Heart rot

Heart rot is a debilitating plant disease caused by the fungus Oxyporus latemarginatus. As a wood-decay pathogen, it targets the heartwood of trees, breaking down structural components and compromising the health and stability of the host plant over an extended period.

This fungus is known to affect a variety of significant crops, including Citrus species, coconut palms, and avocado trees. It typically enters the plant through wounds caused by pruning, environmental stress (such as frost cracks), or insect damage, establishing itself deep within the woody tissue where it remains protected.

The visual symptoms of an infection are often subtle until the disease is advanced. Affected trees may show canopy thinning, yellowing leaves, and general lack of vigor. In many cases, the definitive sign is the appearance of fungal conks (fruiting bodies) on the trunk or base of the tree, which indicates significant internal decay.

The development of Oxyporus latemarginatus is favored by high moisture levels and poor drainage conditions. The fungus propagates through wind-borne or water-splashed spores, making it highly contagious within orchards if infected debris is left on the ground or if pruning practices are not strictly hygienic.

Management strategies focus on prevention and sanitation, as there is currently no cure for deeply established internal heart rot. Essential practices include:

• Strict sterilization of pruning equipment between different trees to prevent cross-contamination.
• Prompt treatment of all mechanical wounds and cuts with protective sealants.
• Monitoring orchards for early signs of decay to facilitate the quick removal of infected trees.
• Improving soil aeration and drainage to reduce moisture stress on the root system.