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Château Rouquette
June 2007 News: Managing the Vineyard: "Lutte Raisonnée"
Another Difficult Year!
2007 has probably been the most difficult beginning to the growing season since we bought the property ten years ago. The hot April pushed the vines two weeks ahead of their normal development. May started cold but the weather has increasingly been wet and humid – classic mildew weather! Continual rain has made it difficult to spray in the vineyard.
The Four Main Ways to Run a Vineyard
There
are four main systems used to manage vineyards: traditional, organic, biodynamic
and lutte raisonnée. When we bought Rouquette in 1997 it was managed
using a traditional system: during the growing season the vineyard was sprayed
on a regular basis. We soon switched to lutte raisonnée, where we only
spray when necessary (more on this later).
There are three problems with organic management. Firstly, it is not unusual to lose half one’s crop because one couldn’t spray against a disease. Secondly, the only spraying allowed, of copper sulphate, leaves residues, which appear in the wine – the EEC has been talking of legislating to limit this. Thirdly, we are in an area where by law we have to spray against flavesence dorée: a phylloxera-type desease, which can completely destroy a vineyard. This means that we cannot be organic, even if we wanted to go down that road.
Biodynamic goes a stage further than organic. Whilst the logic for limiting chemicals and working according to the moons’ phases can be understood logically, some of the preparations that are used, require an almost religious leap of faith. Filling a sheep’s skull with oak bark in the Autumn, burying it in sludge and digging it out in Spring when Mercury is in front of Aries, to add to the compost, is a complicated way to add calcium to the soil. However, having said that, there are some excellent wines made biodynamically and there seems to be some evidence that it is effective. An interesting area!
Lutte Raisonnée
This is known as “Integrated Pest Management” in the US. It uses some of the ideas from organic but without the regulatory constraints that organic requires. It applies scientific ideas on many fronts to minimize the use of chemicals.
For example, we used to spray against mildew on a regular basis. We now get a weekly, six page fax from our vineyard consultant, Cecile Dulimbert, which is supplemented by special alerts. Amongst other things this will warn us when there is a risk of mildew. This uses research that indicates that mildew only starts after 170º degree days (when the temperature is over 8º on a cumulative basis), after 5 hours of rain with a minimum of 10 mm and a temperature of more than 11º. We have four weather stations round us, which transmit continually by wireless. The data from the weather stations is input into the algorithm, which predicts the mildew risk and we can target the amount and timing of our spraying. Similar models exist for other diseases.
We are visited once a week to check the vineyard. This is to monitor activity in the vineyard such as the number of small red spiders. These can breed rapidly and feed on the vine leaves, which turn yellow and die. If we find the spider population increasing we can spray. However, there is a better long term solution. The spiders are eaten by ladybirds, so we try and encourage the ladybirds, in order to establish an ecological balance in the vineyard.
These are just two examples of how lutte raisonnée works in practice. It requires continued access to the research that is being done in this area as well as the practical implementation on the ground.
Lutte raisonnée suits our objective of reducing the use of chemicals where ever we can but in an intelligent way. For example, when we started at Rouquette we used to add sulphur to the wine that was being stored in vats on a regular basis – this stops oxidation and prevents the wine spoiling. We now carry out regular analysis of the wine to see if the sulphur is necessary. The result is that the level of sulphur in our wine is below the limits for organic wines.
Vineyard management is a rapidly evolving subject which is critical to the quality of the wine. We are always open to new ideas to experiment with. It is even possible that if you visit us at night in the Autumn, when there is full moon, you may find us sneaking out the back door with a sheep’s horn full of bark!
Michael Banton
15th June 2007