NECROTIC RING SPOT FUNGUS
How to Control Necrotic Ring Spot Without Any Chemicals
NRS is Caused by Excessive Watering
Necrotic Ring Spot (NRS) is one of the most frustrating lawn diseases for homeowners due to the abundance of misinformation surrounding its causes and treatments. Primarily, NRS is triggered by excessive watering over a long period of time (months) combined with the use of chemical fertilizers. This combination disrupts the balance of beneficial microbes in the soil, creating ideal conditions for the Necrotic Ring Spot fungus to thrive in low-oxygen environments.
Step #1 – Fix the Watering Problem
If you notice Necrotic Ring Spot on your lawn, it’s an opportunity to address an underlying issue. The first step toward recovery is to reduce the watering, which is key to preventing further damage. Implementing the 1-2-3-2-1 lawn watering technique can help you manage your lawn’s moisture levels effectively.
Step #2 – Rebuild the Soil Microbes
The second step of rebuilding the soil’s microbial population is a much slower process and may take up to 2 years to fully rebuild. This process requires time and dedication, but it will lead to a healthier lawn in the long run. While spores of the Necrotic Ring Spot fungus are found in soils worldwide, areas like Colorado—where sprinkler systems are prevalent—can be particularly affected. Unlike natural weather patterns, which provide variability in moisture, irrigation systems can create conditions that promote NRS. By adjusting your watering practices and focusing on soil health, you’ll be well on your way to revitalizing your lawn.
Soil Recovery Takes Time
Healthy soils are essential for maintaining a vibrant lawn, and one key component is the presence of beneficial microbes. These microbes help stabilize the soil’s microbiome, creating a competitive environment that keeps harmful organisms, such as necrotic ring spot fungi, in check. Without these beneficial microbes, the necrotic ring spot fungus can thrive unchecked, particularly in oversaturated soil, which promotes the rapid spread of its spores.
Full Recovery Takes Approximately
1-2 Years
When a necrotic ring spot outbreak occurs in your lawn, managing it can be a daunting challenge. The recovery process is lengthy, often taking nine months or more. This extended timeline is primarily due to the need to rebuild soil health, which can take anywhere from six months to two years. Without a fully restored microbial ecosystem, the necrotic ring spot fungus will continue to pose a threat. Therefore, having the patience and commitment to this recovery process is crucial for reviving your lawn from necrotic ring spot.
See below for the step by step process to treat a necrotic ring spot infested lawn.
Before Treatment
After Treatments
How to Cure Necrotic Ring Spot in Grass
Should You Apply a Fungicide?
Fungicides are a Bad Idea
Fungicides Kill Both Good and Bad Microbes
When dealing with Necrotic Ring Spot in your lawn, it’s crucial to avoid fungicides. While they do target harmful microorganisms, they also destroy the beneficial microbes. Rebuilding the beneficial microbial population is essential to reclaiming the lawn from the Necrotic Ring Spot fungus. The best approach to curing Necrotic Ring Spot is to foster a thriving, diverse community of beneficial microorganisms. Once the soil and the microbiome is balanced, the microbes will naturally combat the Necrotic Ring Spot fungus spores.
Fixing the Anaerobic Soil Takes Time
The main reason a lawn becomes overrun by Necrotic Ring Spot is because the excessive water caused by the overwatering replaced the air in the soil, and without air the majority of the microbes die. The Necrotic Ring Spot fungus thrive in an anerobic environment which is why they were not also killed by the excessive lawn watering.
Necrotic Ring Spot Spores are In Everyone’s Soils
It’s essential to understand that Necrotic Ring Spot fungus spores are always present in the soil and are not spread by core aeration, lawn mowing, or other lawn maintenance activities. These spores are everywhere; they only pose a threat when excessive overwatering occurs for extended periods. By adjusting your watering habits to follow the 1-2-3-2-1 lawn watering technique and promoting healthy soil, you can effectively manage this problem.
DO NOT Apply a Fungicide!
Photos of Necrotic Ring Spot Lawns
(Click on Images to Enlarge)
How to Cure a Necrotic Ring Spot Infested Lawn?
Step #1: Fix the Lawn Watering Problem (Easy to Fix)
Program the Controller to Follow the 1-2-3-2-1 Technique
The most important step is to address the issue of overwatering the lawn. Necrotic Ring Spot is typically found in areas that are excessively moist or wet, particularly where drainage is poor. To help remedy this, follow the 1-2-3-2-1 lawn watering technique. This method allows adequate time between lawn watering cycles, giving adequate time for the soil to dry out completely. Additionally, it’s crucial to water early in the morning rather than late at night. If overwatering isn’t resolved, the lawn fungus problem will persist. Organo-Lawn will not guarantee curative results for your lawn in the Boulder or Fort Collins area unless an Organo-Lawn employee performs a sprinkler startup or audit.
Furthermore, it is essential to rebuild the beneficial microbial populations in the soil. The fungus will continue to be an issue until microbial activity is restored. Please note that rebuilding the soil takes time; a severe case of necrotic ring spot may take 1-2 years to fully recover.
Step #2: Rebuild the Microbial Population in the Soil
(Takes Time and Difficult!)
Rebuilding the Microbial Populations Takes Time (1-2 Years)
It is essential to rebuild the beneficial microbial populations in the soil. The fungus will continue to be an issue until microbial activity is restored. Please note that rebuilding the soil takes time; a severe case of necrotic ring spot may take 1-2 years to fully recover.
How Exactly Do We Rebuild the Soil?
Lots of Core Aeration
Perform 2-3 lawn aerations, one in early spring, one in late spring, and one in the fall to alleviate soil compaction and introduce air into the soil so the microbes can breathe. Air is vital to establishing a living soil and the more a lawn is aerated the faster the lawn will recover.
Double Aeration is Even Better!
Double aeration is a good idea for lawns with severe necrotic ring spot damage or for people that want to speed up the recovery process.
Remove the Dead Grass
Manually remove the dead grass in the necrotic ring spot circles. You can do this using a heavy metal rake. It takes a little bit of effort, but the lawn will recover quicker if the dead grass has been removed.
Metal Rake
Humate Soil Conditioner
Stimulate beneficial microbial activity by applying Humate soil conditioner 2-3 times per year. Humate will stimulate beneficial microbial activity and help break up compacted soils.
If you don’t have access to a Humate soil conditioner product, try to use a 100% organic soil conditioner or compost as an alternative.
Apply Only High Quality Organic Fertilizers
Avoid chemical fertilizers or anything with a fast release or inorganic nitrogen source. The nitrogen in chemical fertilizers is typically white in color and high in salt. These salt based nitrogen sources kill beneficial microorganisms and will hinder the recover process.
Change all fertilization to organic fertilizers. Chemical fertilizers are high in salts and kill microbes. A very good organic fertilizer for curing necrotic ring spot is Synergy with Corn Gluten Meal.
Proper Lawn Mowing
Never mow the grass when it is wet, and always wait 24 hours after a mowing to water the grass. After a mowing the grass blades have been damaged. It takes 24 hours for a grass to repair the abrasion. If water is added to the lawn before the lesion has time to heal, the fungus can use the water as a transportation mechanism and infect new and otherwise healthy blades of grass. Make sure to mow the grass at 3 inches or taller.
Be Patient!
It Takes 1-2 Years to Recover the Soil
Patience is a key factor for homeowners tackling lawn issues, but it can often be the toughest challenge when dealing with Necrotic Ring Spot. Depending on the severity of the infestation, it may take up to 2 years to fully recover the lawn. The reason for this is because it takes a long time to rebuild the beneficial microbial population in the soil.
Monitor the Progress
If the lawn hasn’t made much progress after following steps 1-6 and a full year has passed since you started treatment, the reason may be that the soil is still lifeless or lacking in beneficial microbial activity. This means that one of the key elements in soil recovery is still not correct.
Air, Water, Food, and Heat
Just like all living things, microbes need 4 basic elements to thrive: air, heat, water (keeping it moist but not waterlogged), and food (organic matter) to thrive. If the lawn is not improving, it is essential to ensure one or more of these vital elements—air, water, heat, and food—are being properly addressed. Overwatering is particularly detrimental and is usually the element that is still out of balance.
Cheical Fertilizers Kill Microbes
If You Aren’t the Patient Type!
Speeds Up Recovery with Compost!
We offer compost top dressing services at an additional charge for customers that want to dramatically speed up the recovery process. We have found that one application of a high-quality compost can enhance the recovery time by up to 2 times faster.
Introduces Millions of Beneficial Microbes
The reason that compost top dressing is so effective is because a high-quality compost is already teaming with millions of microbes. Therefore, instead of rebuilding the microbial populations naturally, the compost top dressing will introduce the microbes organically.
Remember…. Avoid Fungicides!
Fungicide Applications Kill Microbes and Microbes are What We are Trying to Rebuild
Using fungicides to treat Necrotic Ring Spot (NRS) can often do more harm than good. While fungicides may temporarily suppress the fungus, they do not address the root cause of the disease—poor soil health, compacted conditions, and imbalanced microbial populations. Overuse of fungicides can kill beneficial microbes that naturally help suppress the disease, further weakening the soil’s ability to recover. Additionally, NRS is primarily a stress-related disease, meaning that improving soil aeration, increasing organic matter, and maintaining proper watering practices are far more effective long-term solutions. Rather than relying on fungicides, focusing on soil health and plant resilience is the best way to manage and prevent Necrotic Ring Spot.
Build the Soil with Organics
Typical Treatment Schedule for
Necrotic Ring Spot
Early March: Single or Double Aeration and Synergy Application
Mid April: Sprinkler Audit and Humate Soil Conditioner Application
Mid May: Single or Double Aeration and One Earth Weed Control Application
Late June: Synergy Application and Humate Soil Conditioner Application
August: Synergy Application
Early September: Single or Double Aeration and Humate Application
October: Single or Double Aeration and Synergy Application
Optional Addition (Any Time of Year)
Compost Top Dressing (Compost Top Dressing Speeds Up Soil Recovery by 2X)
Do You Need Help Fixing a Necrotic Ring Spot Lawn?
Treating necrotic ring spot fungus may seem straightforward; however, correcting the watering practices can be complicated.
Boulder (303) 499-2000
Fort Collins (970) 225-9425
Photos of Necrotic Ring Spot Fungus – (Click on Images to Enlarge)
Necrotic Ring Spot
(~1 Year Recovery)
Mild NRS
(~1 Year Recovery)
Average NRS
(~1 Year Recovery)
Severe NRS
(~2 Year Recovery)
Extreme NRS
(~2 Year+ Recovery)
Very Severe NRS
(~2 Year Recovery)
Early Stages of NRS
(~1 Year Recover)
Severe NRS
(~2 Year Recovery)
Young NRS
(~1 Year Recovery)
Necrotic Ring Spot Treatment FAQs
How to Fix a Necrotic Ring Spot Lawn?
To effectively address Necrotic Ring Spot, it’s essential to focus on eliminating the underlying cause rather than simply treating the symptoms. Infestations of Necrotic Ring Spot fungus in a lawn typically indicate that the lawn has been overwatered for an extended period. Severe overwatering creates an anaerobic environment in the soil, displacing air and allowing only certain types of soil microbes to thrive.
Fixing the Lawn Watering Issue is the Most Important Step
To remedy the fungal problem, the most crucial step is to water deeply but infrequently, following the 1-2-3-2-1 lawn watering technique. Creating a living soil rich in microbial activity is key to curing Necrotic Ring Spot. A diverse and competitive microbial population in the soil contributes to a healthier lawn.
Stick with the Plan!
Effective lawn care practices to help heal Necrotic Ring Spot without the use of chemicals include using humate soil conditioners, performing lawn aeration, and mowing properly. It is important to avoid applying lawn fungicides to areas affected by Necrotic Ring Spot, as these products can eliminate both harmful and beneficial microbes in the soil, which is counterproductive to curing the fungal issue.
The recovery time from Necrotic Ring Spot (NRS) depends on the severity of the condition. If the NRS is mild, it typically takes 3 to 6 months for the disease to resolve. However, in severe cases, it may take 1 to 2 years for the lawn to completely recover from all symptoms. We have found that applying compost top dressing alongside the regular treatment plan can accelerate recovery, reducing the time needed by approximately half.
We have found that the only way to guarantee results is to perform all of our services ourselves. The most challenging part to get right is the sprinkler audit. Additionally, we have noticed that when other companies handle the core aeration, the results are not as effective as when Organo-Lawn performs the aeration.
The improvement of a lawn affected by Necrotic Ring Spot depends on the time of year treatment begins and the severity of the damage. If treatments are started during the summer months, the lawn may initially appear worse before it starts to improve. This occurs because adjustments to the lawn’s watering schedule can temporarily lead to a decline in appearance before any positive changes take place.
Generally, we’ve observed that in the first one to two months, the lawn may look worse or show little to no improvement. However, with time, it will gradually start to recover. Patience is crucial when successfully treating a lawn infested with Necrotic Ring Spot.
Technically, yes, but in reality, no. Aerators pull plugs of soil from the ground, and if these plugs contain the fungus, it could transfer spores to other areas of the lawn. However, for the fungus to establish itself in a new lawn, the watering conditions would have to be excessive, creating an environment ideal for Necrotic Ring Spot (NRS) to take hold. NRS fungi thrive in anaerobic conditions, where the soil is heavily saturated and lacks oxygen. Therefore, a healthy lawn would not develop Necrotic Ring Spot just because a plug from an aerator was introduced into it.
Avoid using fungicide on lawns affected by Necrotic Ring Spot. These chemicals can disrupt the balance of both beneficial and harmful microbes in the soil. Instead, concentrate on nurturing the beneficial microbes, as they will help outcompete and eliminate the harmful ones, ultimately restoring your lawn’s health.
Many chemical lawn care companies focus on treating the symptoms rather than resolving the underlying issues. Unfortunately, the products they use often harm the beneficial microbes that are essential for healthy soil. Both fungicides and chemical fertilizers can kill these important organisms. Without revitalizing the population of beneficial microbes, a lawn suffering from Necrotic Ring Spot will never fully recover. It’s crucial to adopt a holistic approach to lawn care that fosters soil health and addresses root causes for lasting results.
If you’re dealing with Necrotic Ring Spot, it’s a sign that your watering practices need attention. We’ve heard from hundreds of customers who faced the same issue, and in every case, a thorough evaluation of their sprinkler systems revealed a problem with overwatering. By correcting this, you can restore the health of your lawn and prevent further damage!
You don’t need to remove soil or sod from a lawn to treat Necrotic Ring Spot. The solution lies in addressing the underlying causes, which are always severe overwatering and a lack of beneficial microbial activity in the soil. By correcting these two issues, your lawn will no longer be prone to developing Necrotic Ring Spot.
We have discovered that applying compost as a top dressing will introduce billions of beneficial microbes into the soil. This can significantly accelerate the recovery of the lawn, provided that the necessary conditions to support these beneficial microbes have been addressed. Specifically, proper lawn watering practices should be in place, and core aeration should have been performed.