Issue link: http://read.dmtmag.com/i/267019
6 0 V I N E YA R D & W I N E RY M A N A G E M E N T | M a r - A p r 2 014 w w w. v w m m e d i a . c o m P h a e o m i n i e l l a c h l a m y d o s p o r a (Esca); Neofusicossum parvum (Botryosphaeria dieback, or Bot canker); and Phomopsis viticola (Phomopsis dieback). Annual economic yield losses in California vineyards from Euty- pa and Botryosphaeria are widely reported at 14% of the gross pro- ducer value. Shortened vine and vineyard lifespans result in eco- nomic losses with more frequent replacement costs. ood canker diseases, trunk dis- eases and Eutypa dieback are descriptions for fungal infec- tions of the permanent woody parts of a grapevine that lead to declines in vine production and health, and can lead to vine death. A major focus of a current research project is to develop new tools for early can- ker-disease detection in vineyards, and to prevent disease infection and spread in young vineyards. Canker diseases occur in grape- growing regions worldwide, but they are bigger problems in Medi- terranean climates, where the vine woody structure remains many years without freeze damage. Can- ker diseases can be caused by one or more fungal pathogens. More than 20 canker-disease fungal spe- cies are found in California; the five most common and aggressive species, and their diseases, are: Eutypa lata (Eutypa dieback); Togn- inia minima (Esca, or measles); Infection occurs primarily on pruning wounds resulting from fungal spore contact. Broken or damaged vine parts can also be infected. After wood colonization by Eutypa lata, a canker forms near the infected pruning wound. Cross sections of infected spurs, cordons or trunks show dark wedges or pie- shaped areas of rotted wood. Foliar infection symptoms can appear as stunted shoots with small, cupped, chlorotic and tattered leaves from late April into May. Flowers on these shoots do not develop clus- ters. Eutypa foliar symptoms can take a long time to develop: three to eight years after infection. Bot canker also causes wedge-shaped Researchers aim to develop new tools for early detection a n d p r e v e n t i o n New Strategies Sought for Grapevine Canker Disease Management BY TED RIEGER, SENIOR FEATURE EDITOR Common grapevine canker disease symptoms are a wedge-shaped area in a crosscut section of diseased vine wood. Photo: Ted Rieger