By Jim Stack, former UNL Extension Plant Pathologist and current Kansas State University Extension Plant Pathologist
Pathogen
Ramulispora sorghi (Ell. & Ev.) L. S. Olive & Lefebvre. Fungal structures: conidia produced from a sporodochium and sclerotia. Sooty Stripe is common throughout the sorghum producing areas of the USA occurring every year to varying degrees. Sooty Stripe was severe in several southern Nebraska counties (from Red Willow to Pawnee as far north as highway 6) in 1997 and 1998. In 1998 a double epidemic of Sooty Stripe and Zonate Leaf Spot occurred in many fields. The pathogen survives as sclerotia in plant residue and to some extent free in the soil. The Sooty Stripe pathogen also infects other Sorghum species that may serve as a reservoir of inoculum.
| Conidia | Sporodochium |
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| Sclerotia | |
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Disease Symptoms
Sorghum hybrids vary in susceptibility to Sooty Stripe. The first visible symptoms are the appearance of small non-diagnostic lesions on the lower leaves. These lesions elongate and form the typical diagnostic Sooty Stripe lesions having pronounced reddish-brown lesion margins (on most hybrids) with yellow halos. Lesions may expand and run together, resulting in serious leaf blight. Within the center of mature lesions, rows of very small black bodies form; these black sclerotia give the lesion a "sooty" appearance and can be rubbed from the surface leaving a smudge on your finger. When the weather is favorable the disease progresses up the plant and lesions may occur on all leaves of the plant.
| Sooty stripe lesion | Leaf blight |
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| Rows of sclerotia | |
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