diff --git a/manager/orchestrator/replicated/task_reaper_test.go b/manager/orchestrator/replicated/task_reaper_test.go
index f92831a582..6df4655e9e 100644
--- a/manager/orchestrator/replicated/task_reaper_test.go
+++ b/manager/orchestrator/replicated/task_reaper_test.go
@@ -493,11 +493,9 @@ func TestServiceRemoveDeadTasks(t *testing.T) {
 
 	// Set both task states to RUNNING.
 	updatedTask1 := observedTask1.Copy()
-	updatedTask1.DesiredState = api.TaskStateRunning
 	updatedTask1.Status.State = api.TaskStateRunning
 	updatedTask1.ServiceAnnotations = api.Annotations{Name: "original"}
 	updatedTask2 := observedTask2.Copy()
-	updatedTask2.DesiredState = api.TaskStateRunning
 	updatedTask2.Status.State = api.TaskStateRunning
 	updatedTask2.ServiceAnnotations = api.Annotations{Name: "original"}
 	err = s.Update(func(tx store.Tx) error {
@@ -569,3 +567,125 @@ func TestServiceRemoveDeadTasks(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Len(t, foundTasks, 0)
 }
+
+// TestServiceRemoveDeadTasks tests removal of
+// tasks in state < TaskStateAssigned.
+func TestServiceRemoveUnassignedTasks(t *testing.T) {
+	ctx := context.Background()
+	s := store.NewMemoryStore(nil)
+	assert.NotNil(t, s)
+	defer s.Close()
+
+	assert.NoError(t, s.Update(func(tx store.Tx) error {
+		store.CreateCluster(tx, &api.Cluster{
+			ID: identity.NewID(),
+			Spec: api.ClusterSpec{
+				Annotations: api.Annotations{
+					Name: store.DefaultClusterName,
+				},
+				Orchestration: api.OrchestrationConfig{
+					// set TaskHistoryRetentionLimit to a negative value, so
+					// that tasks are cleaned up right away.
+					TaskHistoryRetentionLimit: 1,
+				},
+			},
+		})
+		return nil
+	}))
+
+	taskReaper := taskreaper.New(s)
+	defer taskReaper.Stop()
+	orchestrator := NewReplicatedOrchestrator(s)
+	defer orchestrator.Stop()
+
+	watch, cancel := state.Watch(s.WatchQueue() /*api.EventCreateTask{}, api.EventUpdateTask{}*/)
+	defer cancel()
+
+	service1 := &api.Service{
+		ID: "id1",
+		Spec: api.ServiceSpec{
+			Annotations: api.Annotations{
+				Name: "name1",
+			},
+			Mode: &api.ServiceSpec_Replicated{
+				Replicated: &api.ReplicatedService{
+					Replicas: 1,
+				},
+			},
+			Task: api.TaskSpec{
+				Restart: &api.RestartPolicy{
+					// Turn off restart to get an accurate count on tasks.
+					Condition: api.RestartOnNone,
+					Delay:     gogotypes.DurationProto(0),
+				},
+			},
+		},
+	}
+
+	// Create a service with one replica specified before the orchestrator is
+	// started. This should result in two tasks when the orchestrator
+	// starts up.
+	err := s.Update(func(tx store.Tx) error {
+		assert.NoError(t, store.CreateService(tx, service1))
+		return nil
+	})
+	assert.NoError(t, err)
+
+	// Start the orchestrator.
+	go func() {
+		assert.NoError(t, orchestrator.Run(ctx))
+	}()
+	go taskReaper.Run(ctx)
+
+	observedTask1 := testutils.WatchTaskCreate(t, watch)
+	assert.Equal(t, api.TaskStateNew, observedTask1.Status.State)
+	assert.Equal(t, observedTask1.ServiceAnnotations.Name, "name1")
+
+	// Set the task state to PENDING to simulate allocation.
+	updatedTask1 := observedTask1.Copy()
+	updatedTask1.Status.State = api.TaskStatePending
+	updatedTask1.ServiceAnnotations = api.Annotations{Name: "original"}
+	err = s.Update(func(tx store.Tx) error {
+		assert.NoError(t, store.UpdateTask(tx, updatedTask1))
+		return nil
+	})
+	require.NoError(t, err)
+
+	testutils.Expect(t, watch, state.EventCommit{})
+	testutils.Expect(t, watch, api.EventUpdateTask{})
+	testutils.Expect(t, watch, state.EventCommit{})
+
+	service1.Spec.Task.ForceUpdate++
+	// This should shutdown the previous task and create a new one.
+	err = s.Update(func(tx store.Tx) error {
+		assert.NoError(t, store.UpdateService(tx, service1))
+		return nil
+	})
+	testutils.Expect(t, watch, api.EventUpdateService{})
+	testutils.Expect(t, watch, state.EventCommit{})
+
+	// New task should be created and old task marked for SHUTDOWN.
+	observedTask1 = testutils.WatchTaskCreate(t, watch)
+	assert.Equal(t, api.TaskStateNew, observedTask1.Status.State)
+	assert.Equal(t, observedTask1.ServiceAnnotations.Name, "name1")
+
+	observedTask3 := testutils.WatchTaskUpdate(t, watch)
+	assert.Equal(t, api.TaskStateShutdown, observedTask3.DesiredState)
+	assert.Equal(t, "original", observedTask3.ServiceAnnotations.Name)
+
+	testutils.Expect(t, watch, state.EventCommit{})
+
+	// Task reaper should delete the task previously marked for SHUTDOWN.
+	deletedTask1 := testutils.WatchTaskDelete(t, watch)
+	assert.Equal(t, api.TaskStatePending, deletedTask1.Status.State)
+	assert.Equal(t, "original", deletedTask1.ServiceAnnotations.Name)
+
+	testutils.Expect(t, watch, state.EventCommit{})
+
+	var foundTasks []*api.Task
+	s.View(func(tx store.ReadTx) {
+		foundTasks, err = store.FindTasks(tx, store.All)
+	})
+	assert.NoError(t, err)
+	assert.Len(t, foundTasks, 1)
+}
diff --git a/manager/orchestrator/taskreaper/task_reaper.go b/manager/orchestrator/taskreaper/task_reaper.go
index 88e353b383..0c4e818475 100644
--- a/manager/orchestrator/taskreaper/task_reaper.go
+++ b/manager/orchestrator/taskreaper/task_reaper.go
@@ -251,7 +251,12 @@ func (tr *TaskReaper) tick() {
 
 			runningTasks := 0
 			for _, t := range historicTasks {
-				if t.DesiredState <= api.TaskStateRunning || t.Status.State <= api.TaskStateRunning {
+				// Skip tasks which are desired to be running but the current state
+				// is less than or equal to running.
+				// This check is important to ignore tasks which are running or need to be running,
+				// but to delete tasks which are either past running,
+				// or have not reached running but need to be shutdown (because of a service update, for example).
+				if t.DesiredState == api.TaskStateRunning && t.Status.State <= api.TaskStateRunning {
 					// Don't delete running tasks
 					runningTasks++
 					continue
diff --git a/manager/scheduler/scheduler.go b/manager/scheduler/scheduler.go
index 6d5b4e551b..9ee0b9e5c9 100644
--- a/manager/scheduler/scheduler.go
+++ b/manager/scheduler/scheduler.go
@@ -74,6 +74,12 @@ func (s *Scheduler) setupTasksList(tx store.ReadTx) error {
 			continue
 		}
 
+		// Also ignore tasks that have not yet been assigned but desired state is beyond TaskStateRunning
+		// This can happen if you update, delete or scale down a service before its tasks were assigned.
+		if t.Status.State == api.TaskStatePending && t.DesiredState > api.TaskStateRunning {
+			continue
+		}
+
 		s.allTasks[t.ID] = t
 		if t.NodeID == "" {
 			s.enqueue(t)
diff --git a/manager/scheduler/scheduler_test.go b/manager/scheduler/scheduler_test.go
index 5705e1dcdb..2126e70397 100644
--- a/manager/scheduler/scheduler_test.go
+++ b/manager/scheduler/scheduler_test.go
@@ -2277,6 +2277,94 @@ func TestPreassignedTasks(t *testing.T) {
 	assert.Equal(t, assignment3.NodeID, "node2")
 }
 
+func TestIgnoreTasks(t *testing.T) {
+	ctx := context.Background()
+	initialNodeSet := []*api.Node{
+		{
+			ID: "node1",
+			Spec: api.NodeSpec{
+				Annotations: api.Annotations{
+					Name: "name1",
+				},
+			},
+			Status: api.NodeStatus{
+				State: api.NodeStatus_READY,
+			},
+		},
+	}
+
+	// Tasks with desired state running, shutdown, remove.
+	initialTaskSet := []*api.Task{
+		{
+			ID:           "task1",
+			DesiredState: api.TaskStateRunning,
+			ServiceAnnotations: api.Annotations{
+				Name: "name1",
+			},
+
+			Status: api.TaskStatus{
+				State: api.TaskStatePending,
+			},
+		},
+		{
+			ID:           "task2",
+			DesiredState: api.TaskStateShutdown,
+			ServiceAnnotations: api.Annotations{
+				Name: "name2",
+			},
+			Status: api.TaskStatus{
+				State: api.TaskStatePending,
+			},
+			NodeID: initialNodeSet[0].ID,
+		},
+		{
+			ID:           "task3",
+			DesiredState: api.TaskStateRemove,
+			ServiceAnnotations: api.Annotations{
+				Name: "name2",
+			},
+			Status: api.TaskStatus{
+				State: api.TaskStatePending,
+			},
+			NodeID: initialNodeSet[0].ID,
+		},
+	}
+
+	s := store.NewMemoryStore(nil)
+	assert.NotNil(t, s)
+	defer s.Close()
+
+	err := s.Update(func(tx store.Tx) error {
+		// Prepopulate nodes
+		for _, n := range initialNodeSet {
+			assert.NoError(t, store.CreateNode(tx, n))
+		}
+
+		// Prepopulate tasks
+		for _, task := range initialTaskSet {
+			assert.NoError(t, store.CreateTask(tx, task))
+		}
+		return nil
+	})
+	assert.NoError(t, err)
+
+	scheduler := New(s)
+
+	watch, cancel := state.Watch(s.WatchQueue(), api.EventUpdateTask{})
+	defer cancel()
+
+	go func() {
+		assert.NoError(t, scheduler.Run(ctx))
+	}()
+
+	// task1 is the only task that gets assigned since other two tasks
+	// are ignored by the scheduler.
+	// Normally task2/task3 should get assigned first since its a preassigned task.
+	assignment3 := watchAssignment(t, watch)
+	assert.Equal(t, assignment3.ID, "task1")
+	assert.Equal(t, assignment3.NodeID, "node1")
+}
+
 func watchAssignmentFailure(t *testing.T, watch chan events.Event) *api.Task {
 	for {
 		select {