WSU Extension

Hortsense

Lawn and Turf : Brown patch
(revision date: 1/22/2016)


Biology
Brown patch is a fungal disease typically affecting bentgrasses and annual bluegrasses. Infected grass appears as patches a few inches to several feet in diameter. The patches are generally circular and light brown in color. Shorter grasses (1/4") may show a "smoke ring" symptom, which is a band of grayish-brown grass about 2" across surrounding the brown patch. A cobweb-like growth of fungus may be associated with the smoke ring in humid weather. Brown patch damage is typically limited to the leaves. Lush turf that is overfertilized and overwatered is more susceptible to infection. Disease development is favored by hot (>82 degrees F), humid weather. Brown patch is relatively rare west of the Cascades and is not common east of the Cascades. The fungus can survive in infected tissues and plant debris of many plant species.
Management Options

Non-Chemical Management
  • Plant resistant grass varieties (see EB0713, Diseases of Turfgrass).
  • Provide proper culture, including adequate, balanced fertilization and deep, infrequent watering.
  • Provide good drainage.
  • Avoid practices which favor disease such as excessive fertilization and watering in hot weather.
  • Water in the morning so grass can dry quickly.
  • Mow regularly at the recommended height.
  • Remove thatch and aerify as necessary.
  • For more information on proper care of lawns, including fertilizer recommendations, see EB0482E, Home Lawns.
Select non-chemical management options as your first choice!

Chemical Management

Follow label directions. Do not repeatedly apply the same fungicide or fungicides with the same active ingredient as tolerant strains may result. Carefully check product labels.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • ferti-lome Liquid Systemic Fungicide II R-T-Spray
    Active ingredient: propiconazole  |  EPA reg no: 53883-184-7401
  • Scotts Lawn Fungus Control
    Active ingredient: thiophanate methyl  |  EPA reg no: 538-88
  • Spectracide IMMUNOX Multi-Purpose Fungicide Spray Conc
    Active ingredient: myclobutanil  |  EPA reg no: 9688-123-8845
  • This list may not include all products registered for this use.
Images
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Caption: Brown patch
Photo by: G. Stahnke
Caption: Rhizoctonia hyphae under microscope
Photo by: G.A. Chastagner