Phomopsis leaf blight

Phomopsis leaf blight is a fungal disease caused by the pathogen Dendrophoma obscurans. This infection is a common issue in strawberry cultivation, affecting the foliage and potentially damaging the plant's overall health and physiological development by reducing the surface area available for photosynthesis.

The primary host for this pathogen is the strawberry (Fragaria) plant. While it predominantly affects the leaves, in conditions of severe stress or high humidity, the fungus can colonize runners, petioles, and calyxes, leading to a general decline in plant vitality.

Symptoms typically start as round or irregular spots that are reddish-brown in color. As the infection progresses, the centers of these spots become necrotic and turn light brown or gray, often surrounded by a distinct dark purple or reddish margin. Under close inspection, tiny black pycnidia (fruiting bodies) can be seen clustered in the center of the older spots.

The disease cycle is heavily influenced by environmental factors such as moisture and temperature. Spores are primarily dispersed through splashing water during irrigation or rainfall. The pathogen survives the winter in infected leaf litter, making sanitation a critical component of the management strategy to prevent recurring outbreaks in subsequent seasons.

To control Phomopsis leaf blight, integrated pest management practices are recommended. This includes the removal and destruction of dead foliage, ensuring proper spacing between plants to improve airflow, and the use of protective fungicide applications. Selecting resistant cultivars is another essential step in preventing significant economic loss in commercial strawberry production.