The onset of Diplodia stalk rot is marked by the premature death of the plant. The leaves transition to a dull gray-green color before wilting and drying up. The lower internodes of the stalk soften and turn a tan to brown color, while the stalk's pith discolors and disintegrates, leaving only the vascular bundles.

When you split the stalk, you may observe a white to pinkish mold growing between the nodes, particularly at the stalk's base. Tiny, black fungal structures called pycnidia can be found scattered on the lower internodes and on the outer husks of the ear. These pycnidia serve as a key diagnostic feature of the disease.

To ascertain the presence of Diplodia stalk rot, conduct a simple test. Place the suspected stalk or ear in a plastic bag with a wet paper towel and seal it. If Diplodia is present, white mold will develop within 24 to 48 hours.

While Diplodia stalk rot is most common in the Midwestern United States, it can strike wherever corn grows. It is more prevalent in areas with high humidity and rainfall.

Diplodia stalk rot can infect corn at any growth stage, but symptoms typically emerge after tasseling. The disease intensifies during and after silking in years with wet weather.

The disease intensifies in continuous corn fields and fields where corn residue remains on the surface, as the fungus overwinters in this residue and infects the subsequent crop.

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