Early Season Root Lodging and Brittle Snap

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Summary

Root lodging often occurs in late June and early July when thunderstorms are likely and brace roots are not yet fully developed.
Wind-induced root lodging is not always related to root injury, but is more likely to occur when root systems are damaged or restricted.

Potential Contributing Factors to Early Season Root Lodging

Compacted soil around the root zone due to wet conditions at planting, resulting in restricted root development
Wet soil early in the season, reducing the need for root expansion
Dry soils later in the season that slow down brace root development
Restricted root development due to unfavorable soil conditions during early nodal root growth
Reduced root growth due to nitrogen deficiency
Water-saturated soils at the time of a wind event

Root Lodging Damage

The earlier that root lodging occurs, the less of an impact it is likely to have on yield.

In a 2-year study of simulated wind lodging, yield was reduced by 3%-4% with lodging at V10 to V12
Lodging at V13 to V15 reduced yield by 10%

Brittle Snap Damage

Corn plants are particularly susceptible to brittle snap damage at V5 to V8, when the growing point is emerging from the soil line.

A corn plant at V5 (five visible leaf collars) is entering a period of rapid growth
Stalk growth occurs by elongation of internode cells, which increases the rigidity of the stalk. Cell walls are extremely fragile at this stage.
At the V5 to V8 stage many nodes and internodes are arranged together in a small area (see image below). This dense concentration may make the plants less flexible and more susceptible to breakage.
Brittle snap breakage at V5 to V8 occurs below the growing point, at a stalk node at or near the soil surface. Snapped plants will not recover, nor contribute appreciably to yield.

Many factors affect the severity of brittle snap injury, including growing conditions, field geography, crop management practices, soil type and hybrid genetics.
Growth regulator herbicides can increase the incidence and severity of brittle snap injury by impacting cell division in the nodal area and increasing stalk brittleness.
Growers should plant a package of hybrids and manage growth regulator herbicides carefully to spread the risk of brittle snap.

Summary