By Scout Nelson
A rare crop disease known as sorghum ergot has reemerged in Nebraska fields after more than a decade. The disease, caused by Claviceps africana, is commonly seen in southern states but rarely affects crops in the northern Great Plains. Experts attribute its spread to persistent southern winds and humid weather conditions.
This year, sorghum ergot has been confirmed in Kansas and detected in forage sorghum in Nebraska. The last reported case in the region was in 2014, making this resurgence an unusual event.
The disease infects sorghum flowers, filling the ovaries, and preventing seed development. It produces sticky, amber-coloured “honeydew” droplets that attract insects and make plant surfaces shiny or sticky. As the droplets dry, they leave white or tan speckles on the leaves. Spores within the honeydew can spread to other plants through rain or wind, further increasing the risk of infection.
Favorable conditions for sorghum ergot include cool, humid weather with nighttime temperatures between 50°F and 55°F during flowering. However, unlike ergot in wheat or rye, this type of fungus rarely produces toxic alkaloids. Since 1997, no toxic sclerotia has been detected in Nebraska, meaning affected crops remain safe for livestock feed.
Male-sterile forage sorghum varieties are particularly susceptible, while related species such as Johnsongrass and volunteer sorghum can also host the disease. At this stage, fungicide treatments are ineffective, so management focuses on careful harvesting.
Producers are advised to delay harvest until after rainfall or frost to reduce sticky residues and ease mechanical handling. Harvesting forage before heading can also prevent infection. For quality assurance, infected portions should be stored separately and tested if contamination is suspected.
The University of Missouri’s Veterinary Medical Diagnostic Laboratory offers testing for ergot alkaloids in both grain and forage. Nebraska producers can contact their local Extension office or the UNL Plant and Pest Diagnostic Clinic for guidance and sample submission.
Photo Credit:istock-mailson-pignata
Categories: Nebraska, Crops, Sorghum