var Line = "25/03/2018";
var Line2 = "13/07/2018";

var treatments = [{
        type: 'line',
                  mode: 'vertical',
                  scaleID: 'x-axis-0',
                  value: Line,
                  borderColor: '#007e24',
                  borderWidth: 4,
                  label: {
                    enabled: true,
                    content: '13/07/2018'
                  }
      },
      {
        type: 'line',
                  mode: 'vertical',
                  scaleID: 'x-axis-0',
                  value: Line2,
                  borderColor: '#000',
                  borderWidth: 4,
                  label: {
                    enabled: true,
                    content: '13/07/2018'
                  }
      }

    ];

var dates = ["01/03/2018", "01/05/2018", "09/10/2018"];
var colours= ["#000", "#000", "#fff"];

    var treatments = [{
            type: 'line',
                      mode: 'vertical',
                      scaleID: 'x-axis-0',
                      value: DYNAMIC VALUE,
                      borderColor: 'DYNAMIC VALUE',
                      borderWidth: 4,
                      label: {
                        enabled: true,
                        content: '13/07/2018'
                      }
          }

        ];