St. Augustine Decline (SAD Virus)
St. Augustine Decline (SAD) is a viral disease caused by Panicum Mosaic Virus. Symptoms: mottled, stippled yellow-green pattern on blades (not uniform yellowing), stunted growth, and gradual thinning over months to years. There is NO chemical cure — fungicides and fertilizers will not help. Do not confuse SAD with chinch bug damage (which has distinct expanding brown patches) or iron chlorosis (which has yellow blades with green veins). The only solution is to remove infected turf and replace with a SAD-resistant cultivar. Floratam was originally bred for SAD resistance and remains the best option. Raleigh and Palmetto also show good resistance. SAD spreads through infected sod, plugs, and mowing equipment — sanitize mower blades with 10% bleach between properties.
Frequently Asked Questions
What is St. Augustine Decline?
SAD is caused by Panicum Mosaic Virus. It creates a mottled, stippled yellow pattern on leaf blades — different from nutrient deficiency or chinch bug damage. There is no chemical cure.
How does SAD spread?
SAD spreads through infected sod, contaminated mowing equipment, and mechanical transfer. Always clean mower blades between properties. Buy sod from reputable sources.
What should I do if my lawn has SAD?
Remove infected grass and replace with a SAD-resistant cultivar like Floratam. Sanitize all equipment that touched infected turf. SAD-resistant varieties have made this disease much less common.
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