Strawberry virus diseases were monitored using a leaf graft bioassay in 17 cultivars of strawberry Fragaria ananassa Duchesne in the Czech Republic. Fragaria vesca indicator clones revealed after grafting several symptoms of strawberry mottle, crinkle, vein banding, and mild yellow edge as well as of mixed virus infections. Isometric virus-like particles (VLPs) ranging from 21 to 50 nm in diameter and flexuous filamentous VLPs (12 by 600-1400 nm) were observed by electron microscopy in negatively stained crude sap preparations. Our results confirmed the complexity of virus diseases of the strawberry and represent the first report on the detection of strawberry mild yellow edge disease (SMYED) and of filamentous particles in this crop in the Czech Republic.