First report of Alternaria alternata causing postharvest fruit rot of lychee in Pakistan.
In July 2015, a survey was carried out in 30 lychee (Litchi chinensis)-growing fields of the Lahore and Multan regions of Punjab Province, Pakistan. Fully ripened fruit (lychee cv. Gola) were harvested and stored at 5±1°C for 28 days. After storage, light to dark, water-soaked lesions (2-6 mm diameter) were observed on the surface of stored fruit. Lesions gradually enlarged in size and coalesced, leading to rot of the entire fruit. In some cases, the rind of affected fruit was cracked and covered with dark mycelium. The disease prevalence was 33% in visited fields, which resulted in decreased lychee production. Based on cultural and morphological characteristics, molecular data (sequence analysis of the genomic DNA internal transcribed spacer region and endopolygalacturonase gene) and pathogenicity testing, the causal agent was identified as A. alternata. This fungus has been reported as postharvest pathogen of lychee fruit rot in Bangladesh and South Africa. This is thought to be the first report of fruit rot caused by A. alternata on lychee fruit during cold storage in Pakistan.