Wood eating fungal diseases and nematodes (microscopic worms) have existed in the soil of vineyards since the beginning of the vine, 1000s of years ago. In the past they lived off dead wood, today they are gaining ground and vines all over France are literally ‘being eaten alive’ and dieing. At first they become weaker and within a few months the leaves go yellow and the vines become sick, produce less and less fruit and eventually die. The pest (be it a fungus or nematode) moves to its neighbour plant to feed and survive.
Why is this happening today? After over 50 years of intensive spraying since WWII the natural defences of the vine have been destroyed (the occurrence of these wood eating fungus is lower in biodynamic soils). This is not limited to the vine but growing vines is intensive monoculture. The soil is not ‘relieved’ by crop rotation as in normal agriculture and so the effects are exacerbated. There are several reasons why this has arrived (which can be summarised as a lack of respect for the vine over decades):
- Extensive use of synthetic chemicals which stay in the soil
- Unsuitable use of fertilizer even organic
- Heavy use of machinery that compacts the soil and breaks up its structure
- “omega grafting” used for the past 25 years by nurseries, appears to be encouraging more Esca than the old way of grafting using the “greffe anglaise” or “greffe en fente”.
- Vine varieties have “degenerated” after centuries of vegetative multiplication without any sexual reproduction (in order to keep the posiitve qualities developed). Producers buy clones of the different grape varieties. There are three main clones of Merlot available for example. This lack of genetic variety makes it easy for disease to build up a resisitance. There is no renewing of the gene pool. Even “Selection massale” (where cuttings are made from ‘native’ vines developed in their own vineyards, remains a clonage on a small scale. Obviously, big scale clonage has exponentially increased the degree of genetic degeneration.
A type of lichen-like fungus lives in the roots of all healthy plants and enables it to uptake water and nutrients (they make these soluble so the plant can take them up more easily) but also important role in their resistance to disease – they protect the plants. These positive fungus are called Mychorizza and live in symbiosis with plants (they get sugars in return). They rely on a green plant and its powers of photosynthesis. Its a win-win situation.
Rhizosphere of a Plant – the Mychorizza are in fact extensions of the root tips and have a contact with the soil that is 10 times as large as the root network.
‘Living’ healthy soil (well aerated with some organic matter and worms) has a number of different mychorizza which live in the plant’s root network. This helps the plants to become;
- More tolerant to pH changes
- More resistant to attacking bacteria or fungi
- More resilient to environmental stresses such as temperature extremes including drought….very important with global warming
- More resitant to toxic elements in the soil
Older vines can share nutrients helping younger vines next to them helping them to grow stronger and more resilient quicker
When you have healthy plants next to eachother there is a network under our feet, an intercommunicating giant energy circuit.
Today wood eating fungal diseases (Maladie de Bois de la Vigne MDB) such as Esca, Dead Black Arm (DBA), Eutypiose are affecting today some 15 to 20% of France’s vineyards. They are present in all wine producing countries. In 2001 the only solution, sodium arsenite, was banned. Since no remedy has been found. There is no option today. Contaminated land is left barren for several years. Care is taken to eradicate all potential food, every small piece of vine from the soil. No-one knows how long it takes for the ‘maladie’ to die. Regular analysis of the soil takes place to check its progression.
Research is being undertaken by UMR, INRA Bordeaux Science and L’Academie de Sciences Louis Pasteur (Jura) including work on Trichoma an antigonistic fungas that could help control the outbreaks.
Today the vines of the Ugni Blanc the main grape for making Cognac is under attack with 20% vines contaminated. Henessy (LVMH) have donated 600,000€ to aid the research.