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How To Control St. Augustine Decline

St. Augustine grass is one of the most popular types of turf grasses to choose to grow on a lawn. It is widely used in the southern states and is regarded as a medium to high-maintenance grass. Because of this fact, if a lawn owner doesn’t keep up with routine care of the grass, it could be subject to rot and disease such as St. Augustine Decline, also know by a fitting acronym, SAD.

St. Augustine Decline (SAD) is a viral disease which results in a chlorotic mottling or stippling of St. Augustinegrass leaves. St. Augustinegrass and centipedegrass are the only lawn grasses which the virus is known to affect. The virus is mostly found on landscapes in Texas but there has been instances of the disease reported in Louisiana and Arkansas.

The symptoms of SAD begin with a slight gradual yellowing of the grass blades and end with almost complete die-back within three years. In that time usually bermudagrass takes over wherever St. augustine grass has weakened.

St. Augustine decline is typically spread by mowing equipment, edgers and other tools. St. Augustinegrass affected by SAD is also slower than healthy grass to recover. In the springtime following an unusually cold winter, much of the diseased St. Augustinegrass does not recover.

If your St. Augustine turf has been infected with St. Augustine decline, you have options. Solutions Pest and Lawn can give you the products and lawn care know-how to overcome this virus properly.

Since St. Augustine Decline is a viral disease that has no cure, the best you can do when you have it is to keep it from spreading and let nature run its course, hoping that rainfall will return to eliminate the problem. However if you just want the disease gone immediately you can cut the affected areas or engage in some sort of manual or mechanical removal. However for large severe outbreaks of St. Augustine Decline, it may be best to spray a fungicide to keep it from spreading across your lawn with its ugliness. We have provided three basic steps for you to follow below to properly treat this fungus.

Step 1: Inspect and correctly identify if the mold you are seeing is indeed  St. Augustine Decline. While slime mold can be quite apparent to diagnose there may be cases where you may get the disease confused a more harmful disease. Identifying the growth correctly will help you in selecting the proper fungicide and help you in your treatment approach. If you are not entirely sure whether or not it is slime mold, we here at Solutions can help. Send us a photo of what you see to identification@solutionsstores.com and we will respond back quickly with the proper ID of the disease as well as give you recommendations on fungicides specially design to treat St. Augustine Decline.


Step 2: Once the disease is properly ID’d as St. Augustine Decline, you can move on to treatment. We have a variety of different fungicides which can effectively treat and remove slime mold. Choose a fungicide we have listed below and mix using a hand-pump sprayer. Spray the affected areas immediately going in accordance with the instructions found on the fungicide label. You may have to re-apply fungicides a few times to provide continuous control of St. Augustine decline.


Step Three: Once the St. Augustine decline has been taken care of, you can carry out a few maintenance tasks to ensure the disease doesn’t return. Giving your turf adequate sunlight by removing shady areas is a good start. Also reducing the amount of watering you are doing to ease the moisture and let the soil dry out can also be helpful. Overall just paying a bit more attention to your lawn's needs will go a long way in controlling St. Augustine decline and making sure it doesn’t re-emerge.

 

Learn More About St. Augustine Decline

St. Augustine Decline (also known commonly as Take All Patch) is becoming more and more of a problem in central Texas, Louisiana and across the Gulf Coast region as we rely more and more on our city water to irrigate our lawns and landscapes.

 

What St. Augustine Decline is is a viral disease which affects St. Augustine Grasses. However, despite the name, it can also be formed on other grass types such as bermudagrass, zoysia grass and centipede grass.

 

The lawn disease was first discovered on St. Augustine grass in 1991 and since then has been appearing more frequently in hotter regions in the south where there is a drought.

 

Signs of St. Augustine Decline

St. Augustine Decline can be a disease that property owners may misdiagnose due to the disease looking similar to a nutrient deficiency or lawn insect issue. So what some DIYers will do is start to fertilize or lay out insecticide in hopes to reduce the problem, not knowing the entire time that what they are dealing with is actually a viral issue.

 

If you try to treat the symptoms and they don’t happen to disappear or they get worse, then it may very likely be St. Augustine Decline. Some of the clear symptoms of the virus include:

 

  • Splotchy, yellow colored blades. The appearance of yellow is often due to stress and is called chlorosis, which is brought on by the disease. Chlorosis can occur by a number of other things such as turf insect damage or zinc deficiency, but if you find yellow over the entirety of the lawn, this is a clear characteristic of St. Augustine Decline.

  • Lawn becomes weak and may start to thin in circular or irregular looking patches. Grass blades may look faded and ill, signaling a problem.

  • Stolon growth becomes stunted or stops. Stolons are offshoots of growth from an individual blade. Stolon growth contributes to a thick, bountiful appearance. St. Augustine Decline can also result in stolons being very easily lifted or pulled away from the soil due to the root system being weakened and affected by the virus. This may be mistaken for white grub damage due to the similarity in symptoms.



Have A Lawn Issue That Isn’t St. Augustine Decline ? Check out Our Lawn Care Main Category!

 

Cause of St. Augustine Decline

As the temperature goes up and the rainfall seems to be a little bit less every year, landowners usually have to irrigate more to subsidize the lack of rain. The problem is that the water that is being used from the city’s ground water supply (lakes and rivers) is full of lime from the limestone that’s found naturally in those same areas.

 

That lime causes the pH to rise. On the opposite side of that is of course rainfall. Rainfall is really acidic in nature (we’re sure you’ve heard of acid rain) and thus the two together normally keep the pH at a relatively medium level (usually around 7). The problem arise when there is a dry year or a drought season where you have to subsidize the rainfall with watering your lawn and that causes the pH to rise.

 

What this plays into with St. Augustine Decline is that the disease can’t survive at a pH below 6.7. So when we have a lot of rainfall what happens? The pH falls. When there isn’t a lot of rainfall and you have to water your lawn, the pH rises. So what happens is that the Take All Patch or St. Augustine Decline thrives when the pH is higher and you will start to see it spread.

 

Have Some Grassy Weeds You Want Gone? View Our Grassy Weed Control Section

 

St. Augustine Decline Life Cycle

The St. Augustine decline pathogen overwinters as dormant mycelia in living and dead plant tissues. The fungus will then form dark brown to black ectotrophic runner hyphae on roots and stems of host plants.  St. Augustine infection occurs when the fungus penetrates underground plant tissues and spreads to nearby plants by growing along roots and lateral shoots.

 

St Augustine decline can become most active in cool wet periods, but symptoms are more obvious during drier conditions in early to midsummer. St. Augustine decline is mainly a root and crown attacking fungus and is soil and seed borne. The disease is can become a major problem in 3rd and 5th years after planting and then declines.

 

Like most diseases such as brown patch or leaf spot, St. Augustine decline can be spread by foot traffic, mowers and various other means of movement. If you have a small area where it is established, it is most likely going to spread if you don’t intervene.

 

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

 

Inspecting Your Lawn For St. Augustine Decline

St. Augustine Decline also goes by Take-All Patch because it tends to remove the grass from your lawn so you end up with a bare spot; it takes everything so all you’re left with is just dirt.

 

Generally you’ll find it in the shady areas of the lawn like most lawn disease problems. Hardly ever will you find this disease in full sun. When inspecting for St. Augustine Decline on your lawn you need to examine the stolons.

 

This disease causes a rotting of the stolon itself, the actual runner of the grass. If you pull out a runner you will see that it browns or almost blackens lengthwise down the stolon. If you start to pull the stolon up from the dirt, you’ll see that the roots themselves are stunted, shortened and they’re discolored as well, looking brown to black.

 

Normally, the roots should be a creamy white color and pulling the plant out from the root would be a bit difficult. A lawn infected with the disease, the plants could be pulled out easily with just a slight tug.

 

When diagnosing the problem it’s most effective to start at the edge of the problem right beside the healthy grass. Go to the edges and try to pull up some turf grass and examine the roots themselves and check the colors as well as the stolon. Compare the diseased plants that have been pulled out to a healthy plant.

 

Control Options For St. Augustine Decline

St. Augustine Decline can be a little difficult to treat in that most fungicides don’t work on it. A lot of fungicides are sold for treatment of St. Augustine decline but that doesn’t necessarily mean that they work. One of the more common treatments that actually works quite well is peat moss. Peat moss has a very low pH (2 or 3).

 

Spread the peat moss over the affected area and use about a bale (which could treat about 500-700 sq feet). Make sure not to cover the blades of any healthy grass when spreading peat moss. The way it works is that as the peat moss decomposes in the soil it helps to hold the pH down so the disease doesn’t spread or thrive more.

 

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

 

The best fungicide options for St. Augustine Decline Which we recommend include products which contain the active ingredient Thiophanate (Quali-Pro TM 85 WDG Fungicide) and Azoxystrobin (Heritage Fungicide) You could also try products which contain propiconazole (Patch Pro Fungicide and Propiconazole 14.3 Fungicide) Make sure to check the label for proper usage instructions and take note that these may or may not do the trick since again there is no clear cut cure for St. Augustine decline at this time but you can go ahead and try one of these fungicides and see if they alleviate the problem.

 

Conclusion

 

To recap, St. Augustine Decline is a viral disease that occurs in the shade and where you will see the runners appearing black or brown and roots will be stunted and will release very easily from the soil. It is a difficult lawn disease to eliminate even with the help of fungicides but by combining cultural control measures with possible fungicides you may be able to control the issue.

 

Additional Resources:

 

[PDF]St. Augustine Decline (SAD) - LSU AgCenter

 

Ask Extension - St Augustine Grass (Horticulture & Home Gardening)

 

St. Augustine Decline | Archives | Aggie Horticulture



 



 

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