Lethal lawn virus spreads in Florida

Photo: Phil Harmon

Parts of Florida are experiencing an outbreak on lawns. A new virus is killing Floratam, a variety of St. Augustinegrass in central and South Florida. The virus has spread from Palm Beach County to Naples, and another outbreak appeared in St. Petersburg.

Although Floratam is used in other states, the virus is currently exclusive to Florida, says Phil Harmon, a professor and extension specialist at the University of Florida.

The culprit is the lethal viral necrosis of Floratam, a disease associated with two viruses including the mosaic virus. “What we’ve found is that the two viruses have to be in Floratam grass at the same time for the new disease to occur,” he says.

Floratam lawns will die in three to five years once infected with lethal viral necrosis. Symptoms start in autumn and progress through the winter. The grass yellows, gets thin and weeds begin to take over by spring.

There is no cure once the disease takes hold, and the lawn will eventually need to be resodded.

So, the goal is to prevent the virus from spreading between properties in the first place. “We recommend sanitation and the cleaning of mowing equipment, trimmers and personnel shoes to prevent moving the virus from lawn to lawn,” Harmon says.

The disease was discovered, in part, from complaints of fungicide product failure. Some fungicide company representatives were getting reports that their products weren’t working. But, fungicides don’t work on viral diseases, Harmon explains.

“Some of these lawns were being exposed to five or six fungicides, but they were dying anyway,” he says. “Partly because of misdiagnosis and also because we didn’t know this viral disease was out there.”

There are a lot of reasons why lawns can die, and this is a very specific reason on a very specific variety of grass, Harmon says. So, correct diagnosis is important to prevent unnecessary fungicides from being used.

Harmon recommends using a diagnostic service at a nearby university. “Identification is a good first step in any effective and efficient management strategy,” he says. “Determine what the enemy is and how to best and most efficiently address it.”