Corn: Diplodia Ear Rot

Excerpt from Agronomy Guide for Field Crops (Chapter 3)

Order OMAFRA Publication 811: Agronomy Guide for Field Crops

Table of Contents

1. Incidence
2. Appearance
3. Disease Cycle
4. Updates on Corn: Diplodia Ear Rot
5. Related links...

Incidence

Of the three primary ear rots that occur in Ontario, Diplodia ear rot is the least common. Diplodia ear rot is caused by Diplodia maydis and favours cool, wet conditions through grain fill.

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Appearance

The characteristic ear symptom is a white mould that begins at the base of the ear and will eventually cover and rot the entire ear. Mould growth can also occur on the outer husk, which has small black bumps (pycnidia) embedded in the mould. These reproductive structures are where new spores are produced. Unlike Gibberella and Fusarium, Diplodia does not produce any known toxins.

Disease Cycle

Overwinters in corn debris left on the soil surface from the previous crop. Spores (conidia) that are produced during wet weather can infect silks and husks or enter through tissue damaged by birds or insects. Ears are most susceptible 3 weeks after.

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Updates on Corn: Diplodia Ear Rot

No updates available at this time.

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Related links...

• Diseases
• Corn
• Field Crop Protection Guide - Publication 812

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