A grapevine trunk cross section with trunk diseases, though the typical symptoms are barely visible. Photo: Annie Klodd The photo below shows a cross section of a Marquette grapevine trunk. Looking at this photo, would you think that there was anything wrong with it? As it turns out, this grapevine has five different trunk diseases responsible for grapevine decline including "dead arm," Esca, and Eutypa, revealed by expert laboratory analysis. Often in online resources, plant diseases are demonstrated in photos that clearly show the symptoms. This is so that farmers can accurately identify them out in the field with as little ambiguity as possible. However, sometimes diseases can be present even if the tell-tale symptoms are not yet visible, such as in this example. The Marquette grapevine pictured was not producing well in 2018 and parts of its cordons had begun to die. We were curious whether this declining grapevine was infected with grapevine trunk diseases, which...
