Corn smut is caused by the fungal pathogen Ustilago maydis.
Spores are spread through wind or water splashing to nearby plants.
This pathogen infects the corn through the silks prior to pollination, or by wounds on the plant (Fig 3).

Identification

Corn smut is easily identified by rapid swelling, known as galling, on ears, stalks, leaves, and tassels (Fig 1).
Galls become papery and produce black teliospores (Fig 2).

Fig 1: Galls caused by Ustilago maydis on corn ears

Fig 2: Masses of teliospores resemble black soot

Fig 3: Corn smut growth at base of a previously damaged stalk

Management

Resistant varieties are available, consult local seed representatives to discuss hybrid options.
Early planting dates can minimize the window silks are susceptible to spores.
Crop rotation can disfavor the pathogen by removing a susceptible host from the affected region.

References

Crop Protection Network . (2022, January 27).Common Smut of Corn.Retrieved from Crop Protection Network: https://cropprotectionnetwork.org/encyclopedia/common-smut-of-corn

Pataky, J. K., and K. M. Snetselaar. 2006. Common smut of corn.The Plant Health Instructor. DOI:10.1094/PHI-I-2006-0927-01

Authors: Madeline Henrickson and Dr. Alyssa Koehler

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