Common Warmer Season Fungus / Disease

Light disease damage-

Light to moderate Lawn Disease, stressful conditions, making fungus more evident

High heat and traffic contribute to stressful conditions, making fungus more evident

Moderate damage-

Moderate Lawn Fungus Disease with Mower Tracks

Most of the time damage will fill in without long term damage. Organic fertilizer steps help suppress this level of damage. Note-lawn mowing has aggravated and spread fungus damage.

Severe Damage-

Severe Lawn Fungus Disease.  Brown circles Dying Grass.

This needs to be stopped with a fungicide. Organic fertilizer along with soil conditioning services, aeration and new, more disease tolerant cultivars (grass) will reduce future damage 

Contributing conditions & treatments


Summer Patch, Necrotic Ring Spot, and Brown Patch are root born diseases that make circles and frog eye shapes. Almost every lawn has had or does have these problems. These diseases are most evident in times of stress, like when it's dry and hot. Conditions such as excessive thatch, poor soil, sod installed over a poorly prepared site and poor cultural practices (mowing and watering) can give these fungus problems all they will need to do serious damage. In most cases, light to moderately damaged areas will recover with minimum long term damage. In severe cases, Fungicide treatments may be needed to stop the damage from getting any worse and rescue the rest of the lawn from infection. Treating light to moderately damaged lawns with a special organic fertilizer and aeration suppresses disease by balancing out soil problems naturally, and is a very cost effective and environmentally friendly long term option


Fungus Problems

There are many different types of fungus that grow in every lawn and it's unlikely that you could eliminate all disease causing fungi, and you wouldn't want to if you could. Many of the fungi that cause turf grass diseases are also important in nutrient cycling, especially in the breakdown of thatch. However, if cultural conditions deteriorate these "beneficial" pathogens can cause serious problems.

Summer Patch / Lawn Cut to Short

Problematic Fungus: What is it?

There are several problematic types of fungus in our area. Some of the most common types include Summer Patch, Necrotic Ring Spot, and Brown patch. The damaged areas can appear as sunken spots of yellow turf that make patches or circles which are sometimes referred to as "frog eye". Damage can be aggravated with stress which can occur in many forms such as the wheels from the mower, which can leave what appear to be tracks of yellow turf behind a few days after it occurs.  In the past Summer Patch and Necrotic Ring Spot were referred to as Fusarium Blight, however, recent research has led to the reclassification of these notorious types of lawn diseases.  

Tracks from mower due to fungus stress

Summer Patch:

Summer Patch is caused by the soil-borne fungus called Mangaporthe Poae. It is commonly associated with grasslands and appears mostly in Bluegrass and Fine Fescue grasses, but can show up in other types of cool season grasses as well. It is a warm weather root disease and grows best in temps between 80-85 degrees Fh and can occur in turf from mid-June through September and reappears during times of hot weather. Summer patches straw-brown splotches range from 6 inches to as much as 3 feet wide growing as the fungus infected areas age. Young roots may appear healthy during the early stages of the disease, but will later show signs of discoloration and rot. Summer Patch moves from plant to plant creeping along roots and rhizomes and spreading at a rate of around 1? inches per week. Recently affected plants on the outer edge of the patch are often a distinct orange or bronze color and patches can even appear more bluish-green. The color is what makes summer patch hard to identify because most people don't notice it until infected plants begin to die. 


Necrotic Ring Spot:

Necrotic Ring Spot is caused by the Leptosphaeria korrae fungus and it is a cool weather root disease. Symptoms are nearly identical to summer patch, however, in contrast to summer patch, Necrotic Ring Spot kills roots in the late spring when soil temps reach 65 degrees and continues through the summer with symptoms appearing in late June and July. Severe fungus damage needs to be stopped with a fungicide.

Brown Patch fungus disease

Brown Patch:

Brown Patch is caused by a fungus named Rhizactonia solani. It is active mostly in warm temperatures and symptoms begin to show under these conditions. 

In Summary:

These "patch diseases" are similar in appearance and management and will likely return to the same areas of the lawn every year. Unless steps are taken to change the conditions in the lawn which lead to the propagation of these diseases they will rapidly spread. For even more detailed information please visit the University of Illinois Extension.

Fungus Prevention

Once the damage has occurred these fungus problems are extremely difficult to control. Preventative maintenance of Fungicides and Organic Base Fertilizer helps balance Fungus naturally with proper cultural practices are the best way to manage these types of lawn diseases

Preventive Fungus control with Organic Fertilizer

Side by side: on the left results with an organic granular time-release fertilizer, on the right results with a standard granular time-release fertilizer

Left organic granular fertilizer -To the Right results with a standard granular

Once the damage has occurred these fungus problems are extremely difficult to control. Preventative maintenance and application of proper cultural practices are the best longterm way to manage these types of lawn diseases. 

Healthy Soil with proper amount organic matter

Organic Fertilizer:

By looking at the picture above, the results speak for themselves. Both yards are fertilized with Granular Time-Release Fertilizer, However, the yard on the left is fertilized with Organic Granular Time-Release Fertilizer. Soil is more important to the overall health of your lawn than any other variable. It has been proven time and again that organics suppress fungus and stimulate healthy micro-organisms. By accelerating and stimulating microbial life (the life blood of rich soil), you can reduce thatch maintenance, increase drought tolerance, and ensure better long term health. Getting your soil closer to the optimum organic state will make a lasting difference.  


> More about Organic Fertilizer <

Disease Suppression


Nearly all of the processes important for the maintenance of healthy turf take place at the microscopic level, including biological control of pathogen and insects, organic matter degradation, nitrogen fixation, and nutrient cycling and chelating. In healthy soil, beneficial microorganisms usually overcome plant pathogens, resulting in reduced damage from diseases and insects.

Certain composted materials have been shown to limit the injurious effects that some disease causing organisms can have on turf grasses.  Sustane fertilizer/soil builders have been compared in various trials to both systemic fungicides and other composted materials. Shown below (and opposite page)  are summaries of trial results. 

Biological Suppression of Various  Turfgrass Diseases with  Compost-Amended Topdressings 

Necrotic Ring Spot Field Study Leptosphaeria korrae Kentucky Bluegrass (Poa pratensis) 1989


Comments:  Organic fertilizers were compared for their ability to control necrotic ring spot in Kentucky Bluegrass. Sustane showed excellent disease suppression.

Summer Patch Field Study Magnaporthe poae Irrigated Annual Bluegrass (Poa annua) 1989


Comments: Organic fertilizers and organic fertilizers + fungicides were compared for their ability to control summer patch in irrigated annual bluegrass. Sustane showed excelled disease suppression. 

Important to think about maintaining proper pH levels

Fungus Disease is most severe in soils with a pH above 6.5. To prevent this disease in turf, first, conduct a soil test to find out what the pH is on your lawn. Then based on what is found in your soil test either sulfur (to lower the pH) or granular lime (to raise the pH) may be recommended to correct the pH of your soil.

  • Sod which has been recently (2-5 years) applied onto poorly prepared soil if improperly applied, sod can lead to poor root penetration.(Examples: rocky soil, heavily compacted soil, clay based soil) Sod also comes with a heavy thatch layer which can hold moisture in and doesn't allow for proper air circulation.

Proper Cultural Practices - *REALLY IMPORTANT*


Proper Cultural Practices

The term "cultural practices" refers to the way you maintain your lawn. Your turf should be maintained in a vigorous but not in an overstimulated growing condition. Any factor that inhibits root growth will increase the likelihood of turf disease.  Some key factors which can help maintain proper cultural conditions include: