Convention I . H . G . C . Proceedings of the Scientific Commission

Hop downy mildew (Pseudoperonospora humuli) and hop powdery mildew (Sphaerotheca humuli) are the most important fungal plant diseases of hop (Humulus lupulus). The early detection and diagnosis of pathogens are often aggravated with symptomless before mass infection or commutation with another pathogens. Molecular analysis of internal transcribed spacer (ITS) regions of rDNA is a novel and very effective method of species determination. The specific PCR assays were developed to detect pathogens Pseudoperonospora humuli and Sphaerotheca humuli in naturally infected hop plants. Specific PCR primers combinations P1+P2 and S1+S2 amplified specific fragments from Pseudoperonospora humuli and Sphaerotheca humuli, respectively, and did not crossreact with hop DNA nor DNA from other fungi tested. PCR primers combinations R1+R2 and R3+R4 were possible to use in multiplex PCR detection of Pseudoperonospora humuli, Sphaerotheca humuli, Verticillium albo-atrum and Fusarium sambucinum. The phylogenetic relationships were inferred for 47 species of Oomycetes and 42 species of Erysiphales from nuclear rDNA (ITS1, 5.8S, ITS2). The molecular characterisation and phylogenetic analyses confirmed certainly species identification of both pathogens. These PCR assays proved to be accurate and sensitive for detection, diagnosis, classification, diseases monitoring and forecasting.