During the 2000 and 2001 growing season, the development and presence of virus
symptoms in snap bean crops increased dramatically. The symptoms were primarily caused by
cucumber mosaic virus and alfalfa mosaic virus. The viruses had large economic impacts by
reducing yields 90% or more and causing off colored, deformed and generally poor quality
beans. These viruses have been present in various weeds and crops within WI for a number of
years, but were seldom seen within snap bean and never to the extent seen in 2000 or 2001.
Invasion by the soybean aphid and its mid summer migration into snap bean vectored viruses at
high levels and subsequently led to the unprecedented yield and quality losses.