Diaporthe dieback

Diaporthe rudis is a fungal pathogen responsible for causing dieback and various necrotic lesions on a wide range of woody plants. As an ascomycete fungus, it primarily targets the vascular system of the host plant, leading to compromised nutrient transport and eventual death of the affected tissues or individual stems.

The host range of Diaporthe rudis includes commercially significant berry crops such as highbush blueberries, blackberries, and grapes. It also poses a threat to various ornamental shrubs in landscapes. The fungus is persistent and can remain latent within plant tissues until conditions favor its rapid proliferation and sporulation.

Symptoms typically present as dark, sunken lesions on stems and canes, which may eventually lead to bark splitting. Infected plants often exhibit wilting leaves and stunted growth. As the disease progresses, characteristic small, black, dot-like fruiting structures known as pycnidia develop on the dead bark surface, signaling the maturity of the fungal life cycle.

Environmental conditions play a critical role in the development of Diaporthe rudis. High humidity, mild temperatures, and frequent rainfall create the ideal climate for spore germination and infection. Mechanical wounds caused by winter pruning, frost damage, or insect activity serve as the primary entry points for the pathogen to colonize the plant.

Management of the disease requires a rigorous integrated pest management approach. This includes meticulous pruning of infected wood, cleaning tools with bleach or alcohol to prevent cross-contamination, and applying fungicides strategically. Protecting the plant from excessive moisture and ensuring proper spacing between plants are essential to reduce the overall disease pressure in the field.

• Remove and destroy all infected plant material immediately.
• Sanitize all pruning tools between plants to prevent spread.
• Improve air circulation through proper pruning and spacing.
• Select resistant varieties where possible for cultivation.
• Apply preventative fungicide programs during the growing season.