Zonate leaf spot - Gleocercospora sorghi
Sorghum- Sorghum vulgare
Lesions begin as small circles then expand to form alternating circular bands of reddish-black and gray dead tissue. Lesions have an irregular edge. Pink to salmon colored fruiting bodies consisting of small masses of fungal tissue called sporodochia produce masses of very long, narrow spores on the dead tissue. These asexual conidia are colorless with 4 to 14 cross walls (septa). Conidia are spread by wind and rain to other leaves or neighboring plants. Small black sclerotia form in the old dead tissue along the veins and serve as survival structures. G. sorghi can also attack millet and other grasses. Zonate leaf spot can substantially reduce forage and seed yield. Crop rotation and deep tillage of residues are the primary management methods.
Compiled by: Barry M. Cunfer, UGA Plant Pathologist, Griffin, GA