Viruses are extremely small and can only be observed with an electron microscope.
Over 50% of known plant viruses are rod-shaped. The second most common structure amongst plant viruses are isometric particles.
Tobacco mosaic virus, the length is about 300-500 nm with a diameter 15-20 nm.
Tobacco necrosis virus A, diameter varies from 40-50 nm in diameter
Cocoa swollen shoot virus, genus Badnavirus [largest size is 30 nm wide and 300 nm long]
