Bacterial stalk rot

The causal agent of this severe disease is the bacterium Dickeya zeae, which belongs to the Pectobacteriaceae family. It is a highly aggressive pathogen that colonizes the vascular tissues of host plants, leading to the breakdown of cell walls and rapid systemic collapse of the plant structure.

The primary host for this pathogen is maize, but Dickeya zeae is known to have a broad host range, affecting crops such as rice, potatoes, bananas, and various ornamentals. Its ability to infect multiple species makes it a significant threat to international agricultural trade and local food security.

Symptoms of the infection typically include water-soaked lesions that appear on the lower stalk and leaf sheaths, which soon darken and become necrotic. In the advanced stages, the internal stalk pith turns into a mushy, foul-smelling mass. Affected plants often wilt rapidly and lodge due to the loss of structural integrity.

The disease thrives in warm, humid environments, with temperatures between 25 °C and 35 °C being optimal for bacterial multiplication. Spread occurs through contaminated irrigation water, rain splash, infected plant debris, and farm equipment. Insects can also serve as vectors, introducing the bacteria through feeding wounds.

Effective management requires an integrated strategy to minimize pathogen transmission. Key tactics include using certified disease-free seeds, implementing crop rotation to break the infection cycle, improving soil drainage, and rigorous sanitation of fields after harvest to eliminate overwintering bacterial populations.