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Southern Blight Fungus

Southern Blight Fungus Facts

Southern Blight Lawn Care

There are many microorganisms in your lawn that are beneficial, aiding in thatch decomposition. However, there are also a few harmful organisms that are parasitic forms of plant life called fungi. Fungi live in soil, thatch and dead leaves within the lawn all year long. These fungi feed on the grass by drawing nutrients from the plant and destroying the plant cells. Diseases spread, in the form of spores, throughout your lawn by wind, air, water, and traffic. The disease may re-appear from year to year if certain conditions are favorable. As a general rule, areas that have been prone to disease problems in the past will at some time, if not yearly, have the same problems again. Southern Blight Fungus attacks primarily bentgrass, bluegrass, fescues, and ryegrass. Southern Blight first appears during hot weather forming circular patterns a foot in diameter that can be found in some cases as large as 9 feet in diameter. Sometimes only partial circles or crescent-shaped areas are affected with the disease with some plants remaining alive in the center. Affected turf has a reddish-brown coloration, turning brown as it dies and white mycelium may be found. Light to dark brown sclerotia, which are tiny, hard, resting bodies are usually present on the outer edge of the ring develop at the base of the stems of the turf grass which can help in diagnosing this disease.

Conditions Favoring the Disease

Southern Blight Fungus survives as sclerotia during the fall, winter and spring on dead plants and in the thatch. The sclerotia will germinate during times of hot weather usually above 75 degrees Fahrenheit and start feeding on organic matter and then spreads to live plants. If dry conditions occur followed by excessive moisture and high temperatures of 85 to 95*F this is conducive to high levels of sclerotia germination. Cold weather will kill the disease thus limiting it to warmer regions.


Well fertilized turf rarely has problems with Southern Blight and Weed Man's exclusive brand of slow-release nitrogen feeds the plant as it needs it through the root. This will help ensure healthy turf without leading to problems later on. Watering properly is extremely important in this turf damaging disease. Avoid watering at night during hot humid weather which extends the leaf wetness period and can lead to a greater chance of Southern Blight. Proper raking and aerating will also help in preventing this disease by limiting the amount of thatch in the lawn. Always follow recommended cutting heights for your turf and keep a sharp mower blade to allow leaf blades to heal quickly.

Your Local Weed Man Dealer Can Help

Your locally owned and operated Weed Man dealer is here to help. Weed Man's turf specialists can recognize Southern Blight fungus and make recommendations to help your lawn. Weed Man's specially blended slow release fertilizer applied at the right time is the first step in preventing Southern Blight fungus. Weed Man's fertilizer helps create healthy turf by slowly feeding the lawn as it needs it encouraging deep rooting systems. Your local Weed Man dealer will also be able to advise you on any other treatments or cultural practices that may be necessary to help your turf remain healthy and vigorous.