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How To Control Necrotic Ring Spotnecrotic ring spot

You may be thinking that as long as you water your lawn, you are doing a great job in lawn maintenance but when diseases such as necrotic ring spot creeps onto your lawn, it may lead you to rethinking your lawn care regimen. This unsightly lawn disease appears in the form of small, patches light green in color which grow and turn reddish brown in color, appearing in streaks and circular patterns around a center of relatively healthy green grass.

Necrotic ring spot infests lawns across the country, particular during cool weather and wet weather and creeps up more often in places that are not well-fertilized. There are various reasons that necrotic ring spot may appear on your lawn but for the most part, it usually occurs through over watering or poor mowing practices.

If left untreated, necrotic ring spot can begin to spread through spores and can overtake a lawn. Common types of grass that can be severely affected by necrotic ring spot includes kentucky bluegrass and bentgrass as well as ryegrass, red fescue, tall fescue and Chewings fescue

If you have discovered necrotic ring spot on your lawn, this is a definite cause for concern and moving forward with a treatment program is essential. At Solutions Pest and Lawn we have not only products which can effectively take care of this troublesome lawn disease, but we can also equip you with the correct treatment approach so you can easily remove this problem from your lawn.

Browse our necrotic ring spot control products below. If you have any questions or concerns, send them our way via email, phone, or online live chat and we will be happy to assist you.

How To Get Rid of Necrotic Ring Spot: 3 Step Solution

Unlike some of the more common lawn disease, necrotic ring spot can be a very difficult disease to control. That’s why it is better to put into place preventative measures so necrotic ring spot doesn’t appear on your lawn to begin with. However if necrotic ring spot is on your lawn you either have to dig out the infection and reseed or fight the disease with the help of fungicides. Here we have laid out three basic steps to tackle this troublesome lawn disease.

Step One: Before proceeding with control, it is important to correctly identify the lawn disease and be certain that it is necrotic ring spot. Correctly ID’ing the disease can then help you to choose the right fungicide that is specifically designed to treat the disease. Necrotic ring spot develops symptoms which resemble another lawn disease such as summer patch blight which may result in confusion over which disease your lawn has.  

If you are not certain what lawn disease you have, we can help. Take a photo of the diseased area of your lawn and send it along to
identification@solutionsstores.com and we will respond back with a correct ID of the fungus and recommend you products and tips to treat the disease correctly.

Step Two: Once the disease is properly ID’d as necrotic ring spot, you can move on to control. We have a number of different fungicides which can effectively treat and remove necrotic ring spot (our recommendations are found below), the preference of what fungicide you choose is up to you. The most important factor when treating this lawn disease is to act quickly. Spray the affected areas immediately with your fungicide of choice.
You may have to re-apply fungicides a few times to provide continuous control of necrotic ring spot. Retreat if you begin to see symptoms again.

We also suggest wearing the proper safety equipment for the job to prevent chemicals from coming in contact with your eyes or skin. Gloves, safety goggles and long sleeved clothing should suffice.

Step Three: Once the necrotic ring spot has been wiped out from your lawn, you must work to keep it from coming back by practicing organic control measures and routine maintenance. One of the main reasons this disease creeps up is overwater. Maintain your soil moisture levels by not watering too much too often. Keeping plants healthy by providing proper light and feeding your lawn with fertilizer will strengthen the plant’s ability to ward off a fungus attack.


Learn More About Necrotic Ring Spot

To the layperson, the term “necrotic” means death, and that’s exactly what necrotic ring spot brings once it has set foot on a turf. Death to all grass if there is no type of intervention plan put into place.


Necrotic ring spot is caused by a Leptosphaeria korrae, a fungus known to infects the roots of turf. Necrotic ring spot is known to infect popular lawn grasses such as Kentucky bluegrass and annual bluegrass on golf courses, sports turf, professional landscapes, and residential lawns.


While necrotic ring spot is not regarded as a destructive disease since it doesn’t kills large areas or grass, an outbreak of the fungal disease on a turf can mess with the appearance of the grass and make it unsightly to look at or use as a playing surface.


Playing fields and landscapes which have a mixture of annual bluegrass and creeping bentgrass may suffer from a blotchy or scattering appearance as a result of necrotic ring spot taking hold on the land. Necrotic ring spot often is seen as a disease of turfgrass that is on the younger side, but disease development can also occur in older turf (30 years or more)


Why it may happen is possibly due to fungal spores in the air which can actually lie dormant for 30 years and all of sudden become active and infect your lawn with the disease.


Have A Lawn Issue That Isn’t Necrotic Ring Spot? Check out Our Lawn Care Main Category!

Characteristics of Necrotic Ring Spot

When necrotic ring spot is present, it is usually when the weather is cool and wet around the spring and fall season. The symptoms of the disease initially appear as small clustered patches of gray-tan colored turf between 6 to 8 inches in diameter.


Due to necrotic ring spot being a root disease, initial above ground symptoms include discoloration from the leaf tips followed by collapse of the leaf and decline of the entire plant. Infected roots are affected by stunted growth and look worn and dead compared to healthy roots.


Close inspection of infected roots will reveal the presence of numerous runner hyphae . Over several years, patches grow bigger and turf that was not killed at the initial outbreak site will recover, giving the affected turf what is known as a ‘frog eye’ symptom.


The pathogen from necrotic ring spot has the ability to survive as mycelium in dead and decaying root tissues. The disease then spreads via the transport of soil with infected roots, primarily through lawn care duties such as core aeration. Infection occurs during cool wet periods in spring and fall months when the temperatures are between 60 and 75 degrees.


However, symptoms of necrotic ring spot may persist well into the summer months, as plants with root systems infected by the fungi go through drought stress. The presence of necrotic ring spot symptoms in summer often leads to people mistaking the disease with summer patch.


Make Sure You Have The Right Equipment For The Job. SHOP For Sprayers and Other Lawn Care Essentials


Types Of Grass Which Can Be Affected By Necrotic Ring Spot


Necrotic ring spot can become a serious problem on Kentucky bluegrass and bentgrass, and also can do quite a number on ryegrass, red fescue, tall fescue and Chewings fescue. It usually appears in late winter, spring and fall during periods of cool and wet weather. Activity is more prevalent in areas that are not given adequate fertilization, and necrotic ring spot lawn disease also tends to show up year after year in areas that have been infected before.


On the other hand, there apparently are a few Kentucky bluegrass varieties which can be somewhat resistant to necrotic ring spot. As a result, it is advised to track down those varieties or use another turfgrass species, such as perennial ryegrass (Lolium perenne) for overseeding damaged areas in the fall. The Kentucky bluegrass types known as America, Majestic, and Midnight are among a number of grass varieties which show moderate resistance to the disease.


Cultural Practices to Prevent Disease


Cultural control practices are targeted towards minimizing the effects of necrotic ring spot infection. Management practices that promote deep rooting during spring and fall will help reduce the extent of necrotic ring spot symptom expression.


Also, the effects of infection will be reduced with practices that are designed to relieve summer stresses associated with compaction, drought, and nitrogen deficiency. These include implementing a balanced nitrogen fertilizer program (preferably with slow-release sources of N), re-directing traffic where feasible, and judicious use of irrigation. Although there are differences of opinion, most researchers favor the use of deep and infrequent irrigation and/or syringing as part of a program to reduce the effects of summer stress on infected turf.


Watering should be conducted all through the summer, frequently and lightly due to shallow root systems. Water 3 to 4 times a week for a total of one inch (along with rainfall). Something that can also help is a light mid-day watering where you spray just enough to wet the leaves. This can help the plants tolerate heat stress during days with very high temperatures.


Once the dead grass recovers, or in the fall when conditions are cool and wet, return to a regular watering schedule of one inch per week or half an inch twice per week, depending on soil type and amount of rainfall.


There may be times when you need to reseed your turf. While dead rings of grass caused by necrotic ring spot will typically recover when fall arrives and when plants are not experiencing heat and drought stress. This is when the fungus activity tends to die down.  However, poor lawn care maintenance will benefit the disease causing rings to develop again in the spring.


Reseeding dead areas with resistant varieties of bluegrass may aid in the recovery process. As noted earlier, there are a number of different varieties of Kentucky bluegrass available which can be resistant to the threat of necrotic ring spot. These include Adelphi, America, Eclipse, Kelly, and Midnight. Be careful when using herbicide products during the reseeding period, since most can damage grass seed. Resodding areas which have been damaged by the disease is not recommended since it hardly makes a difference. New sod is usually reinfected.

READ MORE: 5 Tips For A Thriving Lawn By The Sumo Gardener!


Chemical Control Methods For Necrotic Ring Spot Control

To successfully control necrotic ring spot through the use of chemical you will need to conduct a timely application of systemic fungicides in spring.


Preferred fungicides include Patch Pro Fungicide and Strobe 50WG Systemic Fungicide or Heritage Fungicide. Sprays should be applied when weather conditions favor pathogen activity in the soil, for example when soil temperatures at the 3” depth range between 60 - 70˚F.


The best time for those temperatures to first come up in the soil is usually late May to early June, so make an application at that time. A month later a second application should be conducted. You can also apply preventative application of fungicides in the fall (preferably in September), but spring applications are much more effective.


Due to fungicides needing to reach the roots in order to be effective, practices that facilitate delivery of the fungicide to the root zone may result in improved fungicide performance. These include watering the turf before and after fungicide application and aeration before applying the fungicide treatment.


Fungicides will most likely need to be applied for several years until disease symptoms subside.


Better Safe Than Sorry: Equip Yourself With Protective Safety Equipment Before Spraying


Preventing Necrotic Ring Spot From Returning

If you don’t want necrotic ring spot to make a comeback on your lawn, there are a few things you can do to lessen the chances of a reinfestation. Core aeration or deep tine aeration in spring or fall will encourage deep rooting, improving the chance of turfgrass survival and recovery.


Relieving summer stress through a regular watering routine, implementing a balanced nitrogen fertilizer program, and raising mowing heights to 3” will reduce demands on the root system and help lessen the chances of turf decline during hot dry conditions.


Fungicide re-application should be considered only if other options have been thoroughly exhausted, and then should be contracted through custom spray applicators.


Additional Resources:


Necrotic Ring Spot | Texas Plant Disease Handbook


Necrotic Ring Spot - Purdue Extension - Purdue University (PDF)


Necrotic Ringspot and Summer Patch - Missouri Botanical Garden

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