This comprehensive study aimed to investigate the causal organisms, disease incidence and pathogenicity of microorganisms affecting gerbera plants in the Dhaka zone of Bangladesh. Nine sites of Agargaon, Savar, Gazipur, and Narayanganj were surveyed to identify the diseases based on symptomological studies. Diseases caused by fungi including cercospora leaf spot (Cercospora sp.), alternaria leaf spot (Alternaria alternata), sclerotinia wilt (Sclerotinia sclerotiorum), anthracnose (Colletotrichum capsici), powdery mildew (Erysiphe sp.), blight (Curvulariageniculata), graymold (Botrytis sp.), stem rot (Fusarium oxysporum), and viral diseases such as leaf curl (Leaf curl virus) and mosaic (Mosaic virus) were identified. Among all the identified diseases, the highest disease incidence (66.67%, Gazipur) was exhibitedby alternaria leaf spot and the lowest disease incidence (5.56%, Narayanganj) was shown by graymold. The rate of reduction of plant height due to cercospora leaf spot, alternaria leaf spot, blight, anthracnose, graymold, sclerotinia wilt, stem rot, powdery mildew, mosaic, and leaf curl diseases was 28.1%, 28.42%, 12.47%, 12.69%, 28.36%, 30.67%, 19.14%, 28.08%, 12.89%, and 22.06%, respectively. The rate of reduction of other plant parts of gerbera was also recorded. To confirm pathogenicity, Curvulariageniculata, and Erysiphe sp. were tested on healthy gerbera plants following Koch’s postulates. The plants exhibited the disease symptoms of Curvulariageniculata and Erysiphe sp. after 9 and 6 days of inoculation, respectively, while the control plants remained symptom-free. Thus, the pathogenicity of Curvulariageniculata and Erysiphe sp. was confirmed.
