what can I use to 'plug' this hole?
Some years ago a limb on an apple tree was cut off from wind damage & a hole remains the now healed over area where the limb was. I'm afraid water or ? will get into thoe hole & start some rotting of the tree. Is there some kind of 'clay', cement or similar I can plug this hole with? I realize the broken limb left a very unhealthy area where it once was!