The first large-scale attempt at controlling the red tide was made in the autumn of 1957. About 16 square miles stretching along 32 miles of shoreline from Anclote Key to Pass-a-grille Beach, off St. Petersburg, Florida, were dusted with copper sulfate (CuSO4·5H2O) at about 20 pounds to the acre by crop-dusting planes. The copper very quickly reduced G̲y̲m̲ṉo̲ḏi̲ṉi̲u̲m̲ ḇṟe̲v̲e̲, the red tide organisms, from several million to practically none per liter relieving the area of the respiratory irritation caused by the airborne toxin of G̲. ḇṟe̲v̲e̲. In 2 out of 5 areas the organisms rose again to concentrations lethal to fish in 10 to 14 days after dusting. This method is not recommended for general control, but will give temporary relief in local situations from the airborne toxin