Three digoxigenin-labeled cDNA probes complementary to the coat protein (CP) and read-through protein gene sequences of Barley yellow dwarf virus - one each for three species, namely BYDV-GAV, GPV, and PAV - were synthesized for developing a specific and sensitive dot-blot hybridization detection assay for total RNA extracts from field-infected wheat plants. The sensitivity limit for BYDV-GAV, GPV, and PAV probes corresponded to 25microg, 31.25microg, and 62.5microg tissue/spot, respectively. The frequencies for each of the three species determined that BYDV-GAV was the most prevalent in 269 wheat samples collected from 5 agro-ecological areas in China during 2004-2006. The high sensitivity and reliability of the molecular hybridization assay described introduce an important alternative to serological methods for detecting BYDV. This is especially important in less developed countries like China, where appropriate antibodies for BYDV are not available.