Plants affected with fungal root rots may be stunted, wilted, look generally unhealthy, and eventually die. Discolored, decayed roots are sure symptoms of root rot diseases. Poor drainage, standing water, improperly constructed landscape beds, planting infected plants, and excessive irrigation favor phytophthora and/or pythium root rots.

Learn more about the different root rot issues in UT Publication IPM QuickFacts Series W289 by clicking on the links below:

Black Root Rot

Phytophthora Root Rot

Southern blight usually occurs in gardens, perennial borders, and nurseries during hot weather, near mid-summer. Symptoms include wilting and leaf scorch followed by plant death. Signs of disease include white mycelium on the stem of infected plants and tan to reddish-brown round, spherical resting structures of the fungus (sclerotia) on the stem and soil surface.

Sclerotinia crown rot usually appears during mid-spring to early summer when conditions are cool and moist. Affected plants usually wilt and die. White mycelium may be visible on stems near the soil surface. Black, oblong sclerotia may be present on the outer surface of woody plants or in the stem pith of herbaceous plants. Diseased stems should be split lengthwise and examined for signs of sclerotia.

Rhizoctonia stem rot/damping off is often the cause of stem rot and death of seedling plants. Seedling annual or perennial flowers or woody ornamentals may be killed by this fungus after it attacks the stem near the soil surface. Diseased seedlings often fall over and die. In the field, the fungus may move short distances down the row, killing several adjacent plants. In propagation beds or flats, diseased plants may be killed in circular areas as the fungus moves outward.

Check root healthy prior to purchasing plants in containers. Avoid planting susceptible plants into heavy, poorly drained soils. Avoid soil contamination of new pots, flats, and soil-less media. Place container plants on gravel or ground cloth.

For southern blight and Sclerotinia crown rot, remove infested plants plus the soil near the stem to remove sclerotia.

For chemical control recommendations, consult the Insect and Plant Disease Control Manual, UT Extension Publication 1690, found here. Please contact your local Extension office for specific pesticide recommendations.