Ophiobolus stem canker

Ophiobolus stem canker is a destructive fungal disease caused by fungi belonging to the Ophiobolus genus. This pathogen primarily attacks the stem and vascular tissues of various plant species, disrupting the nutrient and water flow, which often leads to plant lodging, wilting, and premature death of the affected crops.

The disease has a significant impact on several agricultural crops, including industrial hemp (Cannabis sativa). The pathogen acts as a soil-borne fungus that survives on crop debris, making it a persistent threat in regions where monocropping or short-rotation practices are common.

Symptoms initially appear as dark, necrotic lesions near the soil line or on the lower stem segments. As the canker expands, it girdles the stem, compromising structural integrity. Advanced stages of infection often show tissue necrosis, internal stem rotting, and a characteristic chlorosis or yellowing of the foliage, eventually resulting in stunted growth and significant yield losses.

Environmental conditions play a crucial role in the development of the disease. High soil moisture, moderate temperatures, and poor field drainage create ideal conditions for spore germination and infection. Furthermore, spread occurs primarily through contaminated soil movement, infected seed lots, and farm equipment that carries fungal spores from infested areas to healthy fields.

Managing Ophiobolus stem canker requires an integrated approach. The most effective preventative measure is a well-planned crop rotation strategy to break the pathogen's life cycle. Deep tillage helps bury infected organic matter, speeding up decomposition. Additionally, the application of targeted fungicides during seed treatment and early growth stages is essential for maintaining crop health in high-risk environments.

• Implement crop rotation for 3–4 year cycles.
• Deep plowing to incorporate and decompose crop residues.
• Apply systemic fungicides to seeds before planting.
• Improve field drainage to reduce soil humidity.