New foundation is the key to disease free colonies .
Keep your hives clean and ventilated
At black beeman I change foundation every year ,I make it my self, hand pressed it takes 2 minutes a piece. And then embed it on a clean sterilised frame . The root AMFB is hygiene, around the apiary ,and bad ventilation. If you think about the our bees have to put up with a lot more pressure.They have varroa ,pesticides which we never had to deal with in the past .when your bees fly out and land on some plants that have been sprayed, if it doesn't kill them then they bring it home .which in turn weakens the hive ,and mr Varroa is weighting at home to top it all off .