Powdery mildew is a serious disease of economically important hazelnut crop in Turkey. Hazelnutproduction has been extremely affected by the disease in terms of quality and quantity. The diseaseis caused by two different fungi, namely Erysiphe corylacearum and Phyllactinia guttata. E.corylacearum has been shown to be the responsible one predominantly for the recent economicdamage. The fungi produce a mycelium network on hazelnut plants before they sporulate andvisually detected. Early detection of these pathogens is important for management as well asunderstanding their spread and epidemics. In this study, a PCR assay was developed for thedetection of both pathogens from hazelnut plant leaves by targeting their ribosomal DNA genes intheir internal transcribed spacer (ITS) regions. Two sets of specific primers were designed for thedetection of E. corylacearum and P. guttata at an early stage of infection. As a result of PCR, aspecific band of 578 bp was observed. The amplicon sequencing confirmed the presence of only E.corylacearum, but not P. guttata. Therefore, this PCR-based test can identify plants that are infectedwith powdery mildew before they show any visual signs. From there, the infected plants can betreated or removed before the fungus has a chance to produce spores that infect neighboring plants.These results would help tackle the eradication of powdery mildew.