The Rise Of Grapevine Trunk Disease

Ξ December 21st, 2011 | → 0 Comments | ∇ A Day at a Time, Herbicides, Wine News |

Greybeard writes…
 
Vine Diseases are not my specialist subject, in fact before last week I knew practically nothing about them, but for some reason a casual reading of a blog post from Jim Budd set me off on a major tangential internet sortie.
 
Jim’s post was entitled “Bourgueil and Saint Nicolas de Bourgueil: the fight against eutypiose, BDA and esca”, and it was Bourgueil that hooked me, since I spent 10 wonderful days in that quaint Loire town in 2006 on a family holiday (which explains my fondness for Cabernet Franc). The fact that most of the piece was a transcript of a French article almost dissuaded me from continuing (I am nowhere near fluent in the language) except for an intriguing picture of a dying vine and Jim’s reference to “Fatal Wood Diseases”. I therefore clicked on the link to Vitisphere.com.
 
The post begins describing the disturbing development of ESCA, BDA (Black Dead Arm) and Eutypiose since the ban on the use of the controlling chemical Sodium Arsenite a decade ago. The accompanying picture shows a necrosis (canker) caused by Eutypiose.
The local viticultural body, FAV37 (la Fédération des Associations Viticoles d’Indre-et-Loire et de la Sarthe) completed a study in 2010 showing that in Indre-et-Loire alone damage from these diseases came to €12-14 million ($16-18 million) and are increasing their activities to dispose of the dead and diseased wood to try and prevent the spread of the disease.
 
The piece finishes stating that 30-40,000 vines were collected by a Chinon based wood company to recycle as barbeque fuel, but that this was only a small part of all the vines that actually died this year – a sobering thought.
 
So that was the story, but all it did was raise more questions than it answered; what exactly are the three diseases mentioned?; what causes them?; how prevalent are they?; Apart from a brief mention of sodium arsenite what else is being done to combat the disease other than making barbecue fuel?
The more sites I visited in trying to answer these starting questions, the more secondary questions (plus some ambiguity & contradiction) appeared, which sent me into yet more searches which eventually spat me out after 2 days with a glimmer of understanding and enough words to put together this piece – even though I may never get firsthand exposure to the topic.
 
The Diseases:
Eutypiose (Eutypiosis) is the French term for Eutypa dieback, first identified in the 1970s and since confirmed worldwide (Californian losses to the disease are estimated in excess of $260 million a year). The disease is caused by infection with the fungus Eutypa lata which results in stunted development and internal V-shaped necroses and external cankers. Leaves may show chlorosis, deformations and tattered edges.
In the 1970s the disease Dead Arm, made famous to consumers by the d’Arenberg Dead Arm Shiraz, was identified as really being two diseases, with the combined symptoms of Eutypa dieback caused by Eutypa lata and those of Excoriosis (Phomopsis Cane & Leaf Spot) caused by the different fungi Phomopsis viticola.
 
Black Dead Arm (BDA) is caused by yet another fungi, or to be accurate several species of the Botryosphaeriaceae, first described in 1974 in Tokaji, Hungary – giving the diseases alternative name of Botryosphaeria (Bot) canker. Over 12 species have been isolated from diseased vines globally and, while early research believed they were opportunistic pathogens that only caused symptoms in stressed vines, the current data suggests that certain strains are strong primary pathogens.
Symptoms include V-shaped necroses similar to those caused by Eutypa lata, brown necrosis along the length of the affected tissues. Confusingly, occasional stunted growth, leaf discolouration and damage adds to the similarity with Eutypa dieback, meaning the two diseases are often difficult to accurately diagnose.
In France the disease was also known as d’apoplexie lente (slow apoplexy) prior to its classification as BDA in the Medoc in 1999.
 
Esca (La Yesca in Spain) is another complex disease with variable symptom expression. Although first classified in Italy in 1900 it seems to have been around much longer with similar symptoms described in medieval works such as the influential Arabic agricultural tome Kitab al-Felahah by Ibn al-Awam, a 12th Century Moor from Seville, and earlier Latin and Greek texts. The name is Latin for food or bait (used by several Italian restaurants around the world including New York) and may be a reference to the fruiting bodies of the fungi responsible resembling bait lures as they sprout from the wood. A Wine Spectator article from 2008 reported that 5% of the vineyard surface area in France was affected by Esca, although later reports suggest that by 2010 this was as much as 10%.
The fungal pathogens are Phaeomoniella chlamydospora and various species of Phaeoacremonium which cause chronic symptoms of stunted growth, shoot tip dieback and internal wood decay of the trunk and larger branches. Leaf necrosis results in a “tiger stripe” pattern while berries show dark spots or “measles”, leading to the disease’s alternative name of Black Measles.
 
Primary symptoms predispose the vines to wood (white) rot caused by higher fungi such as Fomitiporia punctata, Fomitiporia mediterranea and Stereum hirsutum.
 
Esca affected vines may show chronic symptoms one year and the next appear perfectly normal, but the disease will reappear, each time causing an overall decline.
Eventually an acute form of the disease called vine apoplexy occurs, typically in mid-summer when rainfall is followed by hot, dry weather, where rapid withering of apparently healthy leaves and the death of vine organs, including grape clusters, happens in only a few days – the vine usually dies in the same year.
 
The main feature in common with all these diseases is that they affect vines at least eight years old or that may have been subjected to stress. It is clear from reading the reports and research papers that there isn’t always a clear diagnosis because of the similarities in symptoms; V-shaped necroses; longitudinal brown streaking in the stems; leaf chlorosis and patchy discolouration; stunted shoot growth; external cankers. In the absence of one exclusive diagnostic indicator much of the disease reported in the vineyards is probably a combination of two or all of the above.
 
It is also worth mentioning Petri Syndrome, named for Italian Lionello Petri who first published the symptoms in 1912. Also known as Young Vine Decline (Young Esca) the primary infectors of Ecsa, Phaeomoniella chlamydospora, Phaeoacremonium inflatipes and Phaeoacremonium aleophilum come together to cause disease in younger vines of 2 or 3 years. The disease stunts growth and leads to tissue decay with leaf chlorosis and necrosis. Internally, black spots or streaks are seen in the xylem tissues and the sap of infected plants can turn dark brown or black, giving the alternate disease name Black Goo.
Although common around the world this disease has been heavily researched in California since the late 1990s due to the high economic impact and the realization that infected nursery stock was the main source of diseased vines – vines pulled up for whatever reason were being replanted with plants already inoculated with the causes of the disease.
 
It would be easy to continue veering off into new areas by including other diseases such as Syrah Decline, Phomopsis or Black Foot, however the causes and mechanisms of these diseases are different or, in the case of Syrah Decline, still not fully understood, so we’ll put them to one side, at least until the end.
 
The Causes:
The key pathogens described above are all species of Ascomycetes (sac) fungi which produce spores in sacs (asci) which develop until the pressure within the asci shoots the spores out. Direct spore dispersal is up to 30cm but they travel further due to rain splash and wind – Eutypa ascospores are known to be able to travel as far as 30 miles (50km).
The exceptions are the Basidiomycete (higher) fungi such as Fomitiporia punctata, Fomitiporia mediterranea and Stereum hirsutum involved in Ecsa white rot, arguably a secondary symptom of the chronic form of the disease.
 
With BDA, Ecsa and Eutypa dieback fungal spores colonise the vine through open wood vessels, the result of pruning, frost, mechanical or graft wounds – although an Australian study shows that soil-borne infection should not be ignored. The spores develop, invading the xylem vessels where fungal growth results in the interruption of sap-flow which may induce a host defense reaction, resulting in further blockage. Wood necrosis and rot impairs the flow of nutrients leading to vine decline and slow death, while fungal phytotoxins weaken the vine causing associated symptoms.
 
Petri disease is more likely due to nursery vines infected by the fungi prior to planting, as opposed to infection through wounds, but the effects are similar.
 
Disease Management:
There is no reliable means of eradicating a pathogenic fungus once it becomes established within a vine, so removal of diseased wood or the entire plant is necessary (remedial surgery with disposal or burning of the wood debris). The best control is to protect vines from infection in the first place, but this can be challenging since the fungi are common in nature and considering the number of wounds made on each grapevine in a year with the extended period of wound susceptibility (which, for E. lata, is up to 7 weeks from pruning and greatest in early winter).
By timing any pruning as late as possible in the winter/early spring (Feb/Mar in the Northern Hemisphere) sap is flowing more freely which helps with wound healing. Spore release from infected vines is closely correlated with rainfall so new pruning should be avoided until at least 36 hours afterwards. Prof. Doug Gruber of UC Davis has championed a double-pruning technique where initial mechanically pruning leaves long spurs in early winter followed by hand-pruning to short spurs in late winter.
Application of fungicidal wound protectants in spray, paint or paste form should prevent fungal access through pruning wounds. Although spray-on liquid formulations are easily washed off with rainfall they are more feasible in large vineyards since application of paint or paste is labour intensive and only economically viable for high-value vineyards. However, which chemicals to use is the subject of intense research and contentious debate.
 
A 2009 study showed that Topsin M, aka thiophanate-methyl, was the best overall product across the Ascomycetes – yet a mixture of active ingredients is more likely to handle the spectrum of different fungi found in the vineyard.
 
Different cocktails reported include;
MBC fungicide (Benomyl, Carbendazim, Topsin M) & chlorobutinol
Biopaste (boric acid), Garrison® (cyproconazole and iodocarb) and Topsin M
Carbendazim & prochloraz (-manganese)
ATCS® acrylic paint (alone or mixed with Bavistin® or boric acid)
 
The biggest likely problem is that many of these fungicidal chemicals are likely to be removed from the market due to environmental and human health concerns, as happened with Sodium Arsenite (the only product that kept all main disease symptoms in check). This carcinogen was banned in Europe in 1991 (with extensions for Spain, France and Portugal until 2003), a fact that French viticulturalists claim is the direct cause of the relentless increase in Grapevine Trunk Disease over the last decade and has some calling for its re-introduction.
 
In reality biological & ecological control methods may be the only long term options available to growers, something which is starting to become understood.
Biological control agents include the fungi Trichoderma and Fusarium lateritium and the bacteria Bacillus subtilis, which have been shown to control infection by E. lata in trials, although results were variable. Researchers are also looking at garlic extracts and lactoferrin as wound protectants.
Biological control agents available today are based on Trichoderma species: BioTricho®, Eco-77® (both based on single strains of Trichoderma harzianum) & Vinevax®™ which is based on a mixture of five strains of T. harzianum and T. atroviride. Another agent, Trichodex® (Trichoderma harzianum T39) is also used as a treatment to prevent Botrytis cinerea (grey rot).
 
Some strains of Trichoderma work better than others, and are more effective on some varieties, such as Chenin Blanc, compared to others, such as Cabernet Sauvignon & Sauvignon Blanc. This may be why the French report poor results with Trichoderma as both these grapes seem more susceptible to Esca, BDA and Eutypa dieback (with Merlot and Semillon less so) and may be why Esca is especially prolific in southwest France and the Loire.
 
For Petri Syndrome then treatment to account for possible nursery stock infection is advised. Hot Water Treatment (HWT) at 50°C (122°F) for 30 minutes & then cooling to 2-3°C (36-37°F) for rootstock and scion wood is effective in controlling Phaeomoniella. This is similar to the method oif controlling Black foot Disease.
 
Also I came across tales of more organic remedies that are worth recounting. The first was from a Loire grower who uses companion plants (wild leek, Allium ampeloprasum) to “re-mycorhize the under-soil” which he believes has been sterilised by over use of the weed killer Roundup. In the Wine Terroirs article “Experimental cure of Esca in the Loire” the grower, Didier Barrouillet, claims he has seen vines recovering from esca.
In the same vein the 7th International Workshop on Grapevine Trunk Diseases, held in Chile last year, reported some success using soil bio-fumigation with mustard (Brassica juncea). Although used here for Black Foot Disease research the idea of bio-fumigation, using companion crops or “green manure” from Brassica species looks to be bearing fruit (!).
 
Discussion:
Those last two topics brings home the message to me that viticulture at its simplest level is only agriculture, and growing anything in the soil requires a healthy respect for that soil and the complex eco-system it harbours – something that the ever increasing use of pesticides, fungicides and herbicides can only disrupt.
 
The pathogens and symptoms of Grapevine Trunk Diseases mirror this, it would be wrong to fixate on a single cause or cure when they are a complex interaction of numerous fungi acting on genetically distinct sets of vines. A vine can, and probably does, become infected by multiple pathogens many times and while susceptibility to the effects of BDA, Ecsa and Eutypa dieback varies between grape varieties there is no sub-species of Vitis vinifera that is immune.
 
I should also reiterate that during my time reading and re-reading the different papers and presentations I encountered repeated ambiguity & contradiction both on disease naming, symptoms and causes. I endeavoured to filter through the pages to ensure as much consistency as possible, but I have no doubt that the current view of these diseases is still incomplete with more interactions awaiting to be discovered. Syrah Decline is a case in point – but I’m not going to go down that tangent just yet!
 
Slainte!
 
Greybeard
 
Additional reading:
Grapevine Trunk Diseases in California and Control Strategies (UCD Presentation)
 
Emerging diseases of vine in the central part of Spain, Vicente González and María Luisa Tello, of the Madrid Institute for research and Rural Development, agriculture and food (Imidra)
 
Abstracts from the International Workshop on Grapevine Trunk Diseases (next in Valencia, Spain, 18-21 June 2012)
 

 

Greybeard’s Corner Winter’s Hold 2011

Ξ December 11th, 2011 | → 0 Comments | ∇ Greybeard's Corner |

The year is winding its way towards the Christmas and in the northern reaches of England winter’s icy touches are already starting to be felt, but as Europe and America’s wine now sits in tank and barrel there’s still plenty of news and views to look at in the wine world.
 
Towards the end of November a controlled burn of bush in Western Australia’s Leeuwin-Naturaliste National Park suddenly became uncontrolled and advanced on the Margaret River area. The enquiry into the fires has just begun in Australia and, while there was understandable concern in the initial reporting on how this may affect vineyards and wineries in the region, in the end the damage was contained mainly within the National Park and only a few hectares of vineyard were “scorched or singed” as detailed in the recent Margaret River Wine Industry Association media release.
 
Also at the end of November Tim Atkin penned a thought-provoking piece on his website entitled “Who pays wine critics?”. Although a good article in its own right he briefly mentioned the controversy surrounding Jay Miller’s $15,000 lecture fee during a Spanish tour, broken by Jim Budd on his blog in August. That story resurfaced and then exploded a few days later into what is now being called by some as Murciagate, by others as Campogate (after Pancho Campo, the Spanish MW with his own history of controversy, who many view as being more deserving of the criticism) when it was announced that Miller was leaving the Wine Advocate. It has since become clear that the retirement had been planned for many months but the badly judged timing of the announcement has just re-fuelled the controversy – go to Jim’s Loire to see a whole series of posts on this ongoing saga. It should also be pointed out that Miller’s palate was not always appreciated and that his departure has been regarded as a positive step by some.
As for the Wine Advocate, on the back of Robert Parker’s frank review of his reputation at Wine Future Hong Kong from early November, Neil Martin replaces Miller’s Spanish and South American tasting roles, while David Schildknecht covers Washington and Oregon, bringing an end to a hectic year at the office for Robert Parker which began with Antonio Galloni taking over California duties from man himself.
 
Elsewhere in the world and South Africa producers are looking to ensure the future quality of Cap Classique Sparkling wines by formalising a new quality charter with lees ageing guidelines and introduction of “Superieur” for top examples- funny how they like the French terminology! Meanwhile Swiss researchers at the Ecole Polytechnique Federale de Lausanne have dissected what every wine lover does without thinking – swirling the wine in the glass to release the aromas – with their detailed investigations of orbital agitation and wave dynamics. It seems that this type of fluid shaking is critical in large scale cell culture bioreactors so the research isn’t as daft as it first sounded!
 
Over here in the UK and the newly resurrected Oddbins (albeit trimmed down with less National coverage than before) is courting media attention with innovative consumer events and marketing. The Drinks Business reported on the revamp to their wines. I, like many, wish this new Oddbins well although a lot of UK consumers still associate the it with the business that closed earlier in the year, even though the name and most of the remaining stores were completely bought out by Raj Chatha’s European Food Brokers (EFB) Group who have no links to the previous disgraced administration (run by Simon Baile). It would also appear that Baile’s own venture, ex-Cellars, is not doing so well either, with Jim Budd’s recent posting showing a close-down of at least two of the stores it bought on Oddbins deathbed.
 
On a lighter note it seems that twice as many UK consumers are happy with wines under screwcap compared to 8 years ago, according to a Wine Intelligence press release which goes on to confirm that natural cork is still the preferred closure. The report summary doesn’t mention the figures for that abomination that is the plastic cork.
 
As for myself, recent weeks have been relatively kind. Two local retailers have held comprehensive supplier tastings; first Carruthers and Kent with their 1st Annual Wine Fair and then Morpeth store Bin21 with a Remembrance Day event which, when combined, gave me over 120 tasting notes to work through. I also feel like I’ve been stalking Marta Mateus of MartaVine as we’ve now met up at both of those tastings plus the Durham Food Festival, Living North Christmas Fair and Hexham Christmas Fair! With the Festive Season upon us it’s never a bad idea to know a Portuguese Wine merchant and her Lágrima white Port from Quinta do Portal will definitely be appreciated over the holiday period.
As for the NEWTS then the last two meetings have been very heavy on the reds beginning with Grenache blends, where France went up against Australia in a closely matched and very enjoyable evening which saw the extracted yet elegant & complex John Duval 2007 Plexus come out as overall favourite and the meaty yet subtle Domaine De la Janasse 2004 Terres d’Argile Cotes du Rhone Villages taking best QPR at £12.95. The next tasting was a Bordeaux blends theme, with wines sourced from Majestic, which saw three French wines (including two Pauillacs) up against a selection of Old and New World. France fared less well here, with Spain and South Africa showing more character at the price points, and Australia’s Petaluma taking the group vote with the spicy, rich and smooth 2007 Coonawarra Red.
 
The first Christmas event of 2011 was also a NEWTS affair with the usual BYO dinner at the Newcastle College Chef’s Academy restaurant, where some delicious food was matched by equally delicious wines from the Society members. At our table a crisp Frédéric Mochel 2008 Cuvée Henriette Alsace Riesling was alongside a rich, oaky Catena Alta 2008 Chardonnay from Mendoza; the young and fruity Domaine de la Janasse 2005 Terres d’Argile Cotes du Rhone Villages contrasted to the aged, chocolate tannins of the Barossa Valley Estate 1996 E&E Black Pepper Shiraz; and the smooth, raisined Terre di Zagara 2004 Passito di Pantelleria offset the sharply acidic but immensely sweet Magnotta 2006 Vidal Canadian Ice Wine.
Of the 5 or 6 such Chef’s Academy evenings we’ve had with NEWTS this was the by far the best by for the quality of the food and the wine, not to mention some intelligent conversation along the way.
 
At home and with the last 15 wines I’ve bought recently my shadowing of Marta Mateus shows, with 4 from Portugal – a still white and red plus White & Tawny Ports. Another 4 bottles hail from France; a Provence Roussane, a Mâcon-Villages and a Touraine Sauvignon Blanc for the whites; a Crozes-Hermitage for the reds. The remaining 7 are scattered around the world – Spain, Italy, Austria, Australia and New Zealand – including an intriguing Piave Raboso from the Veneto, a Wagram Grüner Veltliner and a Kiwi Gewürztraminer.
 
This compares to the 16 wines which were opened in the equivalent time period, predominantly from France (6) and Italy (5) with the remaining 5 from the USA, Canada, Chile and Australia, yet only 4 stood out from the crowd; 2 French whites and 2 reds, one each from California and Australia.
The first white was the Domaine de Palejay 2008 Le Sablet Roussanne, a creamy wine with aspects of sweet melon, a full, rich texture and a honeyed finish. The second was the Couly-Dutheil Blanc de Franc, Cabernet Franc but made in a white style. This curiosity had a slight hint of peach colour in the glass and was richly flavoured with floral and grapefruit notes, a touch of honey for good measure.
For red the Ravenswood Lodi 2006 Old Vine Zinfandel punched well above its £8 price tag with a meaty nose with concentrated plum fruit and oak, fine grain tannins and warming finish. I originally bought this more than 2 years ago but deliberately kept hold of it as I’d previously had the ’03 of the same wine with 5-6 years bottle age and it was delicious. With the ’06 has proving to be same I think it’s time to but the ’09 for drinking sometime around 2015!
The last red was another with some age on it, Tim Adams 2004 The Fergus Grenache which I’ve been sitting on for nearly 5 years. This was smooth with a little liquorice and cherry fruit, gentle acidity and tannins – a joy to drink and a beautiful example of patience amply rewarded.
 
With more whites bought and more reds opened there was a slight shift in the overall colour of my cellar, which now has 28% white, 53% red and the remaining 19% a selection of Rosé, Sparkling, Sweet and Fortified. Of course whites get the fastest turnover, typically within 6 months of purchase while it is extremely rare for me to open a red so soon after I’ve got it home.
 
That’s another Greybeard’s Corner review over, much like the year. Like a lot of you I’m about to enter into this food and wine fest that is Christmas, so I’ll hopefully see you on the other side in 2012.
 
Slainte!
 
Greybeard

 

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