Is Clover Yellow Mosaic Virus a New Danger?
Viruses are often unrecognized members of the large group of plant pathogens that infect alfalfa and clover. One of the most common pathogens in alfalfa is alfalfa mosaic virus (AMV). This virus is widespread in Wisconsin alfalfa fields. Fortunately, it rarely seems to cause any serious problems for alfalfa or red clover, but commonly infects plants without causing any obvious symptoms, damage, or yield loss. Another virus, clover yellow mosaic virus, can act quite differently than AMV and can be very damaging to red clover. Clover yellow mosaic virus (CYMV) has recently been associated with severe damage to red clover in Wisconsin. Typical symptoms are a mosaic pattern and brown streaks on infected leaves (10). Recent studies by C. Grau and A. Mondjana (personal communication) in the Department of Plant Pathology at UW- Madison suggest this is a widespread virus that can be quite destructive and cause summer decline to red clover. It also infects alfalfa and pea, but has not been repo
