$(document).ready(function() 
    { 
       if ( $("#sortTable tbody tr").length){ 
            $("#sortTable").tablesorter({
                widgets: ['zebra'],
                widgetZebra: { css: ['rowColor2','rowColor1'] },
                sortList: [[1,1]],
                headers: { 3: {sorter: false}}
            });
       } 
    } 
);