Lasiodiplodia dieback

Lasiodiplodia dieback is a severe fungal disease caused by the pathogen Lasiodiplodia pseudotheobromae. This opportunistic fungus belongs to the Ascomycota phylum and is known for its wide host range, affecting various tropical, subtropical, and temperate plant species, leading to systemic decline and tissue necrosis.

This pathogen poses a significant threat to crops such as mango, citrus, avocado, grapevine, and cocoa. It can infect both young saplings and mature, fruit-bearing trees. By colonizing the vascular system, the fungus disrupts the transport of water and nutrients, which often leads to rapid wilting and eventual death of branches or the entire plant.

Typical symptoms include dark, necrotic lesions on branches and stems, which may progress into severe cankers. In fruit, the fungus causes a soft, dark rot that advances quickly. Infected tissues often exhibit visible gray to black fungal mycelium and pycnidia, which are the reproductive structures of the pathogen used for further dispersal.

The development of the disease is highly favored by warm temperatures and high humidity, which are ideal conditions for fungal spore germination. Infection typically occurs through wounds caused by pruning, insects, or weather-related damage. The pathogen can survive for long periods in infected wood debris and soil, making it a persistent problem in intensive agricultural systems.

Effective management strategies include:

• sanitary pruning of infected branches followed by burning of the debris;
• sterilization of pruning tools between uses to prevent cross-contamination;
• maintaining plant vigor through balanced irrigation and fertilization;
• application of registered fungicides to protect susceptible tissues;
• utilizing disease-free propagation material to prevent initial introduction.