An aerial view shows a modern commercial building complex in Colorado, featuring both vibrant green lawns and noticeable patches of dry, discolored turf. Rocky mountains and forested hills form the backdrop under a clear sky. Published by Wards Lawn, a Colorado-based expert in commercial and residential landscaping services since 1999. This visual directly illustrates the challenge faced by property managers, showing areas of turf that could be either diseased or simply dry, making it relevant to diagnosing commercial turf issues in Colorado. Property managers can learn to distinguish between these turf problems and find comprehensive landscaping solutions by visiting wardslawn.com/commercial-services.

Is Your Commercial Turf Diseased or Just Dry? A Diagnostic Guide for Colorado Property Managers

Fungal diseases cause distinct, unresponsive patches with root rot in commercial turf.

By Dave Ward · June 26, 2026

TL;DR

• Accurately diagnose commercial turf issues by examining patch patterns, soil moisture depth, and roots.

• Drought stress causes uniform, bluishgray wilting that quickly recovers after watering.

• Fungal diseases like Necrotic Ring Spot or Ascochyta blight produce distinct patches or rings that do not respond to irrigation and damage roots.

• Misdiagnosing leads to costly mistakes, such as overwatering fungal infections or applying expensive fungicides to droughtstressed turf.

• Proper diagnosis is crucial to avoid unnecessary expenses and further turf stress in Colorado's heavy clay soils.

Table of Contents

• What Are the Key Differences Between Fungal Disease and Drought Stress?

• How Do You Test Soil Moisture to Rule Out Drought?

• What Are the Visual Signs of Necrotic Ring Spot in Kentucky Bluegrass?

• How Does Irrigation Timing Trigger Ascochyta Leaf Blight?

What Are the Key Differences Between Fungal Disease and Drought Stress?

Fungal diseases and drought stress on Northern Colorado commercial lawns differ fundamentally in their distribution patterns, water response, and root integrity. Drought stress affects broad, sunexposed areas uniformly, causing grass blades to fold and retain footprint impressions, which rebound quickly when irrigated. Fungal diseases manifest as isolated circles, strawcolored patches, or leaf blade lesions that remain dry and brittle regardless of water volume, often accompanied by root decay.

The following diagnostic matrix outlines the physical and behavioral differences between drought stress and common regional fungal pathogens:

| Diagnostic Marker | Drought Stress | Fungal Disease (NRS / Ascochyta) | | : | : | : | | Distribution Pattern | Broad, irregular sweeps; often on southfacing slopes or near hot concrete pavements. | Defined circular patches, donutlike rings, or rapid localized bleaching. | | Footprint Test | Grass blades remain flat and do not spring back after being stepped on. | Grass blades may retain some spring but show physical lesions or rot. | | Irrigation Response | Turf color and elasticity recover within 24 to 48 hours of deep watering. | No improvement after watering; localized patches may actually expand. | | Root & Crown Health | Roots remain firm, white, and securely anchored in the soil. | Roots appear brown, rotted, and the turf pulls up easily from the dirt. |

How Do You Test Soil Moisture to Rule Out Drought?

To rule out drought stress, property managers must measure soil moisture depth directly using a soil probe or a long screwdriver rather than relying on surface visuals. A healthy, hydrated commercial turf profile in Colorado's clay soil requires moisture to penetrate at least four to six inches deep. If the probe slides easily into the soil to this depth and retrieves moist, cool clay, the brown patches are not caused by drought.

Perform these four simple field steps to accurately test soil moisture and determine if underwatering is the root cause of turf discoloration:

• Select the Test Site: Identify a brown patch and select a transitional zone right on the border where the dry grass meets the healthy green grass.

• Insert the Soil Probe: Push a specialized core soil probe or a heavyduty 6inch screwdriver vertically into the turf.

• Evaluate the Resistance: Note how deep the tool penetrates; dry, compacted Northern Colorado clay will completely block the probe within the first inch.

• Examine the Soil Core: Pull the probe out to inspect the soil core for moisture, earthy scent, and root depth.

What Are the Visual Signs of Necrotic Ring Spot in Kentucky Bluegrass?

Necrotic Ring Spot, or NRS, presents as sunken, circular patches ranging from several inches to several feet wide, characterized by a classic "frogeye" pattern. This pattern features a ring of dead, strawcolored Kentucky Bluegrass (Poa pratensis) surrounding a center of healthy, unaffected green grass. Because Necrotic Ring Spot is a soilborne fungus caused by Ophiosphaerella herpotricha, it directly attacks the roots and crowns, leaving them black, brittle, and severely rotted.