Identify reason stalks fall over

Lodging in corn can cause slowdowns at harvest and yield loss. There are two types of lodging — root lodging and stalk lodging. Each is caused by a different set of factors.

Root lodging may be caused by genetic weakness in root strength. Corn breeders consider a plant root-lodged if it’s leaning away from the straight, vertical position by more than 30 degrees.

The hybrid may have a very good root system belowground, but may not have good brace roots.

Rains followed by winds can also cause root lodging. If it occurs when plants are young, they can recover by elbowing and straightening up.

Key Points

• Genetics can play a role in both root lodging and stalk lodging.

• Plants that are root-lodged by weather may elbow and recover.

• Various, distinctive fungal diseases can cause stalk rot.

Factors behind stalk lodging

When a plant is broken below the top ear, agronomists call it stalk-lodged. It may also be caused by genetic weakness, environmental factors, or both.

Genetic stalk strength or weakness may be determined by rind thickness, density of pith tissue, ear height and susceptibility to disease organisms.

Plants affected by leaf diseases become more prone to stalk rots. Rot is often caused by fungal diseases, like anthracnose, gibberella or diplodia.

Anthracnose has a leaf-blight phase and a stalk-rot phase. The leaf blight stage produces long, irregular lesions. Stalk rot affects the pith, which eventually becomes black. The outside of stalks can become black and shiny.

Diplodia stalk rot is favored by hot, humid weather. Nodes and pith disintegrate. The pith has a whitish-brown appearance. Stalks break easily when pushed. Hot, humid weather in late summer also spreads gibberella. Stalks are pinkish when cut open.

Planting disease-resistant hybrids is your first line of defense. Higher plant density causes stress on plants. Insect feeding can open entry points.

Nanda writes from Indianapolis.

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Out and up: These root-lodged plants elbowed, but recovered.

09103441b.tif

Party is over: Note the severe, blackish anthracnose organisms. Stalk rot could severely limit yield.

This article published in the September, 2010 edition of INDIANA PRAIRIE FARMER.

All rights reserved. Copyright Farm Progress Cos. 2010.