Ascochyta stem blight

The disease is caused by the fungus Ascochyta caulicola, which primarily affects legumes, particularly lupines. This pathogen is known for its ability to cause significant damage to the stems, petioles, and seed pods of host plants, leading to severe yield losses in susceptible varieties.

Symptoms of the infection manifest as distinct lesions on the stems, which typically feature light-colored centers with dark brown borders. As the infection progresses, numerous small, dark pycnidia develop within these spots, which are the fungal structures responsible for producing spores and spreading the disease to healthy plants.

The development of the fungus is favored by warm and humid conditions, especially during periods of prolonged rainfall. The pathogen survives the winter season in infected crop debris buried in the soil and can also be seed-borne, which necessitates strict monitoring of seed quality and the implementation of effective crop rotation strategies.

The harmfulness of this disease is linked to the disruption of the vascular system in the plant, which hinders nutrient uptake and water transport. This leads to stem breakage, reduced vigor, and premature senescence of the crop, ultimately impacting both the quality and quantity of the harvest.

Control measures must focus on an integrated strategy: selecting resistant cultivars and using certified disease-free seeds are the first lines of defense. Cultural practices such as burying crop residues through deep plowing and maintaining long intervals between legume crops in the rotation are essential to reduce inoculum levels in the soil.