How to Manage Pests
UC Pest Management Guidelines
Pathogens: Puccinia striiformis, P. graminis, P. coronata, and Uromyces spp.
(Reviewed 9/09, updated 9/09, pesticides updated 12/16)
In this Guideline:
DESCRIPTION OF THE DISEASE
Rust begins as small yellow spots on leaves and stems that form elongated, reddish brown or orange pustules. Shoes and clothes are often stained orange by the spores when walking through infested areas. Rust kills leaves and debilitates plants when it is severe. The turfgrass quality is reduced because of poor color and reduced plant vigor. Rust survives as dormant mycelia in infected plants and as teliospores; it may spread to turf from infections on other grasses and woody ornamentals.
Bluegrasses, ryegrasses, zoysiagrass, and tall fescue.
CONDITIONS FAVORING DISEASE
Moderately warm, moist weather favors rust development. Moisture in the form of dew for 10 to 12 hours is sufficient for the spores to infect plants. Warm air temperatures (70°to 75°F) and extended periods of leaf wetness favor the development of the disease. The disease is more severe in turf deficient in nitrogen.
Rust can usually be managed with proper mowing, fertilizing, and irrigation practices.
To reduce the incidence of rust, maintain turfgrass vigor by applying adequate but not excessive nitrogen fertilization and irrigate in the morning according to the evapotranspiration needs of the turfgrass. Provide good air movement on surface of grass. Mow the turfgrass regularly and remove clippings if the lawn is infected to reduce the number of spores. Mixtures of several compatible turfgrass species fare better against rust than turfgrass composed of a single species. Most Kentucky bluegrass and tall fescue varieties currently marketed in California are fairly resistant to rust.
Rust can usually be managed successfully through cultural practices, but in severe cases fungicide applications can be made.
UC IPM Pest Management Guidelines: Turfgrass
A. Downer, UC Cooperative Extension, Ventura County
Acknowledgment for contributions to Diseases:F. Wong, Plant Pathology, UC Riverside
J. Hartin, UC Cooperative Extension, San Bernardino County
M. E. Grebus, Plant Pathology, UC Riverside