Tolyposporium ehrenbergii
Fungus
This disease is normally restricted to a relatively a small proportion of the florets, transformed into "smut sori", which are scattered on a head. The sori are elongated, more or less cylindrical, elongated, slightly curved fungal structures. They have a relatively thick creamy-brown covering membrane. Each sorus splits at the apex to release a black mass of spores and spread the disease further. About 8-10 dark brown filaments are found within this structure, representing the rests of the plant floral tissues.
Treatment of seeds with organic mercurial compounds is recommended to prevent disease outbreak.
No chemical treatment seems to be available at the moment to treat this disease. Contact us in case you know of any.
The symptoms are caused by the fungus Tolyposporium ehrenbergii. Its spores often stick together to form balls, which allow them to survive in the soil for many years. These spore balls can also adhere to the sorghum seeds and serve as the primary source of infection. The symptoms appear during the booting stage of sorghum, when resting spores germinate within the floral tissues and produce more spores. Those get carried through wind currents to flag leaves on other plants and washed down into the boots to initiate infection of individual spikelets. Airborne spores may also settle and germinate in water droplets accumulated at the flag leaf sheath and infect the opening florets in the panicle later during the season.