Colorado Lawn Specialists
Working Together with You!
Colorado Lawn Specialists
Working Together with You!
Colorado Lawn Specialists


What is Necrotic Ring Spot or NRS?

Necrotic Ring Spot (NRS) is a fungus, characterized by "fairy rings" or circular patches of dead turf. NRS fungus attacks the roots of your lawn, making the turf incapable of absorbing moisture and nutrients. Areas affected by this fungus will gradually lighten in color and eventually die. Necrotic Ring Spot is a perennial fungus which means that while some recovery can be seen in the cooler months, if left untreated it can return and intensify in subsequent years.

If you suspect you have NRS, one of the most important things we suggest is to avoid overwatering the turf. It might look dry but excess water is prime breeding ground for fungus. If you water in the early morning hours you may want to begin watering closer to sunrise so that the heat of the day can burn off any excess water. Aeration is also recommended to loosen soil compaction and avoid hydrophobic soil.

We typically recommend two applications of a professional grade fungicide to treat NRS. Occasionally areas that are infected with NRS may take several treatments or even several seasons to manage effectively.

If the damage is severe, we recommend power raking to remove thatch (the fungus lives on dead roots) and overseeding with one of several different varieties of turf grass that are particularly resistant to NRS.

What is Ascochyta Leaf Blight?

Ascochyta Leaf Blight is a fungus that is becoming more common in Colorado's Kentucky bluegrass lawns. Ascochyta can develop at any point in the growing season, but is especially prevalent during periods of high heat and drought conditions. It is characterized by the grass leaves dying back from the tip (as opposed to from the root to the tip) and may cause large, irregular patches of straw-colored turf. Ascochyta symptoms can appear similar to drought stress.

Ascochyta Leaf Blight control is comparable to other fungus management in that it is suggested to maintain uniform moisture on the lawn and avoid overwatering. If your lawn is affected by Ascochyta, we recommend watering in the morning rather than at night so that the heat of the day can help evaporate any excess moisture. If you fertilize, you will want to fertilize regularly using low nitrogen fertilizer and have your lawn aerated to ensure maximum water penetration into the soil. Power raking is also a tool to help control Ascochyta since the fungus spores likely survive in thatch. It is helpful to keep your grass height around 3 inches, use sharp mower blades to avoid "wounding" the turf and never mow when the lawn is wet. These recommendations can help limit the amount of damage from the fungus along with preventing future disease development.

We offer a commercial grade fungicide that can inhibit Ascochyta growth and can make other recommendations to help create a healthy and beautiful lawn.

Fungicide Program

We offer a fungicide program to target the specific fungus affecting your lawn and can make additional recommendations to help create a healthy and beautiful lawn.

What a Transformation:
Fungicide 1
Fungicide 2

The purpose of the fungicide is to prevent the fungus from spreading/worsening. More often than not, the lawn will recover on its own over time. In more severe cases, power-raking and/or slit seeding may be needed. Here are a few tips to help your lawn:

  • Avoid over-watering
  • Avoid watering at night, instead, water in the early morning hours so that the heat of the day can help to evaporate any excess moisture
  • Do not mow too short, aim to keep grass height around 3"
  • Sharpen mower blades to avoid "wounding" the grass
  • Do not mow when turf is wet

Note: After fungicide has been applied, the lawn needs to be watered for 20 to 30 minutes per zone to activate the product. Please allow the lawn to dry thoroughly before allowing people or pets on the treated area.

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