St. Augustine Decline Control: How To Get Rid of St. Augustine Decline

This page is a general guide to controlling St. Augustine Decline. By following this guide and using the recommended products, you will control the disease known as St. Augustine Decline. We guarantee 100% control of St. Augustine Decline.

St. Augustinegrass is one of the most popular turfgrasses 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, if a lawn owner doesn't keep up with routine grass care, it could be subject to rot and disease, such as St. Augustine decline, also known by the fitting acronym SAD.

St. Augustine Decline (SAD) is a viral disease that causes St. Augustine Grass blades to have speckles of discoloration. The virus is mainly found on landscapes in Texas, but instances of the disease have been reported in Louisiana and Arkansas.

Mowing equipment, edgers, and other tools typically spread St. Augustine's decline. St. Augustine grass affected by SAD recovers slower than healthy grass. In the springtime following frigid winters, much of the diseased St. Augustinegrass does not recover.

If your St. Augustine turf has been infected with St. Augustine's decline, you have options for control. Follow the DIY treatment guide below to learn what products and techniques to overcome this virus properly.

Identification

While St. Augustine's Decline can be pretty apparent when diagnosing, there may be cases where you may get the disease confused with something else. Identifying the disease correctly will help you select the proper fungicide and help you in your treatment approach. Here are some identifying traits to observe for St. Augustine Decline:

• When turf becomes infected with Saint Augustine Decline, grass blades will start to yellow. This may look similar to when grass has an iron deficiency, but there is a way to tell the two conditions apart.
• Saint Augustine Decline resembles mottled yellow splotches on younger or older grass blades. The die-back of turf can take up to three years after the first initial symptoms appear. 
• If your grass has an iron deficiency, usually only younger grass blades will appear uniformly yellow or have yellow stripes parallel to the blade’s mid-vein.

Use the description and image above to help you identify the St. Augustine decline on your lawn. If you are not sure if you have SAD, contact us, and we will help you properly identify the disease and suggest the best treatment option.

Inspection

Once you confirm that you are dealing with St. Augustine decline, you can move on to inspection. During this phase, you will locate all areas where St. Augustine decline is developing and observe the conditions allowing it to thrive. This information will help you know where to focus your fungicide applications. 

Where to Inspect

St. Augustine decline often appears year-round in St. Augustinegrass in the Gulf Coast portion of the United States of America, including Texas, Louisiana, and Arkansas. 

It's also known to affect Centipedegrass as Centipede Mosaic. 

What To Look For

When diagnosing St. Augustine Decline, it is 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 turfgrass. Examine the roots themselves, check the colors, and check the stolon. Compare the diseased plants that have been pulled out to a healthy plant.

SAD causes rotting of the stolon, 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 will see that the roots themselves are stunted, shortened, and discolored, looking brownish or black.

Usually, the roots should be a creamy white color, and pulling the plant out from the root would be a bit difficult. However, on a lawn infected with the disease, the plants could be pulled out easily with just a slight tug, which can be mistaken for turf damage from grubs.

Be mindful that symptoms from St. Augustine's decline can take up to 3 years to appear, so we recommend treatment and inspection as soon as possible. 

Treatment

Unfortunately, if you have St. Augustine Decline, no chemical method of control is available to cure an infected lawn of the disease or prevent its spread.

Most St. Augustine lawns recover from the disease and will outgrow it, while others may be slow to recover from the virus.

What can be done, however, are cultural practices to reduce the disease's visual symptoms by keeping up with regular cultural lawn care practices and maintaining your turf's health. 

Step 1: Clean Mowing and Other Application Equipment

The virus that causes St. Augustine decline is usually transmitted by the sap from a diseased plant to a healthy plant. Typically, this happens when mowing or other application equipment from one part of your property to another. 

Let your mower cool down and ensure it is turned off before cleaning it. 

You can begin cleaning when it is fully turned off, and all parts have stopped moving. 

Tilt or lift the mower to its side with the underside fully exposed. On some mower types, you may have to remove the deck to access the bottom portion with the blades.

Remove the mower blades to clean the underside portion thoroughly. 

Use a brush or leaf blower to remove dirt, grass, and other debris that has built up on the mower's underside and top. 

When all larger debris has been removed, gently wipe any remaining debris with a rag. 

During cleaning, ensure you wear protective eyewear, such as safety glasses, to prevent debris from flying into your face and eyes. 

Disinfection of all other application equipment with a disinfectant would be best. 

Depending on the equipment, you may need to steam clean it or use a 10 percent bleach solution. 

Step 2: Prune and Clear Away Leaf Litter

Trim overgrown shrubbery and tree branches, rake away leaf litter, and pick up debris to reduce the shade cast on your lawn.

Step 3: Modify Watering

Employ a proper watering schedule to provide your lawn with enough water to strengthen its roots, but not so much that it encourages disease.

Most lawns require 1 inch of water every week.

Apply the water all at once in the morning so it has time to seep into the ground without evaporating in the sun.

Prevention

Once the St. Augustine Decline has been cleared off your lawn, keep the disease from returning by implementing regular lawn care maintenance. We suggest some preventative measures to keep St. Augustine Decline from returning.

• Regular fertilization with a slow-release fertilization will help strengthen your St. Augustine turf and fight against future disease activity. Determine how much fertilizer to use by measuring the square footage of the treatment area. Find the square footage by measuring the treatment area's length and width in feet, then multiplying them (length X width = square footage). For the summer season on St. Augustine turf, we suggest using the Solutions Pro Grow Summer Blend 19-4-10 Fertilizer. Apply 5 pounds of Solutions Pro Grow Summer Blend 19-4-10 Fertilizer per 1,000 sq. ft. of turf. For the spring season, use the Solutions 15-5-10 Weed & Feed Fertilizer with Trimec. Keep in mind this fertilizer can cause temporary discoloration in St. Augustinegrass when applied during conditions of adequate moisture, high temperature and high humidity, and over-application. Do not use the Solutions Weed & Feed Fertilizer on 'Floratam' St. Augustinegrass. Apply 3.2 to 4.0 pounds of Solutions 15-5-10 Weed & Feed Fertilizer with Trimec per 1,000 sq. ft. of turf. Mow your lawn 1 to 2 days before application to its average height. Remember to clean it after mowing, though. Then, water the lawn 1 day before Solutions 15-5-10 Weed & Feed treatment. Calibrate the push or broadcast spreader to the proper setting, and then load the appropriate amount of fertilizer. After you are done spreading the granules you will need to water them in order to activate them. Wait for 1 day after application of the Solutions 15-5-10 Weed Fertilizer with Trimec before irrigation can occur. You can water the granules immediately after application using the Solutions Pro Grow Summer Blend.
• Water the lawn deeply and infrequently once a week at a rate of 1 to 1.5 inches of water.
• Trim back trees and reduce shade as much as possible so your St. Augustinegrass gets sufficient sunlight.
• Raise your mowing heights to 3 to 4 inches to assist in the recovery of your grass and strengthen roots.
• After maintaining, cleaning, and fertilizing your lawn, the best way to control Saint Augustine Decline is to introduce a resistant variety of Saint Augustine Grass. You can purchase plugs of disease-resistant grass at a sod or turf specialty store and install them on your lawn. Over a year or more, the resistant grass will grow and crowd out the infected grass, ensuring your lawn stays green as the infected grass dies.

Key Takeaways

What is St. Augustine Decline?

• St. Augustine decline is a viral disease that occurs in the shade. It starts with mottled discoloration of grass blades, which leads to runners appearing black or brown and stunted root growth.

How To Get Rid of St. Augustine Decline

• While there are no chemical methods of controlling St. Augustine Decline, you can plant resistant varieties of St. Augustinegrass to combat the spread of the disease and clean lawn equipment prior to mowing to reduce the chances of transmitting the disease.

Preventing St. Augustine Decline Reemergence

• Once your lawn has been treated, prevent St. Augustine decline from making a return with cultural control practices such as regular fertilization, watering, adjusting mowing practices, and regular cleanup of application equipment used on your lawn to make it less likely that your St. Augustinegrass is infected.