University of Florida

Southern Blight

Fungus

Sclerotium rolfsii

Infects

Lower stem, roots, and fruit.

Symptoms

Root and lower stem decay at soil line causing plant wilt and death; fruit touching soil or infected tissue develop yellow, slightly sunken spots that rupture the epidermis when 1/2 - 3/4 in. diameter producing a deep, rapid mushy rot; silky white fungal strands grow fan-like over the external stem, adjacent soil and fruit during moist periods; small mustard seed-sized sclerotia form on the mycelium, first white then tan when mature.

Pathogen Spread

Soilborne, machinery or water-moved infested soil, survives on numerous weed and crop hosts.

Favorable Conditions

Wet periods of high temperatures (85-95 F.). Rarely a problem in area 1 (Appendix 9). Can be a major problem in area 5.

Southern Blight Pictures

southern blight
Image # 106.
Southern blight
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rapid plant decline with white fungal mycelium evident at the crown during moist weather.

southern blight
Image # 107.
Southern blight-
Immature sclerotia on fruit. Mature sclerotia are of similar size, but are salmon pink in color.