WSU Extension

Hortsense

Lawn and Turf : Leaf spot
(revision date: 6/22/2015)


Biology
Fungal diseases of turf caused by Drechslera sp. include leaf spot and melting-out, root, crown, and rhizome rots, and net blotch. Leaf spots first appear as small, water-soaked areas that soon become uniformly dark (reddish-brown to purplish-black). In severe cases, this results in severe thinning of the lawn and is termed "melting-out". Root, rhizome, and crown rots caused by Drechslera sp. cause plants to display symptoms of wilting and yellowing, followed by browning and death of plants. Net blotch appears as a fine network of short brown streaks that lie both parallel and perpendicular to the leaf axis. The fungi can survive in diseased plant debris or on infected plants. The disease is spread by infected clippings, contaminated equipment, wind, or splashing rain.
Management Options

Non-Chemical Management
  • Plant disease-resistant cultivars (see EB 0713, Diseases of Turfgrass).
  • Provide proper culture including adequate (but not excessive) fertilization.
  • Mow to proper height and remove clippings.
  • Water in the morning, so grass can dry quickly. Deep, infrequent waterings are best.
  • Remove thatch and aerify as needed.
  • Do not grow turfgrasses in heavily shaded areas if Drechslera diseases are a problem.
  • For more information on proper care of lawns including mowing heights and fertilizer recommendations see EB0482E, Home Lawns.
Select non-chemical management options as your first choice!

Chemical Management

Fungicide applications to home lawns is not recommended because damage usually is done before the disease is noticed.

Images
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Caption: Drechslera leaf spot
Photo by: R.S. Byther