Strawberry leaf scorch

Strawberry leaf scorch, caused by the fungus Diplocarpon fragariae, is a destructive plant disease affecting commercial and home-grown strawberry plantings. The fungus is an obligate parasite that specifically infects the foliage, petioles, and stolons, leading to reduced plant vigor and significantly lower fruit yields over time.

The primary host for this pathogen is the cultivated strawberry, although it can affect other members of the Fragaria genus. The fungus overwinters in infected leaves that remain on the ground or within the soil, serving as a primary inoculum source when environmental conditions become favorable during the spring growth phase.

Symptoms typically manifest as small, irregular, purple-to-red spots that eventually darken into deep brown or black areas, often giving the leaf a scorched appearance. Unlike other leaf spots, these lesions often lack distinct fruiting bodies at first glance, but the coalescence of spots leads to leaf necrosis, curling, and premature defoliation.

Disease development is highly dependent on humidity and temperature. Optimal conditions for spore germination and infection are prolonged periods of leaf wetness and moderate temperatures, typically ranging from 15 to 25 degrees Celsius. Rain splashes and wind are the primary vectors for dispersing spores from infected foliage to healthy neighboring leaves.

Management strategies focus on sanitation and chemical control. Growers should prioritize the removal and destruction of infected leaf debris after the harvest season to reduce the overwintering population of the fungus. Furthermore, applying fungicides preventatively, particularly during high-risk rainy periods, is essential to minimize the economic impact on the strawberry crop.

• Maintaining proper plant spacing to improve airflow.
• Selecting cultivars with proven resistance to fungal diseases.
• Avoiding overhead irrigation to keep foliage as dry as possible.
• Timely application of protectant fungicides in spring.