Botrytis gray mold of Lilium in Bangladesh: Diagnosis, basic study and control

Bangladesh Agricultural Research Institute (BARI) released two beautiful Lilium varieties in 2020. In the same year the farmers in Gazipur district reported a set of disease symptoms on these flowers and alerted the Plant Pathology Division of BARI. Subsequent investigation confirmed the symptoms as Botrytis gray mold (BGM), caused by Botrytis cinerea. The pathogen identity was confirmed through ITS gene sequencing. A series of in vitro and in planta experiments conducted to understand the symptoms, the optimal growth condition for the pathogen, potential resistant Lilium genotypes, effective chemical treatments and potential of biological control agents to combat the disease. B. cinerea exhibited the highest growth in V8 media (88.55 mm) at pH6 (85.32 mm) and temperature between 20 and 25 °C (89.56 mm), and pH6 (85.32 mm). Screening revealed that five oriental-originated genotypes provided lower disease incidence (31.66-41.66 %), and were categorized as moderately resistant to resistant in disease reaction. Six fungicides successfully reduced mycelial growth in vitro. Moreover, Ipridione provided the lowest % disease incidence (27.11) and % disease severity (5.33) in the in planta nethouse experiment. Therefore, this fungicide was recommended to the farmers initially. Additionally, two fungal biocontrol agents Epicoccum nigrum EJS002 and Trichoderma ThC003, demonstrated effectiveness in reducing leaf lesion size over control in a detach leaf assessment technique. In conclusion, this study presents BGM of Lilium as a farmers issue for the first time in Bangladesh. It also provides valuable insights into its management, recommending specific chemical fungicides for farmers to use, and two fungal antagonists (E. nigrum EJS002 and Trichoderma ThC003) as potential disease control agent.