Alternaria Leaf Blight on Gerbera: Assessment and in vitro Control in Bangladesh

Background and Objective: Alternaria leaf blight is a major constraint in Gerbera (Gerbera jamisonii) cultivation, causing significant yield losses. This study aimed to assess the incidence and intensity of the disease in Jhikargacha, Jashore, Bangladesh, and evaluate the efficacy of botanical and chemical control measures against Alternaria alternata. Materials and Methods: A survey was conducted across five farms to record disease incidence and intensity before and during the flowering stage. Pathogenicity tests confirmed A. alternata as the causal organism. In vitro assays evaluated six botanicals (Garlic, Neem, Ashoka, Turmeric, Tulsi, and Peppermint) at 10% concentration and six fungicides (Dithane M 45, Blitox 50 WP, Jazz 80 WP, Ridomil Gold MZ 68 WG, Hexagen 5 EC, and Tilt 250 EC) at 500, 1000, and 2000 ppm against mycelial growth. Data were analyzed using ANOVA in MSTAT-C 5.4, and means were compared via DMRT at p<0.05. Results: Before the flowering stage, mean disease incidence and intensity were recorded at 35.24 and 18.46%, increasing to 44.86 and 24.11% during flowering. Garlic clove extract exhibited the highest mycelial growth inhibition (97.33%), followed by Peppermint leaf extract (94.07%). Among fungicides, Tilt 250 EC completely inhibited mycelial growth at 2000 ppm, while Dithane M 45 showed 93.33% inhibition at the same concentration. Conclusion: Alternaria leaf blight is prevalent in Gerbera cultivation, with increasing severity during flowering. Garlic and Peppermint extracts, along with Tilt 250 EC and Dithane M 45, proved effective in suppressing A. alternata, suggesting their potential for integrated disease management.