Veraison

Veraison - Pinot Noir

The Pinot Noir grapes are starting to change colour from green to red. This is the start of the ripening process and in viticulture is called veraison.

Grape berries have two distinct growth phases. The initial phase is when the cells divide and expand and the grapes begin to swell and fill out the bunch. After veraison the acidity decreases due to degradation of Malic acid, making Tartaric acid the predominant acid. At the same time sugars (glucose and fractose) are accumulated and the volume of water entering the grapes decreases resulting in an increase in sugar concentration. The level of sugar accumulation in the berries is dependant on leaf photosynthesis which is why we could do with some more sun!

As the fruit ripens it becomes more attractive to the birds. As well as the KiteHawk and Helium Ballon we will be netting the outer rows of the vines early next week.

Leaf Pulling/Plucking

A Pinot Noir vine before leaf removal  

After leaf pulling

Leaf pulling is the removal of leaves around the grape bunches, which allows the vines to dry off much quicker after rain or heavy dew which in turn makes the vines less susceptible to the spread of fungal diseases like mildew and botrytis. It also improves the coverage of spray applications, and improves sunlight penetration which helps to ripen the fruit and improve aroma.

In Germany they remove leaves early (soon after fruit set) as they believe that this helps to thicken the berry skin making the berries more resistant to botrytis.  Leave are removed again just before veraison.

We've just started the process of leaf pulling. Hopefully it will be worth it as it's very labour intensive; each row takes about an hour which equates to more than 20 man days for the whole vineyard. Next year we will investigate buying or renting a machine to do the work!

Postscript

It seems that I have been too aggressive with my leaf pulling; it's important not to take off too many leaves as they are needed for photosynthesis. Also, not surprisingly, Alex is much faster and only takes 30 minutes/row!

Powdery Mildew, Sulphur and Compost Teas

Powdery Mildew

Sadly Powdery Mildew has arrived at the vineyard, at the moment primarily infecting some of the Pinot Noir on Block A.

Powdery Mildew survives the winter either within infected buds, which subsequently germinate to form mildewed “flag shoots”, or as tiny fruiting bodies that lodge in the bark on the vine which release new spores to infect young tissues in the spring. Leaves are highly susceptible to infection while they are expanding but become resistant soon after they’re fully expanded. Berries are highly susceptible from flowering until shortly after fruit set, but become much more resistant afterwards. Interestingly, research has shown that significant berry infection at harvest can almost always be traced back infection soon after flowering.

So far our strategy to deter fungal infections has been to use compost teas, the theory being that by populating the foliage with the good guys there will be no room for the mildews to infect the plant. Unfortunately recent weather conditions have been ideal for powdery mildew which thrives in temperatures between 15C and 25C with a high relative humidity and as a result the compost tea hasn't been fully effective.

The standard organic treatment for Powdery Mildew is Sulphur and Potassium Bicarbonate (baking powder), both of which are sprayed onto the foliage of the plant. Garlic sprays are also be used as garlic naturally contains high levels of sulphur. Rain and free moisture on the surface are also unfavourable for colonisation, sporulation and dispersal, so the sulphur and baking powder are often sprayed with high quantities of water in the morning so that the foliage takes most of the day to dry.

The problem with sulphur is that it also prevents the good bacteria and fungal content from the compost tea from doing their job; so unfortunately it's one or the other. We have decided that for the time being we cannot risk the further spread of the disease so we will be spraying the plants on Block A with sulphur and baking powder.

We will have to review our spray programme for next year; as sulphur is a preventative measure and not curative, we should really be using it from the beginning of the year if it is to be fully effective.

Organic Viticulture in the Rhinegau

Vineyards in Assmannshausen

The Rhinegau is one of the most famous and beautiful wine making areas of the world and is also a centre of competence for organic viticulture and wine making. At Geisenheim there is a grape breeding institute and research centre where organic viticulture is a compulsory subject for all of their 1000 students. In Germany there are 215 wine organic growers, farming 1,400 acres, who are members of ECOVIN, the Federal Association of Organic Viticulture which was founded in 1985. ECOVIN is the largest association of working organic wineries in the world.

Last week a group of 7 organic vineyard owners from the UK went to Rhinegau to visit the Geisenheim research centre and to gain first hand practical experience of organic viticulture in the region.

Much was learnt during the course of the 3 days we spent there and particular thanks must go to Professor Kauer at Geisenheim and vineyard owners and wine makers Michael Albrecht, Peter Asbach-Kretschmar, Axel Schmitt, Johann Schnell and Hans Lang, who made us so welcome during our trip.  Their passion for organic practices was truly inspiring and confirmed our belief that it is the basis for sustainable viticulture in the future.

Professor Kauer at the vineyard of the Research Centre at Geisenheim

Michael Albrecht in his Winery

Of course we also tasted a lot of excellent quality wine including many made from Riesling and Pinot Noir, which are the main grape varieties in the region. However we also enjoyed tastings of Sylvaner, Pinot Gris, Dornfelder and many others.

Wine Tasting with Peter Asbach-Kretschmar and Michael Albrecht