Stenocarpella maydis, syn. Diplodia maydis, S. macrospora, syn. D. macrospora

Nature of damage

• Infection of the stalk leads to disruptions in the translocation of water and nutrients, resulting in yield loss.
• It also predisposes plants to crop lodging, bringing about premature plant death and yield loss.

Signs

• In susceptible cultivars it causes browning of the pith of basal internodes.
• Stalks are weakened and break easily during strong winds and rains.
• Late in the season, the most conspicuous symptom is the abundant formation of spore structures known as pycnidia on the surface of internodes where rotting has occurred.

Factors favoring development

• Dry weather early in the growing season followed by frequent rainfall after silking 
• High plant density.
• Low potassium content in the soil.

Geographic distribution

• Stalk rot is caused by S. maydis in cool, humid temperate areas, and by S. macrospora in warm, humid zones.

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