diff --git a/django_celery_beat/migrations/0007_periodictask_origin_key.py b/django_celery_beat/migrations/0007_periodictask_origin_key.py
new file mode 100644
index 00000000..c02f2ef1
--- /dev/null
+++ b/django_celery_beat/migrations/0007_periodictask_origin_key.py
@@ -0,0 +1,25 @@
+# -*- coding: utf-8 -*-
+from __future__ import absolute_import, unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('django_celery_beat', '0006_auto_20180210_1226'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='periodictask',
+            name='origin_key',
+            field=models.CharField(
+                blank=True,
+                default=None,
+                max_length=200,
+                null=True,
+                verbose_name='origin key'
+            ),
+        ),
+    ]
diff --git a/django_celery_beat/models.py b/django_celery_beat/models.py
index d5fe2ddf..2e1a9be3 100644
--- a/django_celery_beat/models.py
+++ b/django_celery_beat/models.py
@@ -267,6 +267,9 @@ class PeriodicTask(models.Model):
     routing_key = models.CharField(
         _('routing key'), max_length=200, blank=True, null=True, default=None,
     )
+    origin_key = models.CharField(
+        _('origin key'), max_length=200, blank=True, null=True, default=None,
+    )
     expires = models.DateTimeField(
         _('expires'), blank=True, null=True,
     )
diff --git a/django_celery_beat/schedulers.py b/django_celery_beat/schedulers.py
index 14885018..18ab11d4 100644
--- a/django_celery_beat/schedulers.py
+++ b/django_celery_beat/schedulers.py
@@ -142,12 +142,19 @@ def _unpack_fields(cls, schedule,
                        args=None, kwargs=None, relative=None, options=None,
                        **entry):
         model_schedule, model_field = cls.to_model_schedule(schedule)
+        schedules = {
+            'interval': None,
+            'crontab': None,
+            'solar': None
+        }
+        schedules[model_field] = model_schedule
+
+        entry.update(**schedules)
         entry.update(
-            {model_field: model_schedule},
             args=dumps(args or []),
             kwargs=dumps(kwargs or {}),
-            **cls._unpack_options(**options or {})
         )
+        entry.update(**cls._unpack_options(**options or {}))
         return entry
 
     @classmethod
@@ -189,7 +196,8 @@ def __init__(self, *args, **kwargs):
 
     def setup_schedule(self):
         self.install_default_entries(self.schedule)
-        self.update_from_dict(self.app.conf.beat_schedule)
+        self.update_from_dict(self.app.conf.beat_schedule,
+                              origin_key='beat_schedule')
 
     def all_as_schedule(self):
         debug('DatabaseScheduler: Fetching database schedule')
@@ -248,18 +256,36 @@ def sync(self):
             self._dirty |= _tried
             logger.exception('Database error while sync: %r', exc)
 
-    def update_from_dict(self, mapping):
+    def update_from_dict(self, mapping, origin_key=None):
         s = {}
         for name, entry_fields in items(mapping):
             try:
                 entry = self.Entry.from_entry(name,
                                               app=self.app,
+                                              origin_key=origin_key,
                                               **entry_fields)
                 if entry.model.enabled:
                     s[name] = entry
 
             except Exception as exc:
                 logger.error(ADD_ENTRY_ERROR, name, exc, entry_fields)
+        if origin_key:
+            # delete database-persisted periodic tasks that
+            # are no longer declared in source code
+            existing_task_instances = PeriodicTask.objects.filter(
+                origin_key=origin_key
+            )
+            existing_tasks = set(
+                map(lambda x: x.name, existing_task_instances)
+            )
+            tasks_to_purge = existing_tasks - set(mapping.keys())
+            if tasks_to_purge:
+                PeriodicTask.objects.filter(
+                    origin_key=origin_key,
+                    name__in=list(tasks_to_purge)
+                ).delete()
+                logger.warn("Purged periodic tasks [origin_key=%s]: %s",
+                            origin_key, ', '.join(list(tasks_to_purge)))
         self.schedule.update(s)
 
     def install_default_entries(self, data):
@@ -272,7 +298,7 @@ def install_default_entries(self, data):
                     'options': {'expires': 12 * 3600},
                 },
             )
-        self.update_from_dict(entries)
+        self.update_from_dict(entries, origin_key='default_entries')
 
     @property
     def schedule(self):