A plant disease linked to sugarcane that had largely vanished 40  years ago has suddenly reappeared, becoming the first virus in the state  to attack South Florida's manicured lawns.
Scientists don't know  why the disease suddenly morphed and began spreading in Palm Beach and  Pinellas counties. And so far they have no tools to stop it, other than  cleaning lawn equipment or replacing sod with more resilient varieties,  said Phil Harmon, a plant pathologist with the University of Florida's  Institute of Food and Agricultural Sciences.
At this point we don't know what the outcome will be, so were being proactive and trying to get the word out, Harmon said.
Called 
Sugarcane Mosaic Virus,  the disease first appeared in sugarcane and sod growing near cane  fields in the 1960s, Harmon said. To control the disease, growers  developed resistant sugarcane. The virus virtually disappeared, only  appearing sporadically in grass near cane fields and only causing  yellowing.
But in 2013 something changed, he said. Lawns with the  popular Floratam St. Augustine grass, the most widely used in  landscaping, started dying. The virus adapted somewhere to kill this variety of turf grass, Harmon said.
When  the grass started dying at a Boynton Beach subdivision last fall, Greg  Russell, a field supervisor with Hometown Pest Control, assumed a fungus  was making it sick and applied a fungicide. The treatment didn't work.  Over the spring and summer, the grass bounced back on its own, Russell  said. This fall, it started dying again. And the dead patches spread.  Russell tried four different treatments before he gave up in frustration  and called Harmon's office for help.
A quick examination confirmed the cause: Mosaic virus. The virus has now spread to about 150 lawns, Russell said.
No matter what we did to it, nothing changed, he said. It's tough for  people to hear that there's nothing we can do. Just wait it out. Scientists  do not know what changed in the virus to cause it to spread, Harmon  said. And while it infects other grasses, Floratam has been hit hardest,  nearly always dying when it's infected. The grass can regrow, but it  will carry the virus and likely die in September or October, when  conditions are right for symptoms to resurface.
In addition to  sugarcane, the disease has sickened corn, sorghum and other grasses,  Harmon said. It is usually transmitted by lawn equipment: the sap from  infected grass can stick to mowers and weed-eaters and wind up in  healthy lawns.
With no chemical treatment available, Harmon said  the best defense is a good offense: clean equipment with Lysol or a  commercial ammonia or consider planting another kind of grass. Zoysia  grass doesn't catch the virus, but has its own problems: the grass is an  invasive that can spread and crowd out all other plants. The Palmetto  and Bitterblue types are more resistant St. Augustine grasses, but also  have their own issues, Harmon said. Bitterblue is susceptible to chinch  bugs and Palmetto doesn't do well in shade.
To try to find a cure  and better document the disease, Harmon said anyone who suspects the  disease has infected their grass should notify UF's 
plant diagnostic center or logon to its 
Facebook page, RapidTurfgrassDiagnosticService, to post a picture.
Scientists  hope to determine if the disease is more widespread than we think,  Harmon said. Our concern is that it could potentially spread like it  did in the ?0s  We don't know what's going to happen next, but we'd  like to get a better handle on where it is by getting people to send  samples.