Gerbera (Gerbera jamesonii H. Bolus ex. J.D. Hook) is one of the major cut flowers in Turkey, with approximately 114.00 ha and a production of 128 million per year. Gerbera decline was observed in several greenhouses in Izmir province of Turkey. Affected plants exhibited yellowing and wilting of leaves, growth deficiency and decline in flower quality. Infected roots and crowns rotted. A fungus-like organism was consistently isolated from necroses that appeared on roots and crowns of gerbera in Izmir in 2016. Diseased gerberas were collected from five districts where more than 90% amount of gerberas cultivating areas in Izmir. The pathogen was identified as Phytophthora cryptogea based on morphological characteristics and DNA sequence of internal transcribed spacer (ITS) region. Pathogenicity of the isolates were tested under growth chamber conditions (22-24 degrees C, 16/8h day/night) on 2-month-old gerbera 'Sky Line' seedlings. Isolates of P. cryptogea were pathogenic on gerberas that were infected soils via inoculated rice grains. After 3 weeks, root and crown rot, yellowing and wilting of leaves developed in plants that inoculated with P. cryptogea. This study demonstrated that P. cryptogea causing root and crown rot of gerbera in Izmir province in Turkey.