or

Telerik.Windows.Controls.GridViewColumn timeColumn = this.RadGridView1.Columns["subject_timestamp"];Telerik.Windows.Controls.GridView.IColumnFilterDescriptor timeFilter = timeColumn.ColumnFilterDescriptor;timeFilter.SuspendNotifications();timeFilter.FieldFilter.Filter1.Operator = Telerik.Windows.Data.FilterOperator.IsGreaterThan;timeFilter.FieldFilter.Filter1.Value = DateTime.Now.AddYears(-1).ToShortDateString();timeFilter.ResumeNotifications();public IQueryable<MyModel> Data{ get { return this.dataService.GetData(); }}<telerik:RadGridView Name="RadGridView1" GroupRenderMode="Flat" ShowInsertRow="True" CanUserInsertRows="True" CanUserFreezeColumns="False" ItemsSource="{Binding Data}" AutoGenerateColumns="False" SelectedItem="SelectedItem" ActionOnLostFocus="CommitEdit" RowIndicatorVisibility="Collapsed" ShowGroupPanel="False">