rotting tree limb rot

Hi all, I'd love some help with identifying what to do. I have three trees that seem to have developed some kind of rot (photos attached). Can any of these be saved, or will they all need to be cut down? They aren't particularly tall, so the physical act of cutting them is easy enough, but I'd...

Hello. I have two very old limb cuts that are rotting out and are currently about basketball size deep. It's a 3 foot diameter tree. These holes sit with water constantly. I have taken out as much water and debris as possible and covered partially to prevent any of this rain from entering them...