Mosaic Disease: A Threat to Floratam Lawns
Mosaic Disease of Floratam St. Augustinegrass is a major new viral threat causing death of this popular turf variety. This winter, it is being increasingly noticed due to the colder weather inducing leaf blade symptoms.
Floratam variety has been one of the better St. Augustinegrass varieties over the years, and probably comprises 90% or more of the St. Augustinegrass lawns in Florida. Losses due to the mosaic disease (actually 2 viruses combined) have been severe, especially in the Boynton Beach and Wellington, Florida areas, and the spread continues.
The mosaic can also infect, but does not kill other St. Augustinegrass varieties, Bermudagrass, Bahiagrass, Paspalum and Crabgrass. Zoysiagrass is not affected.
The viruses are mainly spread in the moist sap from freshly cut lawns on the wheels of mowers, blades, mower decks, and probably line trimmers. Aphids may occasionally spread mosaic disease. Floratam St. Augustinegrass weakened by the mosaic disease is much more susceptible to fungal problems like Take-all Root Rot and weeds.
What Can You Do?
Fungicides and other pesticides are ineffective against this mosaic. No “vaccine” exists.
Replace dead or dying Floratam St. Augustinegrass with Bitterblue or Palmetto St. Augustinegrass varieties, or other resistant turfgrasses like Zoysiagrass, Bermudagrass or Bahiagrass. Additional St. Augustinegrass variety recommendations are likely as UF/IFAS research continues.
After mowing infected lawns, blow grass debris off equipment and wheels. Then spray equipment until wet with one of the following disinfectants and allow to dry before using equipment on other lawns.
- 2% solution of DuPont Virkon S disinfectant
- 9 parts water to 1 part Household Bleach solution (5.25% sodium hypochlorite) Warning: bleach causes steel to rust
When possible, avoid mowing wet lawns. Leaving clippings on infected lawns will not increase the spread of mosaic, nor will the use of reclaimed irrigation water.
For more information, see the link above, and the UF publication Mosaic Disease of St. Augustinegrass Caused by Sugarcane Mosaic Virus.