Abstract: Jabon (Anthocephalus cadamba (Roxb.) Miq.), also known as kadam, is among fast-growing tree species and has been considered as one of the promising plantation commodities. This study aimed to investigate the disease incidence and disease severity of jabon dieback in seedling as affected by pH and shaking intensity of Botryodiplodia sp. medium. Results revealed that the growth of the fungi was inhibited at pH 2 as shown by the diameter of colony formed and the much lower biomass as compared to control. Shaking intensity at 50 rpm showed the highest mycelial biomass of Botryodiplodia sp., followed by that of 100, 150 and 0 rpm. The dieback disease of jabon seedlings at all ages (3-5 months) only occurred in the treatment with inoculation with Botryodiplodia sp., fungal pathogen while the control treatment (no inoculation) did not show any symptom of the disease. The severity of dieback disease on jabon seedling was highest at 3 months old and less at other ages.