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2. Flavescence Dorée – what’s behind the headlines…

cite: http://blogreignac.blogspot.frThe last couple of weeks in February saw a cause célèbre, and the focus of that ’cause’ had a name – Emmanuel Giboulot.

There were also a rag-tag bunch of ‘supporters’ filling the airwaves (web-waves?) with stories pro (mainly) and against what he had done; i.e. he chose not to spray an insecticide in his vineyards. I’m absolutely convinced that Giboulot did this with the best of intentions – no insecticide had been sprayed in his domaine since the 1970s, but, he became an unwitting (I believe) standard-bearer for all sorts of green causes that may or may not have some basis in rational thought.

Whether you condone what Giboulot did, or not, should (I hope) depend on your understanding of the basic facts. My understanding was insufficient, so I approached the BIVB‘s Technical Director, Jean-Philippe Gervais to help me fill in the gaps; my thanks to him for the notes that follow.

This article focuses not on what Giboulot, and other vignerons may, or may not, have done, but rather those basic facts of the situation. Because I haven’t read much of this stuff elsewhere, in some cases, any of it, I thought that a ‘grounding’ in the issues would be as much of interest to you, as it was for me. I’ve tried to structure the info so that the various facets flow into each other, so that you may have a feel for the consequences:

In 2012, 12 hectares of vines were uprooted in Burgundy, having been infected with the malady, Flavescence Dorée. In 2013, it was just 0.2 hectares that were uprooted – though other ‘sick’ vines have been located and are now being monitored. If a vine is infected with Flavescence Dorée (FD), it has 1-3 year life expectancy – longevity is little different if it is an old or a young vine. Chardonnay, however, is more susceptible to FD than pinot noir.

The ‘organism’ that causes this sickness is called a phytoplasma, and it has long been a resident in Europe (according to DNA testing), but before 1949, in Armagnac, it had never been found in vines – only trees and flowers. In 1988 the FD was first recorded in Burgundy – in Puligny-Montrachet. North America has no phytoplasma – that will soon be relevant.

The so-called ‘vector’ for FD is the cicadelle, a flying insect that is an ‘unintentional import’ into Europe from North America. As an ‘import’ the cicadelle appears to have no predators in the (European) wild. As a ‘vector’, if a ‘clean’ cicadelle bites a ‘clean’ vine – no problem, but if a clean cicadelle bites an infected plant and afterwards bites an uninfected plant – that second plant now becomes infected – because that cicadelle is no-longer ‘clean’, it is now a carrier. You can compare this to how mosquitoes spread malaria. Because there are none of these phytoplasmas in the Americas, the cicadelle is harmless to vines in that continent (clean + clean). So phytoplasma and cicadelle together, are simply an unfortunate coincidence in Europe, very unfortunate for vines.

You would be forgiven for thinking that the spread of this ‘issue’ is very slow – starting in 1949 and only now becoming ‘news’? Largely that is put down to the fact that people sprayed pesticides throughout the 60s, 70s and onwards. In Burgundy where there is the largest concentration of organic/bio/biodynamic producers there is, interestingly, also the most ‘important’ population of cicadelle in the whole of France. If somebody at, for instance, the University of Bordeaux wants to study the cicadelle, they come to Burgundy either to do it, or to collect them. Of-course nobody is interested in researching them in the US – because it really isn’t a problem for them.

It is believed that the original contamination ‘source’ in Bourgogne was the infection of young vines in nurseries with phytoplasma from other propagated plants. It would have stopped there – those vines would have died within a couple of years of planting – but bad luck intervened, that bad luck was the cicadelle who bit into those infected ‘vine-lings’ and began the spread of the infection. This source of contamination from nurseries has now (theoretically) been eliminated by the mandatory treatment of those vinelings – they need nothing more than 45 minutes in hot water!

The remaining source of FD contamination (spread) is (believed to be) only the ‘unclean’ cicadelle. The ‘population factor’ for cicadelle is a factor of seven, i.e. year 1=1, year 2=7, year 3=49 etcetera. According to the BIVB, 2013 saw all the ‘at risk’ vineyards in Burgundy treated – for the BIVB, 2013 equals ‘year 1.’ With a combination paid, unpaid and vigneron ‘observers’, about 3,000 people now monitor the vines and the cicadelle population in Burgundy’s vineyards – this is the most of any department in France.

The previously mentioned treatments (of insecticide) in 2013 were based on the mapping of both the cicadelle populations and the incidence of the phytoplasma/FD in the vineyards:

  • Saône et Loire (Chalonnaise/Mâconnais) has lots of cicadelle and plenty of phytoplasma so there were three mandated treatments.
  • The Côte d’Or has lots of cicadelle but much less phytoplasma so there was only one mandated treatment.
  • Chablis and Grand Auxerrois also have lots of cicadelle but no recorded phytoplasm – so there were no mandated treatments.

All three regions remain under continuous assessment (by the 3,000…) whether they have phytoplasm or not. There may be some targeted treatments in 2014 in the Saône et Loire and Côte d’Or but no large-scale, mandated treatments are envisaged.

The BIVB confirm that the ‘governance’ of this project is rather complex, but that it needs ‘everybody’ around the table for discussion; including the certification bodies for organic/bio/biodynamics etcetera. It’s a matter of trying to achieve consensus without the obvious impression of a top-down, imposed strategy. So, how is their strategy supposed to work?

Having removed the source of phytoplasm from vine nurseries, it’s now necessary to remove infected plant material in the vineyards – they will anyway be dead in less than 3 years, but while they remain present, they still harbour the ability to turn clean cicadelle into phytoplasma carriers. Those cicadelle that are already carriers also need to be ‘removed’ i.e. to eliminate them with insecticide. Empirical observation indicates that cicadelle are not great ‘flyers’ so don’t spread-out very quickly. Hence, the plan to eliminate as many as possible in year 1 and thereafter concentrate on the pockets of ‘infection’ with targeted treatments, and N.B., ‘infection’ doesn’t mean cicadelle, it means ‘carrier cicadelle’. The aim isn’t to try to kill all cicadelle, as can be seen in Chablis where there are no mandated treatments, despite large populations of these insects.

Last, a few words on those treatments.

The insecticide ‘Pyrevert’, is the trade name of the product which most people used during these mandated treatments; it is certified as ‘allowed’ by all the major certification bodies, for organic/bio/biodynamic grape production. Pyrevert is a relatively broad spectrum (i.e. kills many insect types) derivative of pyrethrum, which is found naturally in chrysanthemum flowers. Essentially this compound (which has been used for centuries) is the same that you might buy in supermarkets/garden centres to ‘control’ (kill!) greenfly on your roses. There is also another potential treatment which is narrower spectrum, but ‘not allowed’ by certification bodies because it is a man-made molecule. Here, many ‘lutte raisonée’ domains have chosen to spray this latter compound as they believe it to be friendlier in the vines. ‘Natural’ has an emotive ring about it, but perspective is always helpful; arsenic is also ‘natural’ and has also been used for thousands of years!

I’ll finish by briefly touching on one aspect of the ‘debate’ which is certainly a powerful modifier of public perception – human/mammalian toxicity. It goes without saying that this material is toxic to insects, but there has been much discussion that it is also a contributor to ill-health in vineyard workers. It should be underlined that this inference has no basis in published fact, or at any rate, fact as established by any research reporting (and pyrethrum has been used since the Persians, against head-lice). The same goes for the ‘narrower spectrum’ ‘synthetic’ alternative for pyrethrum.

http://npic.orst.edu/factsheets/pyrethrins.pdf

2 responses to “2. Flavescence Dorée – what’s behind the headlines…”

  1. Jon

    Very well-researched and informative article that slices through the emotive stuff surrounding the original story.

  2. Claude Kolm

    Thanks, Bill. Very thorough and certainly different from the little bits I had read before.

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