Diplodia seriata

Diplodia seriata is a significant fungal plant pathogen belonging to the family Botryosphaeriaceae. It is widely recognized as a causal agent of wood-decay diseases, including Botryosphaeria dieback and various forms of trunk necrosis, which significantly impact the longevity and productivity of woody perennial crops worldwide.

The host range of Diplodia seriata is extensive, primarily affecting grapevines, apple trees, pears, and walnut trees. On grapevines, the fungus is a key member of the complex associated with grapevine trunk diseases, leading to systemic necrosis, vascular browning, and eventual vine death. In fruit orchards, it manifests as cankers on branches and stems, often resulting in severe dieback.

The biology of the pathogen involves both sexual and asexual reproduction cycles. The fungus produces conidia, which are disseminated by rain splash and wind, facilitating rapid spread within a plantation during the growing season. It often persists in the plant tissue as an endophyte, remaining dormant until the plant experiences stress, at which point the fungus becomes pathogenic.

Environmental factors, particularly humidity and temperature, play a crucial role in the infection process. Infection typically occurs through natural openings or man-made wounds, such as pruning cuts or winter frost cracks. Once inside the wood, the mycelium colonizes the vascular tissues, effectively blocking water and nutrient transport, which inevitably leads to the symptoms of decline.

Managing Diplodia seriata requires an integrated approach focusing on prevention and hygiene. Key control strategies include:

• systematic removal and destruction of infected wood to reduce inoculum;
• disinfection of pruning tools between vines or trees to prevent mechanical spread;
• application of wound protectants to large pruning cuts;
• application of preventative fungicide treatments during susceptible periods.