Which one of the following is linked to the discovery of Bordeaux mixture as a popular fungicide ?

Question

$\begin {array} {1 1} (1)\;Black\: rust\: of\: wheat & \quad (2)\;Bacterial\:leaf\: blight\: of\: rice \\ (3)\;Downy\: mildew\: of\: grapes & \quad (4)\;Loose\: smut\: of \: wheat \end {array}$