Bordeaux mixture bôrdō´ [key], fungicide consisting of cupric sulfate and lime in water. Its fungicidal activity is associated with the slow formation of copper compounds, the ultimate toxicant being the cupric ion. It originated in France in 1885 and was widely used for spraying orchards, dusting crops, and treating seeds until c.1930. Since it was found that Bordeaux mixture frequently caused russeting of fruit, injured the leaves, and led to premature defoliation, it has been generally replaced by solutions made with powdered fixed copper. Sal soda Bordeaux, or Burgundy mixture, containing cupric sulfate and sodium carbonate (sal soda), was formerly used to spray small fruits but has been replaced by more convenient preparations. See pesticide.
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