Yes, OSB or Oriented Strand Board, can get dry rot. This is because it has a fault in that if it gets wet, it majorly expands. It can expand up to 15 percent, and never go back to normal. It does succumb to dry rot, and can get so bad that it literally crumbles when you touch it. Dry rot is a type of decay caused by a fungus, and in the case of OSB, when it gets wet it attracts the fungus and gives it a place to grow. If enough gets into it, it can totally ruin the OSB, and make it fall apart and shred like newspaper. The only way to stop this is to prevent the OSB from getting wet.