First report of Wheat spindle streak mosaic virus on wheat in Croatia.
Wheat spindle streak mosaic virus (WSSMV; genus Bymovirus, family Potyviridae), transmitted by plasmodiophorid Polymyxa graminis, is one of the most important wheat viruses that cause significant yield losses. In March 2013, irregularly distributed, light green to yellow, circular patches in a wheat crop characteristic of soilborne viruses were observed in one local winter wheat (Triticum aestivum) cultivar Super Zbreve˜itarka in the Karanac locality (Baranja Country, Croatia). Initial symptoms included light green to yellow dashes, mottling, and chlorotic, spindle-shaped streaks with green centre on the leaves, which became yellow and eventually necrotic. Affected plants were stunted, with dark brown, slightly swollen, and enlarged roots. The long period of wet and cool spring weather most likely favoured disease development and severe symptoms were visible by the end of vegetation with estimated incidence of 40%. Based on the results of DAS-ELISA tests, reverse transcription-polymerase chain reaction assays and analyses of the nucleotide sequences, the causal agent was confirmed as WSSMV. This is thought to be the first report of WSSMV occurrence on wheat in Croatia.