Lawn Disease – Pythium Blight

(Pythium aphanidermatum)

Pythium Blight – sometimes referred to as Pythium Root Rot – is a common turfgrass disease of highly maintained turf. Pythium Blight can affect a variety of turfgrass species throughout the United States, although is much more common in the southern states. Pythium Blight damage occurs during summer months in the northern states and from early fall through late spring in the southern states.     

Identifying Pythium Blight -

Pythium Blight causes greasy, brown, circular spots that are 3/4 of an inch to 2 inches in size, growing rapidly. These spots are water soaked and dark colored early in the morning. They will produce cotton like masses of mycelium and they may combine to form larger patches. Areas of your lawn infected with Pythium Blight may appear bronze to orange in color, collapse and die.

Pythium Blight will appear suddenly during hot, humid weather and is common in the wettest areas of turf and in the surface drainage pattern. It is most severe on immature turfgrass and seedlings and is not commonly found in home lawns.

Conditions for Pythium Blight Infection -

Pythium Blight can only lead to an infection in your lawn if all of the following conditions are present:

1. Pathogen – Pythium aphanidermatum

2. Host – Annual bluegrass, bentgrass, bermudagrass, perennial ryegrass and tall fescue

3. Environment – Hot, humid climates with temperatures in excess of 90 degrees Fahrenheit in the daytime, 68 degrees nighttime; high nitrogen soils

Pythium Blight Control -

Cultural disease control practices create favorable conditions for a healthy lawn, and often create unfavorable conditions for the growth of Pythium Blight. Environmental conditions cannot be changed, but cultural practices performed by the homeowner can be modified to lessen the chance of extensive damage from Pythium Blight. Scotts LawnService can help determine a plan for preventing and controlling Pythium Blight in your lawn.

For Pythium Blight control and treatment, Scotts LawnService recommends the following cultural control tips:

  • Avoid mowing wet, infected turf where mycelium is present to avoid spreading spores with the mower blades
  • Reduce thatch and improve drainage with core aeration
  • Increase air circulation and reduce the amount of shade which will limit the amount of time of foliar wetness
  • Infrequent deep watering is recommended verses frequent shallow watering
  • Avoid watering at night

Scotts LawnService has professional products that can prevent and control lawn diseases when cultural control practices are not effective.

Scotts LawnService is the trusted industry leader for professional quality lawn care. Our exclusive lawn care products include premium grass seeds and professional-grade fertilizers; our lawn service teams are comprised of highly trained, industry-certified professionals. Contact a representative today for Pythium Blight control options available in your area and to learn how you can enjoy a lush, thicker lawn that only Scotts LawnService can deliver.