If your lawn has been diagnosed with Lethal Viral Necrosis (LVN) — sometimes called mosaic virus — you’re not alone. This disease has become increasingly common across South Florida, especially in lawns planted with Floratam St. Augustinegrass.
Below, we’ll explain what LVN is, why it happens, and what you can do to manage it.
What Is Lethal Viral Necrosis?
Lethal Viral Necrosis is caused by the Sugarcane Mosaic Virus (SCMV) — a plant virus that originally affected sugarcane but eventually spread to certain turfgrasses.
The virus was first identified in Florida lawns in 2014, and since then it has caused major losses in neighborhoods planted with Floratam St. Augustinegrass, one of the state’s most popular sod varieties.
When the virus infects Floratam, it slowly damages the grass until it can no longer recover — leading to large, thinning patches and eventual turf death within a few years.
The Grass Most Affected
LVN affects only Floratam St. Augustinegrass.
Other types of St. Augustine, like Palmetto or CitraBlue, might show mild mosaic patterns but they don’t die from the virus. Unfortunately, Floratam is highly susceptible, meaning once the virus is present, the lawn will continue to decline no matter what products or treatments are applied.
Recognizing the Symptoms
You may notice:
- Irregular yellow or light-green streaks on grass blades (a “mosaic” look)
- Thinning or patchy turf
- Dead areas that spread over time
Once these patches appear, the disease continues to move through the lawn until all Floratam is gone.
There’s No Cure or Prevention
There’s no chemical, fertilizer, or treatment that can cure or prevent LVN. Fungicides and insecticides will not stop the virus because it lives inside the plant tissue, not in the soil.
Even with perfect lawn care, Floratam grass cannot recover from infection. The only permanent solution is to replace the infected turf with a resistant variety.
How LVN Spreads
The virus spreads through contact with infected plant sap, usually by:
- Lawn mowers, trimmers, and edgers
- Shared tools or equipment
- Sod or plugs taken from infected lawns
- Occasionally by insects like aphids
It’s important to note that the virus does not live in soil or water, and once grass clippings have dried, the virus becomes inactive.
How to Limit Further Spread
If your lawn is infected, you can still help prevent it from spreading to healthy areas:
- Disinfect all lawn equipment after use (a 10% bleach solution or a disinfectant like Virkon S works well).
- Mow healthy lawns first, infected lawns last.
- Avoid mowing wet grass — moisture helps transfer the virus through sap.
- Throw away infected clippings instead of using them as compost or mulch.
- Only purchase sod from reputable farms that confirm it’s free of LVN.
These steps won’t cure the disease, but they can slow its progress and help protect nearby lawns.
The Long-Term Solution: Replacing Floratam
Once LVN is confirmed, the most effective and lasting solution is to remove and replace the infected Floratam with a more resistant grass type.
Recommended options include:
- Palmetto St. Augustine – similar in look to Floratam but more tolerant and not known to die from LVN.
- CitraBlue St. Augustine – a newer variety with a rich blue-green color and strong resistance.
- Zoysiagrass – an entirely different species that doesn’t host the virus at all.
To replace the turf:
- Remove all existing Floratam sod and roots.
- Prepare the soil by leveling and amending as needed.
- Lay the new sod and follow a solid watering and mowing schedule.
- Keep equipment clean to avoid reintroducing the virus.
In Summary
Lethal Viral Necrosis only affects Floratam St. Augustinegrass — and once it appears, it cannot be reversed. While that’s discouraging news, replacing the turf with a resistant variety gives you a long-term solution and a healthy lawn again.
If you need help removing infected grass or choosing a replacement, our team can guide you through every step of the process — from identifying LVN to selecting the right sod for your property.