Barley Yellow Dwarf Disease in the Kyiv Region of Ukraine: Survey and Pathogen Characterization

Abstract

Barley Yellow Dwarf (BYD), caused by viruses from the Tombusviridae and Solemoviridae families, poses a serious threat to wheat production worldwide. In Ukraine, a major wheat-producing region in Europe, the disease has caused growing economic losses, exacerbated by aphid vectors, susceptible cultivars, and variable environmental conditions. Despite long-term monitoring, the pathogens responsible for recent outbreaks and their molecular characteristics remain insufficiently studied, limiting the development of targeted management strategies. This study aimed to evaluate BYD incidence over 11 years (2014–2024) in the Kyiv region of Ukraine, identify the causal pathogen(s) in the 2019/2020 and 2023/2024 outbreaks, and characterize them at the molecular level. Methods. Annual field surveys were conducted on 4.5 ha of winter wheat plots, monitoring nine cultivars for disease symptoms and collecting leaf, aphid, and weed samples. Grain yield was assessed at maturity using a Sampo-130 combine on 100 m² plots with four replications. Meteorological data were obtained from the Ukrainian Hydrometeorological Center and analyzed for key phenological stages. Serological detection used a double- or triple-antibody sandwich ELISA, and molecular confirmation involved RT-PCR amplification of a 641-bp coat protein gene fragment, followed by Sanger sequencing and the maximum-likelihood phylogenetic analysis. Yield data were analyzed using ANOVA (p < 0.05). Results. Barley yellow dwarf virus-PAV was identified as the sole pathogen in symptomatic wheat, its vectoris Rhopalosiphum padi, and the alternative hosts are Arrhenatherum elatius and Echinochloa crus-galli. Phylogenetic analysis showed 92% nucleotide identity between wheat and aphid isolates, clustering with strains from Ireland, Poland, Turkey, and the Czech Republic. The grass isolate shared 85% identity and formed a separate clade with isolates from the USA, Belgium, and China. In the susceptible cultivar Poliska 90, yield losses reached 69.8% in 2020 and 29.2% in 2024, whereas the resistant standard Lisova Pisnia was minimally affected. Conclusions. Barley yellow dwarf virus-PAV is the primary pathogen causing recurrent epidemics in Ukrainian winter wheat over the 2019/2020 and 2023/2024 growing seasons. The spread of BYD is facilitated by viruliferous aphids, host susceptibility, and favorable environmental conditions.