In the world, powdery mildews fungi (PM) have been recorded to damage over 700 botanic species (Braun and Cook, 2012). Several PM species parasite on oaks Quercus sp. (Takamatsu et al., 2007) and para rubber tree Heveae brasiliensis (Limkaisang et al., 2006) such as E. alphitoides, E. quercicola, E. extensa va E. hypophylla, etc... In Vietnam, resine yield of para rubber tree could be reduced even 30 percent due to PM. This species belonging to Erysiphe genus which has some morphological characteristics including conidiophore with single chain, conidia with ellipsoid shape and size (length: width) (11w) (30-)35-42.5(-45) x 15-20(-22.5) um without fibrosine
footcell with cylindrical shape with size (length: width) (37.5-)42.5-50 x 7.5-10.0 (-11.3) um
mycelium bearing appressorium with lobellobed opposite/multilobed shapes
conidia germination with Pseudoidium type, Extensitubus sub-type. Using primer pairs, HF1/HR4 (this study), and NL 1, NLP2 (Mori et al., 2000) for cloning and sequencing ITS and 28S rRNA regions of samples PM fungi HB1-HB6 and HB1-HB2, respectively from provinces including Son La, Lai Chau, Binh Phuoc, Dong Nai, Ba Ria - Vung Tau, Dak Lak in Vietnam, obtained sequences were registed in GenBanks with accession numbers (GA.) KM260698-KM260703 for ITS and KM260680-KM260681 for 28S. Powdery mildews fungi on all samples from Vietnam belong to Erysiphe quercicola group which separates from E. alphitoides group extracted from DNA database with strong bootstrap values support 100 percent and 98.1 percent in MP phylogenie trees based on analysing ITS and 28S rRNA sequences, respectively.