NTU has been responsible for the tree’s upkeep since 2018, which has been extensive due to the Bramley being diagnosed with incurable honey fungus.
However, the university’s decision to put the tree’s site up for sale has led to concerns about its future.
Dan Llywelyn-Hall, founder of the Mother Bramley Fund, set up to protect the Bramley’s legacy, said: “The structure of the tree is wonderful and it tells a story in every twist and turn of the bark.
“The fact that it is literally connected, rooted, to Southwell is so unique.
“We just want the new owners to understand they are about to be the custodian of a tree which is of great significance to our country and we are very much willing to work with them.
“But, my biggest worry is that they might not be sympathetic to that.”
However, NTU has said it was committed to ensuring the tree will remain in the care of a “responsible custodian”.
“The university aims to also support them with guidance on how to care for the tree moving forward,” a NTU spokesperson added.