--- a/taskcluster/taskgraph/task/legacy.py
+++ b/taskcluster/taskgraph/task/legacy.py
@@ -163,16 +163,40 @@ def remove_caches_from_task(task):
                 try:
                     scopes.remove(scope)
                 except ValueError:
                     raise ValueError("scope '{}' not in {}".format(scope, scopes))
     except KeyError:
         pass
 
 
+def remove_coalescing_from_task(task):
+    r"""Remove coalescing route and supersederUrl from job task
+
+    :param task: task definition.
+    """
+    patterns = [
+        re.compile("^coalesce.v1.builds.*pgo$"),
+    ]
+
+    try:
+        payload = task["task"]["payload"]
+        routes = task["task"]["routes"]
+        removable_routes = [route for route in list(routes)
+                            if any([p.match(route) for p in patterns])]
+        if removable_routes:
+            # we remove supersederUrl only when we have also routes to remove
+            payload.pop("supersederUrl")
+
+        for route in removable_routes:
+            routes.remove(route)
+    except KeyError:
+        pass
+
+
 def query_vcs_info(repository, revision):
     """Query the pushdate and pushid of a repository/revision.
 
     This is intended to be used on hg.mozilla.org/mozilla-central and
     similar. It may or may not work for other hg repositories.
     """
     if not repository or not revision:
         logger.warning('cannot query vcs info because vcs info not provided')
@@ -468,19 +492,20 @@ class LegacyTask(base.Task):
                 tier = task_extra['treeherder'].get('tier', 1)
                 if tier != 1:
                     # Only tier 1 jobs use the build time as rank. Everything
                     # else gets rank 0 until it is promoted to tier 1.
                     task_extra['index']['rank'] = 0
 
             set_interactive_task(build_task, interactive)
 
-            # try builds don't use cache
+            # try builds don't use cache nor coalescing
             if project == "try":
                 remove_caches_from_task(build_task)
+                remove_coalescing_from_task(build_task)
                 set_expiration(build_task, TRY_EXPIRATION)
 
             decorate_task_treeherder_routes(build_task['task'],
                                             build_parameters['project'],
                                             build_parameters['head_rev'],
                                             build_parameters['pushlog_id'])
             decorate_task_json_routes(build_task['task'],
                                       json_routes,