The corn plant has 3 different stages of root development during its life cycle.
The earlier that root lodging occurs, the less of an impact it is likely to have on yield.
Corn plants are particularly susceptible to brittle snap damage at V5 to V8, when the growing point is emerging from the soil line.
Carter, P.R. and K.D. Hudelson. 1988. Influence of simulated wind lodging on corn growth and grain yield. J. Prod. Agric. 1:295-299.
Mid-Season Root Lodging and Brittle Snap