Oh No, There’s a Fungus In My Lawn! What should I do?

April 19, 2024

Turf grass fungus is a challenge to overcome, but by combining mechanical, environmental changes, along with appropriate fungicide applications, the fungal symptoms can be reduced, managed, and often times removed entirely from your lawn.  Each fungus is unique, but there are common practices that can help to overcome those frustrating fungal symptoms throughout your lawn.  Be sure to coordinate with your service provider (like All Green) for fungicide applications, in addition to the mechanical and environmental changes you’ll need to make to your lawn.

Brown Patch Fungus

Patchy green and brown grass texture. The brown patches are caused by a fungal pathogen called Brown Patch

The leaf blades within the patch turn brown after infection, while a gray-white band is often evident at the perimeter of active patches. Remedies for brown patch include aeration to improve oxygenation to the soil, reduce watering times and allow time for the surface to dry out between waterings, don’t apply heavy nitrogen applications in the summer months and apply the proper fungicide where symtpoms are present.  Brown Patch Fact Sheet

Fairy Ring

Grassy turf field with large circular brown ring

Circles of dark green to redish-brown grass, often with mushrooms forming within the band, appear in turf grass. Occasionally the grass dies within the ring. Preventive measures include fertilizing evenly applications. Aeration services can improve oxygenation to the soil to encourage new root development and  help with water absorption. If the problem is severe and chronic, then you may need to kill the grass in that section, rototill, and replant with new grass in the infected areas.  Red Fairy Ring Fact Sheet

Leaf Spot/Melting Out

Close-up of diseased plant leaves with brown spots of leaf spot fungus

Leaf Spot Fungus occurs during the summer months and can be exacerbated by excessive fertilizer applications of quick release nitrogen.  Adjusting watering durations to allow for the surface of the soil to dry out can help reduce fungal spread.  Be sure to bag mow clippings and dispose of them out of the yard.  Also, applications of fungicides can help to reduce the spread of the fungus.  A short mow DOES NOT work for leaf spot fungus.

Melting Out Fungus occurs in April – May, during the rainy, cooler spring weather.  Over fertilization of quick release nitrogen fertilizers in the spring can exacerbate the disease, making it worse.  The use of low nitrogen percentage with slow release formulations can reduce the spread of the fungus. Signs of melting out include cankers on the leaf blades of grass.  Drying out the soil surface and then performing a short mow can remove a lot of the infected blads of grass and reduce fungal spreading.  Be sure to bag the mow clippings and remove them from the yard.  Applying fungicides can help to reduce the spread of the fungus.


Necrotic Ring

Kentucky bluegrass with circular, brown rings formed by necrotic ring spot

Dead circles or arcs that range in size will steady form and spread throughout the lawn over time.  Kentucky Bluegrass is very susceptible to necrotic ring spot.  Aeration in the springtime and fall can help to improve oxygenation to the soil and encourage new root development.  Dethatching, also called power raking, will remove decaying thatch and lawn debris to help reduce food sources for the fungus and reduce it’s spread.  Be sure to water infrequently but deeply. Apply fungicides where the necrotic ring spot shows active symptoms in the lawn. Apply fertilizer at a lower rate where grass is actively growing.  It is important to apply fungicides when the fungus is most active in the spring and the fall.  OVERSEEDING and reseeding are highly recommended every year in the fall.  Be sure to apply fungus resistant blends of new grass seed.  The dead areas will not grow back on their own and will need to be reseed annually, in addition to applying fungicides. Necrotic Ringspot Fact Sheet

Powdery Mildew 

Turf grass with white, powdery mildew fungus growing on the grass blades.

Recognized by white powder on the grass blades (especially in shaded areas of the yard). It’s important to prune trees/shrubs to allow for sunlight.  Be sure to  water infrequently but deeply. Application of fungicides in areas with a history of mildew helps to alleviate symptoms and reduce fungal spread. We also recommend overseeding throughout shaded areas with shade-tolerant grass seed, as those are more fungal resistant and perform better in shaded areas. Powdery Mildew Fact Sheet

Pythium Blight

Pythium blight fungal spores form a fluffy layer around the edges of a section of grass that has died because of the fungus.

Casues irregular shaped spots in grass that often travel along the same path that water travels along the surface of the grass during rain or watering.  When the fungus is active it often shows white fluffly fungal spores around the edges of damaged areas.  It is important to treat for pythium blight with fungicides as soon as symptoms appear to prevent the spread of the damage.  If the spread has already subsided, which can be from application of fungicides or when higher temperatures arrive, it’s important to note that the damaged areas will need to be replaced by either reseeding or resodding those areas. Pythium Blight Fact Sheet

Lawn Rust Fungus

Rust fungus on grass blades close-up.

Rust colored, powdery, fungal spores form on grass blades that turns lawn yellow, orange, red or brown. Its good to allow grass to grow 5 inches and mow to off the infected areas. Be sure to bag  the grass clippings to remove fungal spores and prevent spreading. Dethatcing or power raking will remove too much thatch and decaying lawn debris to help reduce food sources for the fungus.j  Applications of fungicides can reduce the spread of the fungal spores, making it easier to manage with mechanical removal. Lawn Rust Fact Sheet

Snow Mold 

Turf grass with snow mold fungus, which causes a white colored mildew to form on grass blades that eventually kill the lawn.

Snow mold fungus causes patches of grass to die out in turfgrass. Grainy fungal spores are embedded in grass blade tissue and is commonly caused by snow pack compressing the grass blades during the winter months. Apply fungicides in late fall in areas where snow mold has been a chronic problem as a preventive measure. It’s important to avoid piling snow up heavily on top of lawn to reduce the potential of causinig snow mold.  Aside from applying fungicides, mechanical treatments of hard raking the grass and performing a short mow (being sure bag and remove grass clippings) can help to improve symptoms.  Areas that have completely died will need to be reseeded or resodded for recovery. Snow Mold Fact Sheet

Summer Patch 

Bare, brown colored patches on green lawn grass caused by brown patch fungus

Brown patch turf fungus causes circles or arcs that range in size, similar to Necrotic Ring Spot. However, the middle of those circles will more commonly die out, compared to necrotic ring spot. Aeration services can help with oxigenation of the soile and encourage new root development.  It’s important to water infrequently but deeply, allowing the soil surface to dry out in between watering. Be sure to apply fungicide where the disease is showing symptoms.  You will need to reseed or resod areas that have died out completely, as the grass will typically not fill back in on it’s own. Summer Patch Fact Sheet