Southern blight causes wilting of cucurbits due to infection on the main stem at the collar region. The pathogen is soil-borne and the disease can be an issue during warm weather seasons.
Wilting symptoms resemble that of Fusarium wilt, but upon careful examination you may find white mycelial growth and mustard like reproductive bodies called sclerotia on the soil and on the stem.
Mycelial growth affected the base of the plant restricted flow of water to the plants and brown matured sclerotia can be seen on the stem and on the top of the soil.
Southern blight affects fruits directly and causes a white mycelial growth on the underside of the fruit leading to severe fruit rot on cucurbits as seen in this case on cantaloupe.
A pumpkin fruit affected by southern blight. Typical symptom in this case is white fungal mycelial mat on the rind area touching the soil, and small white to cream colored sclerotia.
Sclerotia on pumpkin tissue. The sclerotia vary in size, and color from white to brown to dark brown as they age and can survive harsh winter conditions in soil and protects the fungus.