The American scientist Albert Julius Winkler (1894-1989) was one of the most important pioneers in US viticulture. At the University of California in Davis, together with the oenologist Maynard A. Amerine (1911-1998), he developed the Degree-Days system, which divided California into five climate zones and was introduced in 1944. He wrote the book "General Viticulture", which was first published in 1962. In a later edition (1974), he propagated the use of the notorious rootstock vine AxR 1, whose lack of resistance to phylloxera led to severe damage in Californian vineyards from the 1980s onwards. See also under temperature totals.
Portrait: UC Davis - Viticulture & Enology
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