Can you still generate more Mushroom Armor while in decline? What about the turn you go into decline? There is a little disagreement about how to interpret the rules.
For each Mushroom Forest Region you occupy at the end of your Conquest phase, take 1 Mushroom Armor from the tray in your hand. Deploy these Mushroom Armors in any of your Region(s), during your Troop Redeployment phase. Each Armor placed in a Region augments that Region's defense by 1, even when In Decline. These markers do not count as Race tokens (for instance a single Race token with 1 or more Shields in a Region could still be Vampirized). You can stack multiple Mushroom Armor in the same Region. Remove the Armor and discard them back in the tray when you abandon the Region or an enemy conquers it. Otherwise keep it in play as long as your Shield troops are on the board.
Edited for full rules.