Guava anthracnose

The fungal pathogen Colletotrichum guajavae is the causative agent of guava anthracnose, a destructive disease that significantly impacts the commercial production of guava fruits worldwide. This fungus belongs to the genus Colletotrichum, which is notorious for causing various fruit rots in tropical and subtropical regions.

The host range of Colletotrichum guajavae is primarily centered on Psidium guajava (guava), where it causes severe yield losses. The infection can affect all aerial parts of the tree, including tender stems, flowers, and mature fruits, leading to fruit decay both in the field and during the post-harvest storage phase.

Symptoms initially appear as small, water-soaked lesions on the fruit surface. As the disease progresses, these lesions turn dark brown or black, become sunken, and eventually develop concentric rings of salmon-pink spore masses. Leaf infections manifest as irregular necrotic spots, which can cause significant premature defoliation and canopy dieback.

The development of the disease is highly favored by high relative humidity, frequent rainfall, and warm temperatures, which facilitate the germination of conidia. Spores are primarily disseminated by wind-driven rain, splashing water, and contaminated tools used for pruning or harvesting, allowing the pathogen to spread rapidly through an orchard.

Effective management requires an integrated pest management approach focusing on prevention and reduction of inoculum levels:

• pruning infected branches to improve orchard ventilation;
• maintaining strict sanitation by removing and destroying all infected debris;
• applying appropriate prophylactic fungicides during high-risk moisture periods;
• ensuring proper fruit handling and storage to minimize post-harvest losses.