Corn Plants Leafing Out Underground 

This can be a problem due to several factors or conditions:

Light can penetrate through the soil surface of a cloddy seedbed. The corn plant spiking through the soil hits the sunlight and leaves unfurl before they reach the soil surface.

Sandy, course textured soils becoming very warm at the soil surface (0-1" depth) which can cause the coleoptile to stop growing and leaves unfurl below ground.

Environmental stresses, caused by cold and/or compacted soils, can slow emergence and cause plants to leaf out prematurely. Herbicide stress and/or deep planting can compound the problem. Damaged plants may not produce a healthy ear even if they do manage to emerge and survive.

Excessive herbicide rates of Eradicane, Sutan, Lasso or Dual on light, sandy soil also can cause this problem.

Corn seed maggot can injure seedling, prevent emergence.

Occasionally poor seed quality and vigor can be a problem.