Siam tulip (Curcuma alismatifolia) has become an important crop for breeding new varieties owing to its high economic value as a tropical ornamental. In September 2017, C. alismatifolia potted plants, originally from Alachua, FL, were submitted to the Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville, FL, for identification. The plants exhibited petal and bract necrosis. Initial serological testing for the presence of cucumber mosaic virus (CMV) using ELISA yielded positive results. To confirm pathogen identification, a two-step quantitative reverse transcription PCR, using primers targeting CMV-specific coat protein (amplicon of ∼450 bp), was performed. The PCR product, GenBank accession MG652768, had 99% nucleotide identity with CMV isolates in GenBank. Although all the tissues tested positive for CMV, it is unknown whether the necrotic symptoms were solely owing to CMV infection. CMV is known to infect a wide variety of plants in the ginger family, but to our knowledge, this is the first report of CMV in C. alismatifolia.