Stigmina spot of cashew

Stigmina spot is a fungal disease affecting cashew trees, primarily caused by the pathogen Stigmina anacardii. This fungus acts as a specialized leaf spot agent, targeting the foliage of its host plant. By disrupting the leaf tissue, the fungus interferes with the plant's photosynthetic efficiency and overall growth potential.

The primary host for this pathogen is the cashew tree (Anacardium occidentale). Given the global importance of cashew production, understanding this disease is critical for plantation management in tropical regions. The disease manifests in plantations where environmental conditions consistently favor the development of various fungal pathogens.

The symptoms of Stigmina anacardii infection include distinct spots on the leaf blades. Initially, these spots appear as small, chlorotic lesions. As the infection progresses, the lesions enlarge, turn brown or grayish, and often develop a necrotic center. Severe infestations can lead to heavy leaf drop, which weakens the tree and significantly impacts the production of the cashew nut.

Environmental conditions are the main drivers of disease spread. The fungus thrives in environments with high relative humidity and frequent rainfall. These conditions facilitate the germination of spores and their subsequent dispersal through wind and splashing raindrops. Consequently, dense plantations with poor airflow are particularly vulnerable to rapid disease outbreaks.

Managing the disease requires an integrated approach to protect the health of the trees. Key practices include:

• Sanitary pruning of infected branches to reduce inoculum buildup.
• Proper orchard hygiene, including the removal of fallen leaves.
• Application of protective fungicides during periods of high disease pressure.
• Maintaining optimal spacing between trees to improve ventilation and reduce leaf surface moisture.