Take Steps to Prevent Lodging in Sorghum

By: Brent Bean, Ph.D., Sorghum Checkoff Agronomist

brent bean sorghum storiesLodging can occur with any plant, but unfortunately it can occur in sorghum more than some would want. Some years are worse than others, and in 2015 we saw more lodging in sorghum than in the previous few years. There are two types of lodging – root lodging and stalk lodging.

Root lodging is when the stalk is intact but the plants lodge from the roots. The roots either break off or are pulled loose from the soil, causing the plant to fall over. When this occurs early in the life of the plant, the sorghum will usually recover, although a “bend” in the stalk will remain, which  is called “goosenecking.”

Root lodging can occur on small plants two to three weeks after emergence to any time prior to harvest. When it occurs early, the final yield is generally not affected since the plants quickly begin to grow upright. Root lodging predominantly occurs when soil conditions are wet and very high winds occur. When sorghum is being irrigated, growers should allow the soil to dry between irrigations the first 35 days after planting to encourage the roots to develop deeper into the soil.

Insect feeding on roots can also greatly increase lodging, so seed treatments should be considered.

Stalk lodging

Stalk lodging is when the plant stalk either breaks or bends over and does not recover. This can occur either at the base or higher up on the plant stalk. There are several causes of stalk lodging:

  • High wind speeds.
  • Some hybrids will lodge more than others.  Growers should take the opportunity to review hybrid standability ratings from the 2015 season.
  • Lignin content of the hybrid. It has long been known that lower lignin content is highly correlated to lodging.
  • Plant population. Higher plant populations result in increased lodging potential.
  • Row spacing. Narrow row spacing tends to cause stalks to be smaller in diameter.
  • Stalk borers and diseases.
  • Sugarcane Aphid. Sugarcane aphids left untreated take away valuable nutrients from the sorghum plant causing stress that can lead to an increase in lodging.
  • High soil N levels. High N levels are known to promote lodging.
  • Low soil K levels. K is necessary for normal lignin and cellulose development in plants, enabling them to stand upright and resist lodging.
  • Stresses during grain fill. When sorghum is stressed from lack of water or nutrients during grain fill, starch reserves in the stalk are transported to the grain. This weakens the stalk predisposing the plant to lodging
  • High grain yield. High grain yield in and of itself does not cause lodging, however, when other issues are affecting stalk strength, a high grain yield adds weight to the top of the plant creating more stress on the stalks.

What can you do?

  • Evaluate hybrids for standability, charcoal rot and fusarium.
  • Apply only the amount of nitrogen needed to meet the desired yield goal. This is seldom a problem since most growers under apply N in sorghum.
  • Check soil potassium levels and correct if needed.
  • Do not plant more seed than is needed to reach the desired yield goal.