it wasn't boo radley who filled the whole, it was his older brother nathan radley. he does it to stop the gifts to the children from happening. he says its because the tree is sick (that the knothole makes it sick) but that is not the case
Mr. Radley filled the knothole up with cement.
They can not because the knothole is filled with cement by Mr. Radley
Jem and Scout discovered that someone had filled the knot hole with cement, sealing off the opening where gifts had previously been left for them by Boo Radley. This action by Nathan Radley signified the end of their secret communication with Boo.
Nathan Radley fills the tree hole with cement because Jem and Scout had been leaving items inside of it for Boo. Boo was taking the items and replacing them with his own home made items. Nathan Radley wanted to end the communication between Boo and the Finch siblings.
Mr. Radley cut off Boo's only link to the outside world by sealing the knothole in the tree with cement. Boo Finch used to communicate with Jem and Scout by leaving small gifts and trinkets in the knothole.
Nathan Radley knows Boo has been leaving gifts there for the children so fills the hole in with cement. When the children enquire as to why he's doing this, he lies and says that the tree was dying and this would save it.
It happens in chapter 7. That's when Mr. Nathan Radley puts cement in the knothole.Mustache! :{)AHA
Yes, Mr. Radley indeed blocked the hole. He wanted the children and Boo radley to stop the communication.
The person who closes up the knothole in "To Kill a Mockingbird" is Nathan Radley, Boo Radley's older brother. He fills it with cement to prevent communication between the kids and Boo, as he believes it is leading to trouble.
In "To Kill a Mockingbird," Jem discovers that someone has left gifts for him and Scout in the knothole of the tree by Boo Radley's house. When Nathan Radley fills the knothole with cement, Jem is heartbroken because he realizes that Boo Radley was the one leaving them gifts, indicating that he has been watching over them and cares for them.
Mr. Radley was responsible for the knothole incident because he filled it with cement to prevent communication between Boo and the Finch children. This actions caused Boo to feel isolated and cut off from the outside world.
In my opinion, Mr. Radley lied when he claimed he filled it because the tree was sick. I do not know much about trees, but how can cement help a sick tree? I think Nathan Radley filled the knothole simply to keep Boo from communicating with the children. Possibly feeling a need to protect Boo from getting into trouble.