Phomopsis stem canker of sunflower

Diaporthe masirevicii is a pathogenic fungus and the primary causal agent of Phomopsis stem canker in sunflower crops. This fungus is highly virulent and capable of causing significant physiological damage, leading to the collapse and death of susceptible host plants.

The fungus specifically targets the sunflower (Helianthus annuus), acting as a systemic pathogen that spreads throughout the plant's vascular system. By invading the internal tissues, it disrupts the flow of water and nutrients, which ultimately leads to a rapid decline in plant health.

Symptoms initially appear as V-shaped brown lesions on the leaf margins, which extend through the leaf stalks to the stem. The stem tissue at the site of infection becomes grayish-brown and necrotic, causing the plant to lose structural integrity and snap under wind pressure.

The spread of Diaporthe masirevicii is heavily dependent on environmental conditions, particularly high humidity and moderate temperatures between 20°C and 25°C. Fungal spores (ascospores) are released from infected crop debris and dispersed by wind or splashing rain to healthy plant tissues.

The economic impact of this disease is severe, often resulting in significant yield losses, reduced seed weight, and lower oil content. In highly infected fields, the damage can jeopardize the entire harvest if proper management practices are not implemented in time.

• Selection and planting of genetically resistant sunflower hybrids.
• Crop rotation with a minimum interval of 6–8 years.
• Deep soil tillage to bury and decompose infected plant residues.
• Application of foliar fungicides during critical growth stages (V4-V6).
• Strict monitoring of the fields for early signs of infection.