Leptosphaeria stem canker

The pathogen Leptosphaeria fusispora is a significant fungal threat to various Brassicaceae species. As an ascomycete fungus, it completes its life cycle by forming both asexual pycnidia and sexual pseudothecia, which allow it to overwinter successfully on crop stubble, ensuring long-term persistence in agricultural soils.

This pathogen primarily targets cruciferous crops, including winter oilseed rape, cabbage, and mustard. The fungus is capable of infecting all developmental stages of the host, from seedlings to mature plants. The systemic nature of the infection allows the pathogen to colonize the vascular tissues, leading to severe physiological disruptions.

Symptoms often manifest as leaf spots with light centers and dark borders, containing black pycnidia. The most damaging phase involves infection at the stem base, causing significant cankers. These necrotic lesions weaken the stem, making the plants prone to lodging and pre-harvest collapse, which significantly reduces yield potential.

The development and spread of Leptosphaeria fusispora are highly dependent on environmental factors, particularly moisture and temperature. Spores are disseminated by rain splash and wind over varying distances. Dense canopy conditions and high humidity create a favorable microclimate for rapid disease progression within the field.

To mitigate the impact of this disease on crop productivity, integrated pest management (IPM) practices are essential. Effective strategies include:

• Planting certified, fungicide-treated seeds.
• Implementing strict crop rotation (at least 3–4 years between host crops).
• Removing volunteer plants that act as a green bridge for the pathogen.
• Applying preventive and curative fungicides at critical growth stages.
• Selecting varieties with genetically determined resistance to stem canker.