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How To Control Pythium Blightpythium blight

Some of the worst lawn diseases are ones the you don’t notice until the damage is painfully obvious. This can be the case with pythium blight which is a highly destructive turfgrass disease. If left untreated, pythium blight can spread around your lawn, killing off your turf which will result in a lot of labor and expense needing to be shelled out to restore your lawn.

Pythium blight is also known as cottony blight, spot blight or grease spot, and affects grass in the summer when the temperature as well as the humidity is considerably high. Grasses infected with pythium blight often go undetected by lawn owners because in the early morning, turf infected with pythium appears to look wet with dew and darkly colored green. This in fact is not the case and it may be due to the greasy or oiliness of infected grasses.

When the weather becomes hotter, this infected grass begins to wilt at an alarming rate, turns brown and then dries and dies out. In other cases, a sign of the disease is white, cobwebby, mold-like growths of the fungus appearing on the leaves and blades of grass. At worst case, the solution to fighting the disease is changing your grass entirely and starting from scratch which may not be ideal with how time-consuming and expensive that would be.

If you have pythium blight on your lawn, you will need the help if fungicides to eradicate them from your lawn. Solutions Pest and Lawn can provide you with the best fungicides on the market and on top of that, we will show you how to apply them so you get maximum results.

Browse our pythium blight 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 Pythium Blight: 3 Step Solution

Unlike some of the more common lawn diseases, pythium blight can be a very difficult disease to control. That’s why rather than fighting the lawn disease when it appear on your lawn, it’s better to set preventative measures so the disease doesn’t appear on your lawn to begin with. Fungicides are often seen as a last resort. However if pythium blight has established itself on your turf, it’s not a hopeless battle trying to remove this stubborn disease--if you have the right product. 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 pythium blight. Often, diseases are confused or misdiagnosed as other diseases which can muddy up the fungicide selection process. Correctly ID’ing the disease can help you to choose the right fungicide that is specifically designed to treat the disease. Pythium blight has some clear cut characteristic which you can spot but 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 pythium blight, you will need to select a fungicide which is ideal to treat this lawn problem. We have a number of different fungicides which can effectively treat and remove pythium blight (our recommendations are found below). What’s most important when applying any fungicide you select is timing and attacking the disease in its early stages. 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 pythium blight. You may need to reapply the application after a period of 7-14 days to ensure the pythium blight is totally eradicated.


Step Three: Once the pythium blight has been removed from your lawn, you must keep it from coming back by practicing organic control measures and routine maintenance. Control practices for residential lawns are based on avoiding excessive nitrogen fertility during the summer season, avoiding early evening irrigation, and improving air circulation to hasten drying of leaf surfaces.


Learn More About Pythium Blight

Pythium blight is often caused by various pythium species such as pythium aphanidermaturm, pythium graminicola, pythium ultimum and pythium vanterpoolii. It is a serious disease of cool season turf grasses during hot humid weather.


Common names associated with pythium blight include cottony blight and grease spot. On short cut turf like a creeping bentgrass, putting greens or fair ways, the disease initially appears as orange colored spots. In the early morning, a light gray ring may or may not be present along the outer edge of the spot. The spots are typically 1 to 3 inches in diameter.


If humidity levels remain high, especially at night into early morning, a white fluffy mass of mycelium can occur. Sometimes this is called the cottony blight phase. If conditions remain favorable, the spots may enlarge quickly within hours and coalesce. In the presence of free moisture, like within drainage patterns, streaking may occur.


On higher cut turf, such as perennial ryegrass turf, large spots appear and they can also streak. Although pythium blight occurs primarily on cool season turf grasses,  it can also occur on warm season grasses.


As previously mentioned, hot, humid conditions are extremely favorable for pythium blight. It’s rapid spread is enhanced with the presence of free moistures. Pythium blight can cause extensive damage under wet conditions and temperatures between 86-95 degrees fahrenheit


Have A Lawn Issue That Isn’t Pythium Blight? Check out Our Lawn Care Main Category!

Which Grasses Are Most Susceptible To Pythium Blight?

Creeping bentgrass, annual bluegrass, rough bluegrass and perennial ryegrass are the grass types most vulnerable to damage by outbreaks of pythium blight. The pythium fungus can also affect to kentucky bluegrass and tall fescue, but the development of the disease is minor and is usually not significant enough to cause damage to these plants.


Pythium blight gains a lot of attention compared to other common fungal lawn diseases because of how quickly it is able to spread where it is established and how quickly it can affect leaves and crowns as well as kill plants off, resulting is considerable loss to the turf.


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Ideal Conditions and Signs of Pythium Blight

Pythium blight thrives in areas during the most unpleasant days of summer when dew periods are long (usually more than 14 hours in duration) and night temperatures reaching an average of 68 degrees or more. The initial presence of pythium blight are usually first noticed in low areas of turf where soil moisture is higher and dew begins to form early in the evening and lasts into the next morning.


Rainfall in late afternoons during hot humid temperatures allow for the disease to develop even further and may be a key factor in the pythium blight pathogen spreading. Grasses that are growing lush and have nitrogen content are especially susceptible to being infected by the disease.


When the temperatures are high and it is hot and humid, a homeowner should be on alert for possible outbreaks of pythium blight. The first signs of the disease may be small, circular spots of collapsed, wet looking leaves and stems on grass that has been mowed short. When examining in the early morning, you may notice plants that possess the disease to have cottony white mycelium fungus growing on the plant. This turf will eventually die and become matted.


If the ideal conditions for pythium blight thriving persist and there is no efforts to intervene and hinder the development of the disease, you may notice big areas of grass that will soon be killed in just a few short days.


The Pythium fungus typically overwinters in the soil and in leaf litter. It is able to spread via the movement of water. When water runs off through areas of turf that contain the disease, spores of the disease can be transported via the water. Also, pythium blight fungus can also be spread via lawn equipment, for example, via lawn blades after mowing while the grass is still wet.


Cultural Control Options For Pythium Blight

As with most fungal diseases which emerge onto a lawn, it’s much easier and more effective to prevent a disease from establishing itself onto turf rather than trying to get rid of a disease or fungus after it’s already been well established.


Environmental modification is the best way to lessen the severity of pythium blight. Cultural practices should be put into place with the purpose of minimizing the presence of excessive moistures such as improving drainage and avoiding overwatering. Excess water around areas should be addressed to avoid waterlogged root zones.


Excessive thatch should be controlled since pythium spore populations are enhanced by the presence of thatch. Carrying out tasks such as selective pruning of trees and shrubs and using fans can help to circulate air better on the turf and dry the surfaces of turfgrass, making it the dew period is lessened in duration.


Lessening the amount of nitrogen in your turf can also help in keeping your grass less susceptible to pythium blight outbreaks.


Due to pythium blight’s knack for surviving and spreading characteristics, the outbreak of this fungal disease often occur in the same “problem” areas every year as hot weather conditions take hold. Hold back from mowing in those areas until surfaces are dry. Laying out a preventative spot treatment with fungicides in those areas is recommended.


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Using Fungicides To Control Pythium Blight

Due to how quickly pythium blight can establish itself on a turf and spread and how the disease has a tendency to cause death to a lawn, the use of a fungicide may be an essential tool in saving your lawn and getting pythium blight under control. Fungicides should be put down in anticipation of the extreme heat of summer.


Depending on the history of the disease on your turf, you may either need to do a full broadcast spraying on your lawn or you may merely need to spot treat certain areas which have in the past shown susceptible to contracting the pythium blight disease. If it is particularly hot and humid in your region of the country, repeated applications of a selected fungicide may be necessary.


When selecting a fungicide, it is vital to be able to accurately diagnose and identify the disease on your turf as being pythium blight because there are specific fungicides which target this disease and will not be effective to other types of fungal lawn diseases.


As a result, differentiating pythium blight from other disease which commonly occur in the summertime such as anthracnose, brown patch, dollar spot and summer patch will be important. If you need help properly identifying the lawn disease on your lawn and getting confirmation that it is indeed pythium blight, you can take a close up photo of the disease and send it to our email at identification@solutionsstores.com. We will respond back to you promptly with the correct ID of the disease as well as offer fungicide options which will be best for you to use.


Products which contain Mefenoxam (such as Subdue Maxx Fungicide) and azoxystrobin (Heritage G Fungicide) are proven materials when have demonstrated to be very effective against Pythium blight. Cyazofamid (Segway Fungicide) and Metalaxyl (Regulate Select) are new products that reportedly are also very effective. Other products we have listed may be effective only when applied as a preventative and only when disease pressure is low to moderate.


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In conclusion, pythium blight is a warm weather disease that is especially severe in areas that are water saturated or that free water can occur. Preventative management is the most effective means of control.


Pythium blight is a major threat to perennial ryegrass lawns. Areas which do not have enough air flow are most susceptible to being infected. Control practices for residential lawns are based on avoiding excessive nitrogen fertility in the middle of summer, avoiding early evening irrigation, and improving air circulation to speed up drying of grass surfaces. If extensive Pythium blight turf damage occurs yearly, over-seeding or reseeding affected areas with Kentucky bluegrass or tall fescue may be your best option to take as they are most resistent turfgrasses.


Additional Resources:


(PDF)Pythium Blight of Turfgrass - UNL Turf - University of Nebraska–Lincoln


Pythium Blight of Turf - Missouri Botanical Garden


[PDF]Pythium Blight of Turfgrass - K-State Plant Pathology - Kansas State


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