Diplodia ear rot

Systematic position and nature of the pathogen: Stenocarpella zeae (formerly known as Diplodia maydis) is a fungus belonging to the Ascomycota division. It is the primary causal agent of Diplodia ear rot and stalk rot in maize, representing a significant threat to global corn production.

Symptoms and host crops: The pathogen primarily affects maize. Symptoms include a white, moldy growth appearing on the ear, typically starting at the base. In severe cases, the entire ear becomes mummified, light in weight, and covered in tiny, black reproductive structures called pycnidia.

Biology and life cycle: The fungus survives the winter as pycnidia and mycelium on infected crop debris left on the soil surface. During periods of wet, warm weather in the growing season, spores (conidia) are dispersed by wind and splashing water to healthy plants, initiating new infection cycles.

Environmental conditions and impact: Disease development is favored by warm temperatures and frequent rainfall, especially during the silking stage of corn. The impact is significant, as the infection leads to reduced grain yield, poor grain fill, and potential contamination with mycotoxins, which can render the harvest unsuitable for feed or food processing.

Protection and control measures: Effective management requires an integrated approach. Farmers should prioritize the use of resistant maize hybrids and ensure high-quality seed treatment. Additionally, tillage practices that bury crop residue help reduce the primary inoculum, while crop rotation breaks the cycle of disease persistence.

• Selection of hybrids with tighter husks to reduce ear infection.
• Proper disposal or burial of infected corn stalks.
• Avoidance of continuous corn cropping in high-risk areas.