Dunn has been performing with a sore throat and his doctor has put him on vocal rest for three weeks.
The show that was scheduled for Friday, June 25 at the Comcast Theater will now be on Aug. 14.
"Following my doctor's order, shutting up, getting well and comin' back asap!" Dunn said by text message.
The duo announced last year that they would be going their separate ways and that this would be their last tour.