Dr. Kendra Baumgartner, a USDA ARS research plant pathologist reviews the most common trunk diseases associated with pruning wounds.
Dieback Trunk Diseases
These diseases cause shoots to grow out stunted from a spur or grow out and then dieback during the season. Dieback trunk diseases include:
- Botryosphaeria dieback (also called Bot canker) causes dieback or stunting of spurs, cordons, and canes. Leaves and shoots coming from the infected spur or cane wilt and die back during the growing season.
- Phomopsis dieback (also called Phomopsis cane and leaf spot) pathogens attack green tissue including leaves, fruit and rachis. This foliar disease is spread during spring rains. It overwinters at the base of the shoot or on old wood causing a black alligator skin pattern or blotchy patches on the base of one-year-old canes.
- Eutypa dieback causes stunted growth with tiny leaves and short shoots along with deformed leaves that are elongate, cup-shaped, and yellow with tiny internodes in a zigzag pattern.
Non-Dieback Trunk Diseases
Esca (also known as measles or black measles) does not kill off spur positions like the other trunk diseases but instead it impacts the fruit quality and causes the fruit to fail to ripen properly. Vines may have normal yields and be vigorous, but symptoms will show on fruit and leaves. Visual symptoms include:
- Black spots on fruit and leaves (measles)
- Tiger striping on leaves
- Leaf scorching and discoloration
- Symptoms are usually on individual shoots or all shoots coming out of one side of a vine
To learn more about how grapevine trunk disease pathogens spread, how to prevent them, and more check out www.vineyardundergroundpodcast.com/vu012
