St Augustine Grass
St. Augustine Grass Decline
St. Augustine Grass Decline
St. Augustine Decline (SAD) (Also called Take-all Patch).
A virus causes it, which produces the following:
- Circular patches .5 to 3 ft. in diameter
- Initially yellowish; Gradually turning brown and thinning
- Darkened roots
- Chlorotic leaf blades may develop next to green shoots at margins of diseased area
- Roots brown without feeder roots and root hairs.
St. Augustine Decline (SAD) is a virus causing a chlorotic mottling or stippling of St. Augustine grass leaves. St. Augustine grass and Centipede grass are the only turf grasses that the virus affects.
In the early stages of infection, St. Augustine grass leaves show a chlorotic mottling or stippling. As the mottling progresses, leaves develop a chlorotic appearance. Usually 3 or more years after the early symptoms are observed St. Augustine grass becomes weakened to the extent that Bermuda grass invades the lawn. Grass infected with SAD and growing under shade or other stress conditions will begin to thin out and be replaced by weeds.
St. Augustine grass infected with SAD is also slower than healthy grass to recover. In the spring following an unusually cold winter, much of the diseased St. Augustine grass does not recover.
Lawns infected with SAD will respond to organic fertilization, but the symptoms remain. Early fall and late spring applications of complete organic fertilizer and summer applications of liquid lawn iron will help maintain good color of SAD infected lawns.
Early stages of SAD are often confused with iron chlorosis. Leaves showing chlorosis caused by iron deficiency are either uniformly yellow or show characteristic yellow stripes parallel to the mid-vein of the leaf. Iron chlorosis also appears first in the new, or young leaves; whereas SAD produces the mottling in both young and older leaves. Iron chlorosis is readily corrected by a foliar application of liquid lawn iron. Note: high soil pH (above 7.2) will bind iron to the soil, making it unusable. Lowering soil pH could free up iron already present in the soil.
The SAD virus, like all viruses, is a microscopic particle found inside the cells of St. Augustine grass. Inside the plant cell, the virus reproduces and spreads to other cells throughout the plant. As more and more cells become infected with the virus, the vigor of the plant is reduced, rendering it more vulnerable to other diseases and environmental stresses.
Control
The SAD virus, mechanically transmitted by mowing equipment, edgers and other tools, spreads quickly. Mowing companies that mow several lawns with the same equipment can transmit the virus from an infected lawn to a healthy lawn. Cleaning the mowing equipment with steam or a 10% Clorox solution will help prevent the spread of the virus. However, the best control for the virus is to introduce resistant varieties of St. Augustine grass into the lawn. Presently, Floratam, Floralawn, Raleigh and Seville are SAD-resistant varieties of St. Augustine grass. Simply plug the resistant variety into the existing lawn on 2- or 3-foot centers. The resistant grass will crowd out the diseased grass over a period of a year or more.
For more tips, techniques and organic products, visit our website,
Steve
About the Author
Age: 62, There’s a lot of experience in these gray hairs!
Education: Master of Science in Quality Management, Quality Control
Status: Married 38 years, 4 children, 10 grandkids
Company: The Organic lawn Care Store – http://www.theorganiclawncarestore.com/
St. Augustine Grass Care – Spring 2010.mov
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