Mandan is one of the newest pecan cultivars released by the USDA pecan breeding program. We have had only a couple of years experience with this new cultivar and have yet to fruit Mandan at the Pecan Field. I was able to get a fresh sample of Mandan from a grower in Oklahoma so we could look at kernel quality. The photo above has Mandan kernels (top row) compared to Kanza kernels (bottom row). The Mandan kernels are obviously larger but the kernel color is darker and more "veiny" than the Kanza kernels. You will also note that the dorsal groves of Mandan are narrow (can hold packing material) as compared to Kanza. In the past, I've found it hard to market nuts with ugly kernels even if those nuts have good size. Less that perfect kernel quality is one of the major reasons I can't get excited about grafting Mandan.
Mandan does seem to have good cold hardiness. Last week, temperatures at the Pecan Field dropped to around -15 degrees F. This morning, I collected some branches from our Mandan grafts, cut into the cambial zone and found only healthy green tissue (photo at left).
When they released Mandan, the USDA indicated that this new cultivar has good scab resistance. Unfortunately we have found scab on Mandan trees at Chetopa, KS and New Franklin, MO. Scab is easily spotted as black, sunken lesions on the twigs during the dormant period. You can see 3 scab lesions in the middle of the twig pictured at above, right. The number of scab lesions I have seen on the stems of Mandan are similar to the number I see on Pawnee but less than the number of lesions found on a very scab susceptible cultivar like Colby