Southern blight is a plant disease that is active now in hot summer weather. It is caused by a fungus called Sclerotium rolfsii. This fungus has a wide host range including woody plants, vegetables and herbs, and ornamental perennials such as coneflower, peony, and hosta.
Signs and Symptoms of Southern Blight
- The first symptoms seen are wilting and collapse of individual stems or entire plants.
- Close inspection of the stem at the soil line reveals white mycelium (strands of fungus growing on the stem and/or soil surface), and small, white or tan spherical sclerotia that resemble mustard seeds.
- Roots of infected plants are unaffected. Decay of the stem at the soil line is common during hot, humid weather.
How to Manage Southern Blight
- The cornerstone for control of southern blight is clean-up of diseased plants in the garden.
- Wilted and blighted plants and plant parts should be promptly removed from the garden.
- Do not compost material killed by southern blight because the resting spores (sclerotia) of these fungi may survive the composting process.
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By Dave Clement, Principal Agent, University of Maryland Extension, Home & Garden Information Center