Written collaboratively by Emmanuel Byamukama, former SDSU Extension Plant Pathologist and Febina Mathew.
A few corn fields scouted in Brookings County were found with Fusarium root rot at low levels (Figure 1). Infected plants were wilting and upon splitting of the lower nodes revealed brown discoloration of the pith (Figure 2). These symptoms should not be confused with Goss’s wilt, the latter causes systemic infection and symptomatic leaves have water soaking and black freckles. Root and crown rots developing in corn after the seedling stage are usually caused by Fusarium spp. and can be enhanced by injury to the roots or crown, mainly by insect feeding.
Disease Causes
Several Fusarium spp are known to cause root rots in corn, but recent studies at South Dakota State University identified eight species namely Fusarium oxysporum, F. proliferatum, F. acuminatum, F. boothii, F. equiseti-incarnatum complex, F. graminearum, F. solani, and F. subglutinans that were commonly associated with corn root rots. These pathogens survive in soil and crop residue and may infect plants without showing symptoms. Such plants may later develop stalk rots when stressed by excessive moisture or dry conditions.
Management Strategy
- Select hybrids with good Fusarium root rot ratings
- Control root worms and other insects causing injury to the roots
- Improve soil drainage to avoid excessive soil moisture
- Use a fungicide seed treatment for fields with a history of root rots. It should be noted that fungicide seed treatment will not last for the entire season therefore, the above practices should be integrated together for effective management of Fusarium root rots.
Other Resources: Okello et al 2019. Eight species of Fusarium cause root rot of corn (Zea mays) in South Dakota. Plant Health Progress 20: 38-43.
