Back in 1984, when Pawnee was released as a new cultivar it was promoted as an early-ripening, scab-resistant pecan. We have since gained decades of experience with this cultivar and have discovered that Pawnee ripens large beautiful pecans early in the Fall. However, Pawnee has turned out to be quite susceptible to pecan scab requiring multiple scab sprays to keep shucks clean. In fact, I photographed a cluster of Pawnee nuts this morning and found not only black pecan scab lesions but I also found a portion of the shucks were covered with the white powdery mildew fungus (photo at right).
Mandan, 15 July 2015
Mandan was released in 2009, with similar fanfare--large nut, early ripening, and scab resistant. This morning I also photographed a cluster of Mandan nuts (photo at left). And guess what I found? That's right, pecan scab and powdery mildew. We have only been able to see our Mandan trees bear nuts for 4-5 years now but I have seen enough of this clone to say that Mandan is definitely not scab resisitant.