In the late 19th century European vineyards began dying and for a while it looked like curtains for the wine business, and then, somebody noticed that a native vine in the US seemed impervious to the disease. Why not graft this resistant rootstock to European vines? The disease was called Phylloxera and the vineyards of France were saved.
Now the selection of rootstock is an art in itself. Rootstock that is resistant to, not only Phylloxera, but nematodes, does well in sand, does well in heavy soil, vigorous, not vigorous. In our new Lafond Vineyard block of Chardonnay, that we are planting this spring, we looked for a rootstock that was vigorous – the soil is very sandy — and nematode resistant because nematodes thrive in sandy soil.
The nematode, a roundworm, found in many environments, among them vineyards, thrives in sandy soil, while Phylloxera, an insect related to aphids, does well in heavier soil. Both attack the vine by cutting off the flow of water and nutrients. In the late 1970s and 80s vineyards in Napa and Sonoma discovered that what was believed to be a Phylloxera resistant rootstock, was not. Since then most vineyards have been re-planted at great cost. Rootstock is important.
With the rootstock selected – we chose one called Freedom – the next decision is the Chardonnay clone. Here there is an even wider choice. We decided on four clones. We chose one, the Wente clone, because we grow it in another block and the wines from this clone are excellent. The other three were chosen after sampling wine from our neighbors’ vineyards, matching soil, and other factors, and then, crossing our fingers. None will be bad, or even mediocre, but will they go beyond excellence. We will see.
We went for a variety of clones for reasons of complexity. A blend of several clones can make a wine more interesting give it more depth. Each clone has its strengths. And the possibility that one clone will be the perfect marriage of climate and soil, ‘terroir’, is every winemaker’s dream.
Vines are grafted in a nursery, they can be planted that same year, they come in small planting pots with a few months root growth or they can be planted the following year with one-year root growth. The first are called green grafts, the second dormants. There are no shortcuts either way it takes four years before the first crop. We have done both, but now we use dormants exclusively. The survival rate is better and we think the cost is about equal.
Wikipedia has a good article on Phylloxera and a rather brief one on nematodes.
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