Epidemiology and Yield Loss Assessment of Banana Fusarium Wilt (Tropical Race 4) in Sindh, Pakistan

Abstract

Panama disease, caused by Fusarium oxysporum f. sp. cubense (Foc), is a globally significant soil-borne disease threatening banana production. In Pakistan, the disease was first reported in 2014–15 and has since emerged as a major constraint to banana cultivation, particularly in Sindh province. This study aimed to assess the current distribution and severity of Panama disease, estimate associated yield losses, and characterize the Foc isolates responsible for the outbreak. Field surveys were conducted across eleven major banana-growing districts in Sindh, where disease incidence was recorded based on symptomatic assessment of plants in selected orchards. Infected samples were collected and subjected to both morphological and molecular identification using race- and lineage-specific primers. The average disease incidence across surveyed areas was 17%, with a maximum of 42% recorded in Thatta district. Based on these incidence rates and national production data, yield losses attributable to Panama disease were estimated at approximately 44,150 tonnes, indicating a 20% reduction in total banana output for 2022. Morphological analysis confirmed the presence of Fusarium oxysporum, and molecular diagnostics identified 15 out of 17 isolates as Tropical Race 4 (TR4). Two isolates, however, tested negative for both Race 4 and TR4-specific primers, suggesting the possible presence of other Foc races or novel variants. The widespread use of infected suckers, flood irrigation, and poor field sanitation were identified as key factors contributing to disease dissemination. These findings underscore the urgent need for containment strategies, including resistant cultivar development, improved diagnostic surveillance, and stricter quarantine enforcement. This study provides the first comprehensive overview of the Panama disease epidemic in Pakistan and highlights the threat posed by TR4 and potentially emerging Foc variants to national banana production and food security.