
Control of Rust
Per Bruce Spangenberg, Former Extension Editor, Horticulture, University of Illinois Extension, “Fungicides are rarely suggested on home lawns for rust control. Focus on cultural practices…”
Control rust disease through sound turf management / cultural 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.
- Water early in the day so the grass dries quickly.
- Manage problem thatch by letting us core aerate your lawn every fall.
- Increase vigor with an early fall nitrogen application, but don’t overdo it.
- 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.
- Most of all, be sure to maintain your lawn through sound watering, mowing, and fertilizing habits.
When rust disease 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 grass.
Sources for Rust Information
http://urbanext.illinois.edu/turf/rustlawn.cfm 7/30/2014 “Rust Turns Lawns Orange” Bruce Spangenberg.
https://ipm.illinois.edu/landturf/diseases/turfgrass_rust/index.html 8/8/2014 “Rusts of Turfgrasses”. June 2000.