Electron microscopy of elongated particles associated with tulip mosaic

Elongated fibrous particles, 14–16 mμ in diameter and with a most frequent length of 750–775 mμ, were observed by electron microscopy of leaf-dip preparations of tulips showing streaked leaves and flower-breaking. Fibrous masses or bundles of similar particles were seen in thin sections of cells of infected petal tissue. The symptoms of this disease are identical with those described for tulip mosaic, also called tulip-breaking. Attempts to recover cucumber mosaic virus were unsuccessful. Because these elongated particles were absent in healthy tulip tissues, we believe that they may be tulip mosaic virus.