Figure 1. Excessively vigorous Riesling grapevines in a modified Geneva Double Curtain planting in North Carolina. Downy mildew (Plasmopara viticola) is evident spreading through the canopy. High vigor can lead to inaccessible row middles and high disease pressure.
: Overgrowth of vines showing damage from disease.

Source: Mark Hoffmann, North Carolina State University