Brown spot of lupin

The disease known as brown spot of lupin is caused by the fungus Pleiochaeta setosa. This pathogen is a significant limiting factor in the successful cultivation of lupin crops worldwide, as it affects both the yield quantity and the overall quality of the harvested produce.

The fungus is capable of infecting all parts of the lupin plant, including the roots, stems, leaves, and pods. Severe infections often manifest during the seedling stage, causing root rot and damping-off, which leads to substantial crop failure and reduced plant density across the field.

Symptoms are identified by dark brown to black lesions. On stems and roots, these lesions appear as deep, necrotic cankers. On leaves, the spots are initially small but expand rapidly, coalescing to kill the leaf tissue. This process significantly weakens the plant, inhibiting its ability to perform photosynthesis and leading to premature senescence.

Development of Pleiochaeta setosa is favored by wet, cool to temperate conditions. The pathogen can survive for extended periods in crop debris and within the soil profile, utilizing resistant resting structures. Furthermore, the fungus is seed-borne, which facilitates long-distance transmission and introduces the pathogen into previously uncontaminated fields.

Integrated management is essential for controlling this disease. Effective strategies include a strict crop rotation of at least five to seven years, as the pathogen persists in the soil. Additionally, farmers should prioritize the use of high-quality, fungicide-treated seeds and select lupin varieties known for their tolerance or resistance to this specific pathogen.

• Strict adherence to crop rotation cycles.
• Use of certified pathogen-free seeds.
• Chemical seed treatments before sowing.
• Management of crop residue through deep plowing.
• Application of foliar fungicides under high-pressure conditions.