Nut shape defines kernel characteristics

   The other day I was cutting pecans in half to check on kernel quality when I made a simple observation. Nut shape has a huge impact of a couple of important pecan kernel characteristics.
    As I walked down one of our tree rows, I came across three early-ripening cultivars; Faith, Gardner, and USDA 75-8-5. In cross-section,  Faith and Gardner have a similar nut shape--nuts are wide and seem flattened on the suture side (photo above). In contrast, nuts of USDA 75-8-5 appear narrow when viewing the nut from the suture side but are wide in the opposite direction.
    When kernels are extracted from these nuts Faith and Gardner kernels will appear much larger than the 75-8-5 kernels simply because they will be much wider. Now, look at the shell packing material that fills the space in the dorsal grooves of each kernel half. Note that the packing material forms a wide "V" shape in the Faith and Gardner nuts. In comparison, the USDA 75-8-5 nut has narrow fingers of packing material inside deep dorsal grooves.  Narrow dorsal groves often trap bits of packing material in kernel halves making the shelling process more difficult. The "V" shape of the dorsal grooves inside Faith and Gardner nuts will mean that all fragments of packing material will fall free from the kernels during nut cracking.
     

Pecan cultivars spliting shuck in late September

Waccamaw, 28 Sept. 2015

    Over the weekend six more pecan cultivars started to open their shucks. Pictured at right is a seedling cultivar of unknown parentage that originated outside of Golden City, MO. The tree's owner named the tree Waccamaw, after a native American tribe that once inhabited coastal South Carolina. The Waccamaw River flows from North Carolina into South Carolina running parallel to the eastern seacoast. The Waccamaw produces a nut slighty smaller than Pawnee and yields 54% kernel. Waccamaw is scab susceptible.

City Park, 28 Sept. 2015

 

   





     Another seedling pecan we have under trial is "City Park". Years ago, we planted a Giles seedling in Chetopa's Riverside Park. Eventually, the tree started to bear nuts. I was so impressed by the size of nuts produced by this tree that I grafted scions from the original tree into field trials at the research station. The grafted trees of 'City Park' have now matured enough to allow us to get a good read on it ripening date--about the same time as Kanza.

Kanza, 28 Sept. 2015

    Speaking of Kanza, our heavy crop of Kanza nuts have begun to split shuck. Spotting shuck split on Kanza is a little difficult. The shuck separates down the sutures but remain fairly tight around the nut. It will take a killing freeze to really open up the shucks and release the nut inside.

Hark, 28 Sept. 2015

     Like Kanza, I have a strong suspicion that 'Hark' has Major as one of its parents. As a result, the shucks of Hark split down the sutures but the shuck remains tight around the nut until frost.

Posey, 28 Sept. 2015

   















      Posey has a very distinctive shuck that is characterized by a rough surface texture and prominent wings along the sutures. At this time Posey nuts are about 10% shuck split.

Yates 68, 28 Sept. 2015

   Yates 68 looks to be a Posey seedling and shares Posey's dark shell color and tendency for kernels to turn dark quickly after harvest.  Yates 68 was selected from a group of seedling trees planted by Ed Yates on his farm in Southern Indiana. 

Scab on 'Mandan' pecan

    The cultivar release notes published when Mandan was first made available to the public claimed that nuts produced by this tree are resistant to pecan scab. Although not extremely susceptible to scab we have found Mandan shucks infected with the disease.
    This past season we applied a fungicide three times to our Mandan trees during the months of June and July. For the most part, we have kept the shucks mostly clean with only a few small scab lesions appearing by late summer (photo at right).

   However, where we didn't get good fungicide coverage on the nuts, I found several clusters of Mandan nuts covered with scab lesions (photo at left). Mandan also seems to be susceptible to powdery mildew.
    While taking this photo of scabby nuts, I found a crab spider resting on one of the nuts. Crab spiders are a common insect predator in pecan tree canopies with female spiders often hiding their eggs at the base of nut clusters.

More pecan cultivars ripen in late September

Colby, 25 Sept. 2015

    This morning I took a ride in our hydraulic lift so I could get up into pecan tree canopies to check on nut ripening. I found that 10 more cultivars had split shuck including; Colby, Gardner, Goosepond, Major, Mandan, Pawnee, Peruque, Witte and two USDA selections 63-16-182 and 64-11-17 (photos at right and below).
    Among the cultivars I photographed today only Major is resistant to pecan scab. While most cultivars in our trials received 3 fungicide applications, our Goosepond trees are located within a native grove and receive only a single spray. As a result, all the Goosepond nuts were covered with scab. What I found interesting was that many Goosepond nuts still split shuck and will release a smaller-than-normal but sale-able nut.
   Colby and Peruque nuts exhibited high levels of scab despite receiving 3 doses of fungicides. The difficulty we have controlling scab on Peruque and Colby is just one reason among others that these northern cultivars are no longer being grafted into new orchards.

Gardner, 25 Sept. 2015

Goosepond, 25 Sept. 2015

Major, 25 Sept. 2015

Mandan, 25 Sept. 2015

Pawnee, 25 Sept. 2015

Peruque, 25 Sept. 2015

Witte, 25 Sept. 2015

USDA 63-16-182 ('Eclipse'), 25 Sept. 2015

USDA 64-11-17, 25 Sept. 2015