Pacific Northwest 1998 An Online Guide to Plant Disease Control

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OSU Extension Office
 
Lawn and Turf -- Red Thread
 
Cause: The disease formerly was known as Corticium red thread and is caused by the fungus Laetisaria fuciformis. Commonly seen in Oregon and Washington, it is primarily cosmetic and rarely kills any grass. Fungi live on diseased grass and in soil. Disease occurs in wet humid weather in late fall, winter, and early spring, especially in fine fescue lawns. It is more severe on perennial ryegrass, red and Chewing fescue, and bentgrass. Hard fescue is resistant. Red thread is more severe on lawns low in vigor.
Symptoms: Circular, irregular yellow patches, 2 to 24 inches, become brown and dead-looking. Affected aerial parts are bound together with a faintly pinkish web. Small, pink, hornlike fruiting bodies of fungus on leaf blades are a sure indication of red thread.

Red threads are fungal mycelium.

Occurs on poorly fertilized lawns.

 
Cultural control: This disease can be controlled with cultural practices alone.

  1. Fertilize with adequate nitrogen in a balanced nutritional program.
  2. Prevent drought stress by using an adequate amount of water based on local growing conditions.
Chemical control: Not recommended for home lawns. Focus on cultural control methods. Tolerant strains of many fungal pathogens can be troublesome when one product is are used exclusively in a spray schedule. To reduce the possibility of fungicide tolerance, alternate or tank-mix with fungicides having different modes of action. See the table Fungicide Families later in this book. Note: Avoid using fungicides containing benomyl or thiophanate-methyl (such as AllBan, Halt and Cleary's 3336) on aff ected lawns; they can increase the severity of the disease.

  1. 26 GT Fungicide at 4 fl oz/1,000 sq ft. 24-hr reentry.
  2. Bayleton 50 T&O at 0.5 oz/1,000 sq ft (preventive) to 1 oz/1,000 sq ft (curative). Landscape only, not for use on plants for sale. 12-hr reentry.
  3. Compass O 50 WDG at 0.1 to 0.25 oz/1000 sq ft. Do not use organosilicate additives or more than 2 sequential applications. 12-hr reentry.
  4. Curalan EG at 1 oz/1,000 sq ft after mowing. 12-hr reentry.
  5. Daconil Weather Stik at 5.5 fl oz/1,000 sq ft (curative). 12-hr reentry.
  6. Disarm 480 SC at 8 to 16 fl oz/A. Do not use more than two (2) sequential applications. 12-hr reentry.
  7. Eagle 20 EW at 1.2 fl oz/1,000 sq ft. May produce a growth regulation effect on Kentucky bluegrass. 24-hr reentry.
  8. Heritage at 0.2 to 0.4 ox/1,000 sq ft. Alternate with other fungicides. 4-hr reentry.
  9. Insignia at 0.5 to 0.9 oz/1,000 sq ft. Do not use more than 2 sequential applications or more than 5.5 oz/1,000 sq ft/year. Do not use with organosilicate adjuvants. 12-hr reentry.
  10. Mancozeb 80% (Fore, Manzate, Penncozeb, and Protect DF) at 4 oz/1,000 sq ft. 24-hr reentry.
  11. Propiconazole-based products. 24-hr reentry.
    1. Banner MAXX at 2 fl oz/1,000 sq ft.
    2. ProPensity 1.3 ME at 2 oz/1,000 sq ft.
  12. ProStar 70 WP at 1.5 oz/1,000 sq ft. 12-hr reentry.
  13. Rubigan AS at 8 oz/1,000 sq ft. Apply no more than twice per season 30 days apart. Do not use more than 32 fl oz/1,000 sq ft/year. 12-hr reentry.
  14. Spotrete F at 3.75 to 7.5 fl oz/1,000 sq ft. 24-hr reentry.
  15. Trinity at 0.5 to 1 fl oz/1000 sq ft. 12-hr reentry.
Content edited by: Jay W. Pscheidt on January 1, 2009
 
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