This is the third season for our Valvin Muscat grapevines in the field. We had noticed "Muscat spot" on them each year. According to the New Yours State Ag Experiment Station at Geneva Food and LIfe Sciences Bulletin 161, 2006: "Symptoms of “rupestris speckle”, an apparent physiological disorder associated with grapevines related to Vitis rupestris, are commonly seen on Valvin … [Read more...] about Muscat spot on Valvin Muscat grape