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UC Pest Management Guidelines


Rust damage to bluegrass foliage.

Turfgrass

Rust

Pathogens: Puccinia striiformis, P. graminis, P. coronata, and Uromyces spp.

(Reviewed 9/09, updated 9/09)

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.

SUSCEPTIBLE TURFGRASSES

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.

MANAGEMENT

Rust can usually be managed with proper mowing, fertilizing, and irrigation practices.

Cultural Control
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.

Treatment Decisions
Rust can usually be managed successfully through cultural practices, but in severe cases fungicide applications can be made.

Common name Example trade names Ag Use
R.E.I.+
NonAg Use
R.E.I.+
(trade name)   (hours) (hours)

  Calculate impact of pesticide on air quality
When choosing a fungicide, consider general properties as well as information relating to environmental impact.
 
A. AZOXYSTROBIN Heritage  
  MODE OF ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) 4 until dry
 
B. CHLOROTHALONIL Daconil  
  MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M5) 12 until dry
 
C. MANCOZEB Fore, Dithane M-45  
  MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M3) 24 until dry
  COMMENTS: Dithane M-45 registered for use on sod farms only.
 
D. MYCLOBUTANIL Eagle  
  MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) 24 until dry
   
E. PROPICONAZOLE Banner Maxx  
  MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) 24 until dry
 
F. THIOPHANATE-METHYL Fungo 50, T-Methyl E-Pro  
  MODE OF ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1) 12 until dry
 
G. TRIADIMEFON Bayleton  
  MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) 12 until dry
 
H. TRIFLOXYSTROBIN Compass  
  MODE OF ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) 12 until dry
 
1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://www.frac.info/). Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode of action Group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode of action Group number; for fungicides with other Group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode of action Group number.
+ Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Agricultural use applies to sod farms and commercial seed production.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Turfgrass
UC ANR Publication 3365-T
Diseases
F. Wong, Plant Pathology, UC Riverside
M. A. Harivandi, UC Cooperative Extension, Alameda County
Acknowledgment for contributions to Diseases:
J. Hartin, UC Cooperative Extension, San Bernardino County
M. E. Grebus, Plant Pathology, UC Riverside

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