The singer/songwriter has postponed fives dates on the trek and cancelled two more to undergo a minor medical procedure.
She has axed gigs in Birmingham, Alabama and Augusta, Georgia, and is also re-scheduling five planned concerts in other U.S. states.
All the shows were due to take place in May (14).
A statement on her official website reads, "Due to an unforeseen and urgent health concern that requires immediate attention, we have been forced to reschedule and unfortunately cancel a few select shows on the upcoming tour with Willie Nelson. A list of the affected shows, along with makeup dates and ticket refund/exchange policies, are listed below. We sincerely apologize for any inconvenience."
No further details about Krauss' health issue were available as Wenn went to press.