Rootless Corn Syndrome
Rootless corn syndrome is a disorder, often a result of hot and dry soil surfaces and planting into dry soil. With rootless corn syndrome, the nodal roots will fail to attach to the soil. Nodal roots are essential conduits for transporting water and nutrients to corn plants. Their absence is highly consequential for the quality of stand and overall yield outcomes.
Dry soils warm more rapidly than moist soils, and combined with conventional tilling, corn plants can become susceptible to failed nodal root development. Heavy rainfall and planting when the soil is too wet can compact the soil, preventing nodal roots from extending downward.
The erosive effects of rainfall and wind combined with shallow planting depth are the primary drivers of rootless corn syndrome. In addition to weather-related causes, when corn is planted at a depth less than 1 inch below the surface, nodal root development can take place at a depth shallower than what is needed for having access to moist soil. Nodal roots should form between 1 to 1.5 inches below the surface.
What to Look for
Nodal roots first appear around the V1 and V2 stage. Rootless corn occurs in plants with poorly developed root systems and is usually observed in plants from about V3 to V8. When rootless corn syndrome is suspected, look for signs of lodged and collapsed corn plants. Corn plants may still be standing but later on they will lose vigor and fall over. Test plants in the area of concern by tugging on them to determine whether nodal roots are established and growing down.
Rootless corn can largely be prevented by ensuring that seeds are planted at least 1.5 to 2 inches below the soil surface. For corn plants whose nodal roots fail to grow, the prospects for survival are bleak. Corn nutrient and water uptake hinges on having a developed nodal root system. For plants that do survive, poor stands and low vigor will be exhibited.
Moving soil to cover roots may allow them to recover – but if an operation is following a no-till plan, this may not be viable. Further, row cultivation for bringing soil around nodal roots will be ineffective if the soil below the surface lacks moisture for supporting recovery. Adequate rainfall and the absence of drought conditions will support optimal nodal root development and prevent rootless corn syndrome.