Botryosphaeria zeae

Botryosphaeria zeae is a pathogenic fungus classified within the kingdom Fungi, class Dothideomycetes, and genus Botryosphaeria. This organism acts as a destructive phytopathogen, primarily targeting maize (corn) crops. Its ability to switch between saprophytic and parasitic growth phases allows it to survive in various environments and significantly impact agricultural production.

The fungus is widely recognized as a causative agent of dry ear rot and stalk rot in maize. Symptoms typically appear on the husks and kernels, often manifesting as localized black lesions and the proliferation of black pycnidia. As the infection progresses, the inner tissues of the cob degrade, leading to poor grain development and structural weakening of the stalks.

The life cycle of Botryosphaeria zeae involves the survival of inoculum in infested plant debris and soil throughout the winter. As temperatures rise and humidity levels increase during the growing season, spores (ascospore and conidia) are released. These spores are disseminated primarily by wind and rain splash, infecting host plants through wounds or natural openings in the ear and stem tissues.

Environmental conditions favoring the rapid spread of the pathogen include warm temperatures, typically ranging from 20°C to 28°C, combined with high moisture. Periods of high humidity during the silking stage significantly increase the risk of infection. Furthermore, drought stress during the grain-filling stage can render plants more vulnerable to successful colonization by the fungus.

The economic impact of this pathogen includes substantial yield losses, reduced grain quality, and the potential for mycotoxin contamination, which creates food safety concerns. Effective control and management strategies are essential for maintaining crop health:

• Planting resistant or tolerant corn hybrids.
• Implementing rigorous crop rotation schedules to break the pathogen life cycle.
• Deep plowing to bury infected crop residues and accelerate decomposition.
• Managing insect populations that cause physical damage to ears and stalks.
• Applying fungicides during critical growth stages when environmental conditions are conducive to infection.