Gray ear rot

Gray ear rot is a fungal disease affecting corn, caused by the pathogen Botryosphaeria zeae. It is a significant concern for maize production, particularly in areas with humid climates, as it directly impacts the quality and yield of the harvested crop.

The primary host for this pathogen is maize (corn). The fungus survives on crop debris left in the field and within the soil profile. Because it can persist through the winter, it poses a recurring threat to fields where corn is grown continuously without adequate crop rotation.

Symptoms typically manifest as a gray or ash-colored mold covering the surface of the ear. As the infection progresses, the kernels become discolored and brittle, and the internal cob tissue decays. In severe cases, the entire ear can be colonized, leading to extensive rotting and significant weight loss.

The development of the disease is highly dependent on environmental factors, specifically high moisture and warm temperatures during the late silking and grain-filling stages. Mechanical damage to the ears, often caused by corn earworms or other pests, significantly increases the risk of infection by providing entry points for the fungal spores.

• Implement crop rotation with non-host plants.
• Ensure thorough tillage to bury infected plant residues.
• Select corn hybrids with improved husk coverage and resistance.
• Manage corn pests to reduce entry points for the fungus.
• Harvest as early as possible to avoid late-season exposure.

Gray ear rot can reduce not only yield but also the overall feeding value of the corn grain. Effective management requires an integrated strategy, focusing on cultural practices to reduce inoculum loads and selecting the right genetic material to withstand pathogen pressure in susceptible regions.