G1911

Powdery Mildew Disease in Turfgrass

Causes, symptoms and management of powdery mildew disease in turfgrass. This is one in a series of NebGuides on managing turfgrass diseases.

• Introduction
• Cause, Hosts, and Occurrence
• Key Symptoms
• Recommended Cultural/Maintenance Practices
• Fungicide Program

Figure 1. Powdery mildew on Kentucky bluegrass. Note dusty, white appearance on grass blades.

Introduction

Powdery mildew occurs in shady areas of turfgrass. It can be effectively managed by seeding with shade-tolerant grass or by manipulating landscaping so that turf can be in full sun. If these changes aren’t possible, fungicides are available for managing this disease. The following information describes the disease and how to identify and manage it.

Cause, Hosts, and Occurrence

Cause: Erysiphe graminis

Primary hosts: Kentucky bluegrass

Occurrence: May – June, August – October

Key Symptoms

• Grayish white cast to the turf.
  
  
• Individual leaf blades look as though they were dusted with flour or lime (Figure 1).

Recommended Cultural/Maintenance Practices

• Prune shade trees to increase light penetration to the turf area.
  
  
• Remove or thin surrounding vegetation to improve air movement and lower humidity in the grass canopy.
  
  
• Reseed shaded areas with a mixture of mildew-resistant, improved Kentucky bluegrass cultivars and shade-tolerant, fine-leaved fescues.
  
  
• Fungicides (Table I) can be used to manage this disease in high maintenance turf areas. Applications must begin prior to significant mildew development.

Fungicide Program

Fungicides for powdery mildew are presented in Table I. An example product is listed for each active ingredient; other products also may be available. Homeowner and commercial product labels will list active ingredients. While the active ingredient may be in combination with others, users should look for a specific active ingredient with or without other chemistry modes of action.

This publication has been peer reviewed.