Black Spot Disease of Papaya
Initially, scattered tan spots, sometimes with a yellow halo, appear on lower leaves. On the underside of the leaves, these spots later enlarge and develop into black, raised, powdery pustules of up to 4 mm in diameter. At later stages of the disease, the lesions become necrotic and can cover large parts of the leaf. In heavy infections or co-infections with other fungal pathogens, diseased leaves can shed, leading to loss of vigor in affected trees. Shallow, light brown, irregular lesions with black fungal specks on their center are also visible on diseased fruit, although in a lesser measure than on leaves. Premature drop can occur when fruits are infected at early development stages. Despite the lesions, fruit flesh does show no signs of rotting.
The symptoms are caused by the fungus Asperisporium caricae. It is mainly present in Central America and the west parts of South-America as well as East-Africa. Both leaves and fruits can be affected and symptoms vary slightly depending on crop variety and environmental conditions. The disease is more intense on the lower leaves, and under periods of wet humid weather. Papaya is the only known host of this pathogen and normally it has a minor impact because the symptoms on fruits usually remain superficial. However, the disease can cause a reduction in fruit quality.
No alternative treatment against Asperisporium caricae has been discovered so far. Please get in touch with us in case you know of something that might help to fight this disease. Looking forward to hearing from you.
Always considere an integrated approach with preventive measures together with biological treatments if avvailable. Spraying with foliar fungicides such as dithiocarbamates can be effective in cases of heavy infestations.