Mango leaf spot

Mango leaf spot is a common fungal disease caused by the pathogen Pestalotiopsis mangiferae. It primarily affects the leaves and fruits of mango trees, causing significant tissue necrosis. As a member of the diverse fungal group, it exploits warm and humid conditions to complete its life cycle and spread rapidly within the canopy.

This pathogen specifically targets Mangifera indica but can also be found on a variety of other botanical species in similar climatic zones. The infection process begins when fungal spores land on susceptible plant tissues, germinating under favorable moisture conditions and penetrating the epidermis to colonize the host tissues internally.

The primary clinical signs of the disease are small, irregular brown spots that eventually merge into large, dark lesions. As the infection progresses, the center of these lesions often turns greyish and develops small black dots, which represent the fruiting bodies (acervuli) of the fungus. Severe infections lead to extensive defoliation, which severely stresses the tree's physiological state.

Environmental triggers play a crucial role in the development of Pestalotiopsis mangiferae. High atmospheric humidity, frequent rainfall, and stagnant air within the canopy provide the necessary moisture for spore germination and transmission. The pathogen often persists on infected fallen leaves or dead twigs, allowing it to re-infect the tree during the next growing season.

Economic damage is substantial, as the disease can ruin fruit quality and reduce overall crop yields. Effective disease management requires a multifaceted approach to limit the spread of the fungus and protect healthy tissue:

• Regular pruning of infected branches to improve airflow and reduce inoculum levels.
• Application of protective and systemic fungicides during the onset of the rainy season.
• Sanitation practices, such as removing and destroying all infected plant debris.
• Balanced fertilization to ensure the host plant remains robust against secondary stressors.