The presence of Barley/Cereal yellow dwarf viruses among grass hosts in habitat fragments within an agricultural matrix in the Pacific Northwest

Background/Question/Methods

Barley/Cereal yellow dwarf virus (B/CYDV) cause one of the most devastating diseases of cereals worldwide. B/CYDVs are ubiquitous in Poaceae species and infect small grain crops as well as pasture, rangeland and native grasslands. In agriculture, B/CYDV cause the most damage globally in wheat, oat and barley production. Information on the occurrence of viruses in non-managed ecosystems is important in order to predict and manage disease outbreaks in agroecosystems. Insights into the dynamics of virus incidence in non-managed ecosystems can also provide an understanding of the competitive interactions between native and invasive grass species in these systems. Previous work in grasslands has shown that virus infection alters the competitive dynamics between native perennial grasses and annual exotic species. The wheat-producing region of northern Idaho and eastern Washington in the Pacific Northwest is characterized by fragmented native Palouse Prairie and conservation reserve program (CRP) habitats embedded in an agricultural matrix. These habitats harbor a diversity of Poaceae species that potentially serve as hosts of B/CYDV and/or contribute to disease dynamics in cereal production in the region. The Palouse Prairie is an endangered ecosystem, with less than 1% remaining as patches among an agricultural matrix. No studies have examined if B/CYDV is present in this ecosystem. Our main objectives were to determine in which habitats B/CYDV occurs and to examine the diversity of B/CYDV in space and time to better understand the disease dynamics of B/CYDV on the Palouse. We surveyed the diversity of Poaceae species in five Palouse Prairie remnants and six CRP fields adjacent to wheat fields. We collected tissue samples beginning in October 2010 through June 2012 (four collections) from each grass species within CRP and prairie habitats and examined for the presence of B/CYDV using a multiplexed PCR. The multiplexed PCR was designed to simultaneously detect for the presence of six species within the B/CYDV complex.  

Results/Conclusions

Our collections yielded 28 different grass species occurring among the prairie and CRP remnants sampled. The introduced, invasive species Ventenata dubia and Bromus tectorum were collected in both prairie and CRP sites. Native species collected include Pseudoroegneria spicatum, Festuca idahoensis, F. scabrella, and Poa secunda. Virus incidence was variable among the locations and Poaceae species collected. Potential implications of virus infection on disease dynamics in neighboring crops as well as competitive interactions within the prairies and CRP fragments on the Palouse will be discussed.