Early Season Root Lodging and Brittle Snap

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.

 

Corn root lodging

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

 

Restricted root growth caused by sidewall compaction at planting

Restricted root growth caused by sidewall compaction at planting

 

Limited brace root development due to dry soil

Limited brace root development due to dry soil

Root Development Stages

The corn plant has 3 different stages of root development during its life cycle.

Seminal roots

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%
Control (no lodging) and plants with simulated wind lodging at V10

Left to right, control (no lodging) and plants with simulated wind lodging at V10, V12, and V16 stages. Lodging occurred in July, photos were taken in early September.

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.

Brittle snap observed at V5 to V8

Brittle snap observed at V5 to V8 often follows a surge in corn growth and development stimulated by favorable rainfall and temperature.

  • 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.
Growing point
  • 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.

Source:

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.

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