Lasiodiplodia

The fungus is known for its complex life cycle, existing both as an endophyte within healthy tissues and as a necrotrophic pathogen that triggers plant tissue death. It produces pycnidia, which are structures containing abundant, thick-walled conidia capable of long-distance dissemination.

This pathogen has a wide host range, attacking various crops including grapevine, avocado, mango, cocoa, and various citrus species. It is a major cause of dieback diseases, branch cankers, and root rots, which often lead to the total collapse of the tree architecture.

Beyond field damage, Lasiodiplodia is notorious for causing post-harvest decay, particularly in tropical fruits. This decay can cause significant financial losses during international trade, as infections may remain latent in the field and only manifest after harvest.

The proliferation of Lasiodiplodia is highly dependent on climate conditions. Temperatures between 25°C and 30°C, combined with high relative humidity, create the perfect storm for spore production and the colonization of plant hosts.

Extended dry seasons that lead to drought stress often precede outbreaks, as weakened plants lose their physiological capacity to defend against the fungus. Rainfall then aids in spreading the spores from canopy debris to new, susceptible entry points on the plants.

Infected plants typically show necrotic lesions on stems or trunks, which may develop into elongated cankers. A key diagnostic feature is the presence of gummosis—oozing sap resulting from the plant's stress response to the fungal invasion.

Foliar symptoms usually involve leaf wilting, yellowing, and eventual defoliation. In fruits, the infection presents as rapid rot accompanied by a greyish or black mycelial mass that erupts from the epidermal tissue as the pathogen completes its reproductive cycle.

Effective management requires an integrated approach focusing on sanitation and host resistance. Removing dead or symptomatic wood is critical to reducing the inoculum level in the orchard or field environment.

• Regular pruning of infected branches and destruction of debris.
• Wound protection using wound-sealing pastes or fungicides.
• Improving plant vigor through balanced fertilization and correct irrigation.
• Fungicide applications during high-risk periods to protect wounds from infection.