How to Manage Pests

UC Pest Management Guidelines

Turfgrass

Red Thread

Pathogen: Laetisaria fuciformis

(Reviewed 9/09, updated 9/09, pesticides updated 12/16)

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 Amount to use Ag Use
REI‡
NonAg Use
PHI‡
(Example trade name)   (hours) (days)

UPDATED: 12/16
Calculate impact of pesticide on air quality
Bee precaution pesticide ratings
When choosing a pesticide, consider its usefulness in an IPM program by reviewing the pesticide's properties, efficacy, application timing, and information relating to resistance management, honey bees (PDF), and environmental impact. Not all registered pesticides are listed. Always read the label of the product being used.
 
A. AZOXYSTROBIN
  (Heritage) 0.2–0.4 oz/1000 sq ft 4 Until dry
  MODE-OF-ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11)
 
B. CHLOROTHALONIL
  (Daconil Action) Label rates 12 Until dry
  MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M5)
 
C. FLUTOLANIL
  (Prostar WG) Label rates 12 Until dry
  MODE-OF-ACTION GROUP NAME (NUMBER1): Carboxamide (7)
 
D. IPRODIONE
  (Chipco 26019) 4 fl oz/1000 sq ft. See label Until dry
  MODE-OF-ACTION GROUP NAME (NUMBER1): Dicarboximide (2)
 
E. MANCOZEB
  (Fore 80WP, Dithane M-45) 4–8 oz/1000 sq ft 24 Until dry
  MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M3)
  COMMENTS: Dithane M-45 registered for use on sod farms only.
 
F. MYCLOBUTANIL
  (Eagle 20EW) 1.2 fl oz/1000 sq ft 24 Until dry
  MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3)
 
G. PROPICONAZOLE
  (Banner Maxx) 2 fl oz/1000 sq ft 12 Until dry
  MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3)
 
H. THIOPHANATE-METHYL
  (Fungo Flo) Label rates 12 Until dry
  MODE-OF-ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1)
 
I. TRIADIMEFON
  (Bayleton 50 Turf and Ornamental) Label rates 12 Until dry
  MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3)
 
J. TRIFLOXYSTROBIN
  (Compass) Label rates 12 Until dry
  MODE-OF-ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11)
 
K. VINCLOZOLIN
  (Curalan EG, Touche EG 2.7 lb/acre (1 oz/1000 sq ft) 120 (5 days) Until dry
  MODE-OF-ACTION GROUP NAME (NUMBER1): Dicarboximide (2)
 
1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://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 (REI) 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

A. Downer, UC Cooperative Extension, Ventura County
M. A. Harivandi, UC Cooperative Extension, Alameda 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

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