Phoma Stem Canker

The causative agent of this disease is the fungus Plenodomus fallaciosus, a member of the ascomycetes class. This pathogen is known for its ability to cause severe necrotic lesions on the stems, leaves, and basal tissues of various agricultural crops, significantly impacting overall plant health and development.

The disease primarily targets crops within the Brassicaceae family, including canola, mustard, and various vegetable brassicas. It represents a significant threat to commercial production, as the pathogen can infect plants at different stages of their life cycle, from early seedling emergence to the late maturation phase.

Symptoms of the infection typically appear as dark, oval-shaped lesions on stems or leaf petioles. As the disease progresses, the centers of these lesions become lighter in color and become speckled with numerous small black structures known as pycnidia, which serve as the primary diagnostic feature of the fungus.

Environmental conditions characterized by high humidity and moderate temperatures ranging from 15°C to 25°C are optimal for the growth and spread of Plenodomus fallaciosus. The fungus persists in infected crop residues in the soil and on seeds, making it a recurring challenge in fields where host crops are grown frequently.

The economic impact is substantial, as the disease leads to stem breakage, lodging, and poor seed development. Severe infestations can cause significant yield losses and lower the overall quality of the harvest, making consistent monitoring and integrated management strategies essential for farmers and agronomists.

• Practicing crop rotation by planting non-host species for at least 3-4 years to reduce inoculum.
• Ensuring the use of certified, disease-free seed lots that have been properly treated.
• Effective tillage practices to promote the decomposition of infected plant debris.
• Strategic application of foliar fungicides during peak disease risk periods to minimize damage.