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How to Manage Pests

UC Pest Management Guidelines

| More pests | More crops | About guidelines |

Red thread damage to turf foliage.

Turfgrass

Red Thread

Pathogen: Laetisaria fuciformis

(Reviewed 9/09, updated 9/09)

In this Guideline:

DESCRIPTION OF THE DISEASE

Red thread may kill turfgrass in patches that are 2 to 8 inches in diameter, or the disease may occur over large areas without killing the plants. A pink web of fungal threads binds the leaves together. Look for pink, gelatinous fungal crusts projecting from the leaves to help identify this disease.

SUSCEPTIBLE TURFGRASSES

Bentgrasses, bluegrasses, fescues, ryegrasses, and bermudagrasses are susceptible to red thread.

CONDITIONS FAVORING DISEASE

This disease occurs most frequently along the coast of northern and central California but may be found in southern California on rare occasions. The disease is common under conditions of mild air temperatures (60° to 75°F) and extended periods of leaf wetness. It often appears on plants deficient in nitrogen during periods of cool or warm temperatures if there is adequate moisture (excess irrigation or rainfall).

MANAGEMENT

Providing proper irrigation and fertilization can reduce the incidence of red thread. Adequate nitrogen can usually prevent this disease from occurring. Prevent drought stress by irrigating turfgrass based on evapotranspiration needs of the turfgrass. Provide adequate air circulation and reduce shading. Fungicides are rarely warranted except in severe cases.

Common name Example trade names Ag Use
R.E.I.+		 NonAg Use
R.E.I.+
(trade name)   (hours) (hours)
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. FENARIMOL Rubigan  
  MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) 12 until dry
 
D. FLUTOLANIL Prostar  
  MODE OF ACTION GROUP NAME (NUMBER1): Carboxamide (7) 12 until dry
 
E. IPRODIONE Chipco 26019  
  MODE OF ACTION GROUP NAME (NUMBER1): Dicarboximide (2) see label until dry
 
F. 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.
 
G. MYCLOBUTANIL Eagle  
  MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) 24 until dry
 
H. PROPICONAZOLE Banner Maxx  
  MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) 24 until dry
 
I. THIOPHANATE-METHYL Fungo 50, T-Methyl E-Pro  
  MODE OF ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1) 12 until dry
 
J. TRIADIMEFON Bayleton  
  MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) 12 until dry
 
K. TRIFLOXYSTROBIN Compass  
  MODE OF ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) 12 until dry
 
L. VINCLOZOLIN Curalan, Touche  
  MODE OF ACTION GROUP NAME (NUMBER1): Dicarboximide (2) 5 days 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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Statewide IPM Program, Agriculture and Natural Resources, University of California
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