Strawberry leaf spot (Phyllosticta)

Phyllosticta leaf spot is a fungal disease affecting strawberry plants, caused by the pathogen Phyllosticta fragariicola. This disease primarily targets the foliage, resulting in necrotic spots that disrupt the plant's physiological processes and overall vigor during the growing season.

The disease is host-specific, mainly impacting various species within the Fragaria genus. While it is rarely lethal, severe infections can cause significant defoliation, which reduces the plant's energy reserves and negatively affects fruit production and winter hardiness.

Symptoms are identified by the development of circular or irregular necrotic spots on the leaf blades. These spots initially appear reddish-brown or dark brown with a distinct purplish border. As the lesions mature, the center turns light brown or grayish, and tiny black structures called pycnidia become visible under magnification.

Development is favored by warm, humid conditions and stagnant air circulation within the planting beds. The pathogen survives the winter in infected leaf debris and soil. When environmental conditions improve in the spring, the fungus releases spores that are spread by rain splashes, wind, or agricultural equipment, leading to new infections.

Effective management requires a combination of sanitation and chemical controls. Key strategies include:

• Regular removal and destruction of infected leaf litter.
• Ensuring adequate spacing between plants to improve airflow.
• Rotation of crops to avoid soil-borne inoculum buildup.
• Application of protective fungicides during periods of high humidity.