You can’t construct a strong building on a weak foundation, and you can’t grow a great corn crop on a weak root system. From freezing temperatures to voracious underground pests and other threats, corn roots are often under attack.
A corn plant’s overall health—and potential yield—starts with its root system. Healthy corn roots enable efficient resource uptake and use, anchor the plant in the ground and protect the plant against pests and disease.
How can you protect corn root health and, in doing so, improve the plant’s overall health and eventual yield?
Understanding corn roots and their roles
- Seminal corn roots: The seminal roots comprise the first corn plant root system that develops. These roots anchor the seedling and provide water and nutrients to sustain it in the weeks after emergence. Once the seedling has emerged, seminal root growth slows.
- Nodal corn roots: Nodal root growth begins after the coleoptile emerges from the soil and provides the majority of water and the mineral nutrients needed for corn growth and development after the V6 corn growth stage.
- Brace corn roots: These roots develop in late V growth stages, reaching downward from above the soil line and giving the appearance of their namesake brace. Like nodal roots, brace roots also take up water and nutrients.
How damage to corn roots can impact yield
Corn root damage affects yield differently at different growth stages.
Seminal root damage
Freezing temperatures and fertilizer injury are both common sources of early-season injury for the radicle (the first root of a corn plant) or lateral seminal roots (roots that emerge from the seed embryo behind the coleoptile). This damage does not cause immediate seedling death as long as the kernel and mesocotyl remain healthy. However, damage can stunt initial seedling development, delay emergence, kill the radicle root and cause leafing out underground.
The longer the corn plant grows and establishes nodal roots, the less impact seminal root damage has on seedling survival and final yield.
Nodal root damage
Nodal root damage during V1 and V5 growth stages can delay development and severely stunt corn plants. Around the V3 growth stage, corn is transitioning from relying on kernel reserves to relying on nodal roots. If the first few sets of nodal roots are damaged, the young seedling is forced to depend on kernel reserves longer than it ideally would.
Rootless corn syndrome
Conditions such as hot, dry surface soils, shallow planting depth, soil compaction, and loose or cloddy soils during nodal root development can lead to rootless corn syndrome. As the name suggests, this occurs when corn plants have limited or nearly no nodal root development. Rootless corn syndrome is typically observed at the three- to eight-leaf stage of corn development.
Lodging is a common result of rootless corn syndrome, and dry conditions can significantly reduce the likelihood of plant recovery after lodging. Rain can help promote nodal root development and establishment and moisten the seedbed, aiding in plant recovery. Cultivation to move soil around exposed roots can also help recovery, but if plants are already lodged and laying flat, this is difficult.¹
Corn rootworm damage
Root pruning from corn rootworm can cause significant yield loss. Recent research predicts up to 15% yield loss for every node pruned back to 1.5" of the stalk.²
Damage from larval corn rootworm will appear as brown root tips and roots that are tunneled into and even chewed back to the base of the plant.
This root pruning inhibits the plant’s water and nutrient uptake, often resulting in yield reductions in situations where other stressors are present.³ Dry conditions can increase the yield impact of root pruning, and rootworm damage can lead to lodging.
How to manage corn root damage from rootworm
While many causes of corn root damage are out of your control, you can control corn rootworm through a combination of cultural, chemical and seed-based management tactics.
Interrupting the pest’s life cycle by rotating to non-host crops is a key management tactic to control corn rootworm.
Bt corn hybrids with below ground traits specific for corn rootworm have proven effective for managing rootworm species. It is always recommended to alternate planting Bt corn with non-Bt corn to slow the acceleration of Bt resistance in corn rootworm and other insect species.
Experts are available to help you make your decisions. Reach out to your seed retailer, a nearby extension office agent, or a seed company professional like your regional BASF representative.
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Endnotes
- “Rootless Corn Syndrome.” Integrated Crop Management, Iowa State University, crops.extension.iastate.edu/encyclopedia/rootless-corn-syndrome-0. Accessed 21 Nov. 2024.
- Dean, Ashley, and Erin Hodgson. “It’s Time to Check Whether Corn Rootworm Management Worked.” Integrated Crop Management, Iowa State University, 26 June 2023, crops.extension.iastate.edu/cropnews/2023/06/its-time-check-whether-corn-rootworm-management-worked. Accessed 21 Nov. 2024.
- “Corn Rootworms.” Purdue University - College of Agriculture, ag.purdue.edu/department/entm/extension/field-crops-ipm/corn/corn-rootworms.html. Accessed 21 Nov. 2024.
