WSU Extension

Hortsense

Lawn and Turf : Pythium crown and root rot
(revision date: 6/22/2015)


Biology
Pythium crown and root rot is caused by fungi which can also cause damping-off of new grass plantings. The rot causes a general decline of the turfgrass in patches or in large areas. Symptoms may include poor color, thinning, and slow growth. During the cool, wet conditions which favor disease development, damage may first appear as small, diffuse yellow patches up to 3" in diameter. In warmer, humid weather, damage may first appear as small, brown to tan or bronze areas. Initial patches of either type may coalesce overnight to form large areas of wilted, dying grass. The crowns and roots of infected plants appear watersoaked and root volume and vigor is reduced. Both roots and crowns may be discolored. The fungi typically survive in infected plant tissues and plant debris. They may be spread by infected clippings, contaminated equipment, and water.
Management Options

Non-Chemical Management
  • Good drainage is essential to prevent disease.
  • Provide proper culture including proper fertilization. Do not fertilize heavily in warm, humid conditions.
  • Reduce stress on grass as much as possible.
  • Avoid overwatering. Deep, infrequent waterings are best. Water in the mornings so grass can dry quickly.
  • Remove thatch and aerify as necessary.
  • Collect and remove infected grass clippings to help reduce spread of disease.
  • 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

None recommended

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Caption: Pythium crown and root rot
Photo by: R.S. Byther
Caption: Pythium crown and root rot close-up
Photo by: R.S. Byther