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S M Aw iT n V MT A K IN T U R E R e I ICULG In a 2009 study by Úrbez-Torres and others,6 Botryosphaeriaceae fungi were the most common fungi isolated from grapevines affected with dieback in Texas. The highlight of this study was to show that Phomopsis was demonstrated as a trunk disease pathogen able to cause cankers. All fungal species tested were the first reported in Texas. In the northeast U.S., studies published in 2013 have shown that two species of Phomopsis, and one of closely related Diaporthe eres were responsible for wood cankers and pruning wound infestations.8 Diaporthe eres has recently (2012) been shown as a grapevine trunk disease in Croatia.9 It is a similar picture in Mexico. ÚrbezTorres and others in 2008 reported two Botryosphaeria fungi as the primary cause of grapevine dieback and canker formation, and confirmed their pathogenicity.7 An Australia study published in 2010 included a survey of 73 vineyards in two states and samples taken from 2,239 grapevines.10 The most common species found was Botryosphaeriaceae, and species varied with region. There is a survey by Úrbez-Torres and others in British Columbia,11 where growers and scientists have only recently (since 2007), become concerned about trunk diseases. They surveyed young and old vineyards in 2011, using 173 vineyards, and identified trunk disease as a previously unknown problem. All vineyards sampled showed trunk disease symptoms, including both young and old vineyards. The situation regarding production of nursery vines is equally serious. The two Spaniards David Gramaje and Josep Armengol published an extensive 2011 review of trunk diseases in the propagation process.12 They conclude that fungal trunk diseases are a major cause of young vine decline worldwide, which reduces productivity and longevity. These dis- THE MOST TRUSTED eases may be called Black Foot or Petri ("Black Goo") disease, and a number of fungal species are involved. These are species of Cylindrocarpon, Ilyonectria, Phaeoachremonium, Phaeomoniella, Cadophora and Botryosphaeriaceae. Many investigations around the world have shown that the major problem is fungal infection of cuttings taken principally from diseased rootstock mother vines. Contamination spreads further during the propagation process, especially in water baths. Such infections can be avoided by using hot water treatment (HWT), as is employed by a couple of Australian nurseries. Why is it not more widely used? Nurserymen around the world are frightened of the process, but new research has produced safer protocols. There is an urgent need for more international research on HWT, so that the process may be more widely adopted. HWT and replanting of rootstock mother vines and preventing their infection will largely overcome the problem of selling trunk disease-infected vines. What can we conclude from all this? •There has been much research activity since 2005, in California and elsewhere, which demonstrates that trunk disease by Botryosphaeriaceae is a widespread, typically misdiagnosed and an unrecognized problem before recent studies listed above. • Some diseases, especially Botryosphaeria, can be virulent pathogens. They spread by infecting pruning wounds, which they do more successfully than does Eutypa. Botryosphaeriaceae is presently very widespread in Califor nia, found in around 90% of vineyards tested.1 • Worldwide, there is a serious problem with infected grapevines produced by nurseries, which causes early and enduring mortality, uneven establishment and variable vineyards. Further, infectious diseases such as Botryosphaeria dieback can infect healthy vines and the economic viability of vineyards can be threatened. "In my experience, canker diseases are "I agree that we do not have enough seldom misdiagnosed or unrecognized," information as how to prevent Bot canker says Paul Verdegaal, UC Extension farm in existing vineyards —what matters most advisor. "They are, however, sometimes to growers," says Steve Thomas, vineyard ignored for one of two reasons: either the manager at Kunde Family Estate in Ken- impacts of the disease are not fully appre- wood, Calif. "We rely on the expensive ciated or, more commonly, growers are painting of pruning cuts in 550 of our 600 uncertain as to how to best manage vine acres in Sonoma Valley. We spend infected vineyards." about $150 per acre painting cuts with paint plus a fungicide. We feel this is worth the expense to extend the life of the vineyard." My take on all of this •I can find no reference to recent extension activities on trunk diseases. There seems much less research on trunk disease than 10 years ago. I reviewed the RESOURCE FOR DEER FENCING THE INDUSTRY'S BEST DEALER PROGRAM. THE HIGHEST QUALITY DEER FENCE. www.deerbusters.com UNRULY DEER? 10 p ractic al w i ne ry & v i ne yard JANUARY 20 14 Get the Digital Editions free! Send your email address to subs@winesandvines.com.