The virus killed St. Augustine grass in Florida
You may be familiar with common pests and pathogens that harm St. Augustine turfgrass lawns on an annual basis, such as universal root rot (Gaeumannomyces graminis var. Graminis), rhizoctonia solani, and southern chinch bug (Blissus). insularis) and tropical grass webworms (Herpetogramma phaeopteralis). Now, not only do we have to deal with these pests, but we also have to beware that there is a virus attacking our most common types of grass as well.
Lethal viral necrosis (LVN) is a deadly form of sugarcane mosaic virus (SCMV) that can kill St. Augustine grass.
The virus has been reported in other grass species, but the susceptibility of other grass species is currently unknown. It is currently only a concern in St. Augustine turf. Floratam, a commonly used variety of St. Augustine grass, has been reported as the least resistant variety to this disease.
How to stop the spread of deadly viral necrosis
Once turf is infected there is no cure. Pesticides, fertilizers and other inputs are ineffective and cannot stop the spread or progression of the disease. The only way to control is to limit the spread of the virus by sterilizing equipment and keeping infected materials in infected locations.
To sterilize equipment, remove plant material from equipment before moving to another garden, and then spray parts of equipment and workers’ shoes that have the potential to transfer plant sap with diluted bleach, quaternary ammonia (Green-Shield), alcohol, or other materials. Other sterilization. agent according to the instructions.
If you mow your lawn yourself, mow the healthy areas of your lawn before the infected areas and disinfect them after mowing. If you are mowing many lawns where the virus is known to occur, mow healthy-looking lawns before those showing mosaic symptoms, and avoid mowing lawns with mosaic symptoms when the grass canopy is wet (avoid mowing when dew, irrigation, or rainfall persist ). Avoid purchasing infected plant material. If the grass is infected and dies, replace the dead grass with non-Floratam varieties that are more resistant to this pathogen. Avoid additional stressors on your lawn by following the best management practices listed here: edis.ifas.ufl.edu/publication/LH010. For more information about SCMV in St. Augustine grass, go to: edis.ifas.ufl.edu/publication/PP313. To confirm the presence of the virus and other diseases, send a sample to the UF/IFAS Plant Diagnostic Center. Assembly and application instructions can be found on their website: plantpath.ifas.ufl.edu/extension/plant-diagnostic-center.
The deadly form of sugarcane mosaic virus now found in North Florida
Sugarcane mosaic virus (SCMV), also called mosaic disease, has been present in Florida since the 1960s. The virus was first found in sugarcane. This disease affects different types of grass.
Symptoms of the disease appear as yellow-green striped patterns on leaf blades. Mosaic patterns can vary depending on the severity of the infestation and the types of plants being attacked.
Prior to 2013, there were no reports of St. Augustine grass dying from the virus, and only the striped appearance was reported. Then in 2013, new symptoms of plant death and necrosis were reported. This development was called lethal viral necrosis (LVN).
Previously this was only a problem in South Florida, but now positive samples have been identified in North Florida. Symptoms are most noticeable in the fall and winter months when the grass begins to go dormant. Certain nutrient deficiencies, such as nitrogen, can cause a yellow appearance similar to grass. However, in the case of nitrogen deficiency, the yellow zone follows the vein in the line, while SCMV causes discontinuous lines in a mosaic-like pattern.
SCMV can be spread by mechanical vectors such as lawn mowers, trimmers, and other lawn equipment. The virus is also spread by insect vectors, but their importance is currently unknown. Anything that can transfer grass clippings or sap containing the virus from grass to lawn can be a vector. Stop the spread.
George Richardson is a commercial horticultural extension agent with the UF/IFAS Extension in Duval County.