This guide can help you to understand how to defeat spawners.
How to Defeat Spawners (Step-by-Step)
- Place artillery (I used heavy/fire but most artillery besides smoke should work. haven't tried rockets yet.) near the back of the spawn zone, if possible in a clearing. If there isn't enough room place structures like bunkers. They delete trees surrounding them.
- Take control of one of the artillery units via ctrl then press M for the artillery map. This makes using the gun and finding enemy units a lot easier.
- Locate the VIP buildings/spawners from your current position. The Spawners don't show up on the map, however, there is 'usually' an AA gun next to it that will appear on the map. From there on it should be easier to pin point where you need to aim.
- Open fire! You might run out of ammo before destroying the spawner. If so just switch to the next artillery and repeat said steps.