Issue link: https://read.dmtmag.com/i/620640
w w w. v w m m e d i a . c o m J a n - F e b 2 016 | V I N E YA R D & W I N E RY M A N A G E M E N T 3 5 + Esca can cause leaf inter- veinal chlorosis and necro- sis, black streaking and spotting of the wood, and a decline in vine vigor. + The main difference between young esca and esca is that, in young esca, the young vines show weak or even failed graft unions. + Most of the esca seen in vineyards is thought to origi- nate through infections of pruning wounds. + The esca complex tends to show some of the same symptoms in both young and mature vines, as well as symptoms unique to either young or mature vines. + Late pruning, double prun- ing, fungicides, and pruning wound sealants can help prevent esca infections. AT A GLANCE sca is a term that has been used to describe a complex of diseases and their resultant symptoms. The esca complex can be confusing, since it tends to show some of the same symp- toms in both young and mature vines. But esca also shows symptoms that are unique to either young or mature vines. What is further confusing is that some of the most obvious symptoms, the leaf symptoms in mature vines, are not always apparent in consecutive years. With the hope of clarifying some of the mysteries behind esca, which seems to be on the rise during recent years in Cali- fornia vineyards, I spoke with Dr. Kendra Baumgartner, research plant pathologist for the United States Department of Agricul- ture in the Agricultural Research Service. Her primary responsibility is to research grapevine trunk diseases including esca, but also botryosphaeria dieback, Eutypa die- back and phomopsis dieback. Her research focuses on developing practical farming practices to mitigate these diseases. I asked Baumgartner to explain the dif- ference between the terms esca and young esca. While they both are caused by the same trunk pathogens, Phaeomoni- ella chlamydospora and Phaeoacremonium minimum (also known as Togninia minima and Phaeoacremonium aleophilum), she explained that the differences between the two are "the age of the vine the disease affects and some of the symptoms. "In young and mature vines alike, these pathogens cause the same leaf symptoms (interveinal chlorosis and necrosis) and the same wood symptoms (black streaking and spot- ting)," she said. "Also, both cause a decline in vine vigor. Both can cause mild to moderate symp- toms that gradually devigo- rate the vine over time, or they can cause very severe symptoms that develop suddenly and kill the vine." I n y o u n g e s c a , t h e young vines show a dif- ferent symptom – weak or even failed graft unions – which has been referred to as "young vine decline." In Baumgartner's experi- ence, she tends to not see leaf symptoms on vines with young vine decline. young esca is particularly odd because vines that are only a few months old up to a few years old can look very badly stunted, but the leaves look green. "You may think it has something to do with the soil or too much 'tough love' after planting," she said, "but the soil analyses turn out fine, and there is no evi- dence of baby vine abuse. The characteristic leaf symptoms of esca begin as interveinal chlorosis and progress to necrosis. The Esca Disease Complex Start prevention strategies early to avoid infection SOIL & CELLAR REMI COHEN