Botrytis bunch rot and sour rot are not the same, and these clusters of white grapes demonstrate the difference between the two. The cluster at left is infected with bunch rot, and shows the telltale growth of Botrytis fungal spores (the gray, velvety fuzz). The cluster at right, on the other hand, shows the pinkish hue characteristic of white grapes infected with sour rot. (Courtesy Wendy McFadden-Smith/ OMAFRA) Sour rot can be a frustrating foe in vineyards, but after more than a decade studying it, researcher Wendy McFadden-Smith has a good idea about what causes it, what makes grapes vulnerable […]