Strawberry anthracnose

The causative agent of this destructive plant disease is the fungus Colletotrichum simmondsii. It is a highly aggressive pathogen primarily known for causing anthracnose in strawberry plants. The fungus survives in plant debris, soil, and on infected nursery stock, making it a persistent threat that can remain in the field environment for multiple seasons if left unmanaged.

While the pathogen is most commonly associated with strawberries (Fragaria spp.), its host range can be broad. It targets almost all above-ground tissues of the plant, including leaves, stems, petioles, and fruits. The economic impact is severe, as the infection can lead to complete failure of the strawberry crop under favorable environmental conditions.

Symptoms of Colletotrichum simmondsii infection include the appearance of sunken, dark-colored lesions on runners and petioles. As the disease progresses, these lesions may girdle the stem, causing wilting and death of the plant parts above the point of infection. On the fruits, the fungus causes round, depressed lesions that become dark and eventually become covered with masses of fungal spores.

The spread and development of the disease are highly dependent on warm and humid conditions. The pathogen thrives at temperatures between +20°C and +28°C and requires high moisture for spore germination and infection. Rain splash, irrigation water, and even workers moving through the field can easily transfer the sticky spores from one plant to another, leading to rapid disease development.

The impact of anthracnose is devastating, often resulting in significant yield losses and post-harvest decay of berries. Management of this disease requires an integrated pest management (IPM) approach to minimize chemical reliance and maximize efficacy:

• Starting with disease-free certified nursery stock to prevent initial field contamination.
• Implementing drip irrigation to keep foliage and fruits dry and reduce spore splash.
• Sanitation practices, including the removal and destruction of infected plant debris.
• Application of effective fungicides, focusing on protective sprays during flowering and fruit development.
• Promoting good air circulation through proper plant spacing and greenhouse ventilation.