There are a number of soil borne pathogens that can cause damping off in Spring planted corn. (i.e. Fusarium spp., Pythium spp., and Rhizoctonia spp.). Environmental factors such as cool, wet soils can exacerbate disease incidence and severity. Cold temperatures slow down the growth and development of corn and allows more time for pathogens to find and infect the seedling. Excess soil moisture can leach fungicide seed treatments away from the seed and reduce efficacy. Furthermore, pathogens such as Pythium spp. require soil moisture for the motility of their infections parts (zoospores). Poorly drained soils may have a higher incidence of root rot and seedling damping off caused by Pythium sp. If you experience seedling damping off, it is a good idea to submit a sample for diagnosis. Management recommendations will be different based on the type of pathogen present in your field. For confirmation of disease, consider submitting a sample to the UF Plant Diagnostic Center. Click on the link in blue below for more information on submitting a plant sample for disease diagnosis.
What To Look For
- Plants that have not emerged (row skips)
- Seed rot prior to germination
- Seed rot or discoloration after germination but prior to emergence
- Post-emergence seedling damping off
- Decay on the root or hypocotyl
Currently there are no corn hybrids with good resistance to seedling diseases. Disease can be mitigated by improving soil drainage, planting at the correct depth and delaying planting until soil temperatures are more conducive to rapid germination and growth. Corn prefers a planting depth of 2″ and a soil temperature of ~55°F or higher.
Seed treatment fungicides can be used to effectively control seedling diseases. Unfortunately, disease can still occur under high pathogen pressure or if weather conditions are conducive to disease development (long periods of cool, wet weather).
Rotating crops to non-hosts can provide some control; however, some of the pathogens that cause seedling diseases in corn can also infect other plant species. This is another reason that getting an official diagnosis can be helpful in managing diseases in your fields.
For more information on corn seedling diseases contact Dr. Kevin Korus.
UF/IFAS Extension, Alachua County.