Thursday, February 27, 2014

Kanza: Seasonal differences

    The summer of 2012 was hot and dry in SE Kansas. Last year, we experienced an usually cool and wet summer. Today, I grabbed a couple of Kanza nut samples to show you just how much weather conditions can influence nut size and quality (photo above). Remember, when it comes to nut size, water supply during the nut sizing period (month of July through early August) determines the size of the shell. How well that shell is filled with nut kernel is determined by soil water availability later in the summer, during the kernel deposition period (August through early September). 
    Water supply was deficient throughout much of the 2012 growing season. Our Kanza nuts reacted to this water shortage by producing smaller and less well-filled pecans. The 2013 growing season provided ample water supply and our Kanza nuts returned to their normal size and kernel percentage.  
    It is amazing to see how much a pecan cultivar can change from year to year. Over the past several years I've been shipping Kanza nuts to a friend in Virginia. I guess he had gotten used to receiving the smaller Kanza nuts produced during the drought years of 2011 and 2012 because, when he received the 2013 crop, he thought I had sent him a different cultivar.

Tuesday, February 25, 2014

Mandan: Notes on nut quality

Mandan, 2013 Crop
    Mandan was released by the USDA based on the fact that it produces a large pecan that ripens early. However, ever since I first saw nut samples produced by this cultivar, I have not been a fan.  The nuts produced by Mandan are indeed large (photo at right) but notice that the nut appears narrow when viewed suture side up (nut on left)  compared to the width of the nut when viewed 90 degrees from the suture (nut on right). This shell geometry is always associated with pecans that produce kernels with narrow dorsal groves.
    Our  Mandan nuts averaged 7.65 g/nut and 58.64% kernel this year. These numbers look impressive but a quick look at the kernels makes you wonder how nutmeats that look so shriveled produce such high percent kernel. The upper side of the kernels often appear wrinkled and veiny. The narrow dorsal groves often traps shell packing material. The back side of every kernel was hollow and depressed indicating a less than perfect kernel fill. Overall, the kernels produced by Mandan were not up to my standards for exceptional kernel quality. When it comes to quality pecan kernels, Kanza and Pawnee are far superior.      

Friday, February 21, 2014

Pecan bark peeling?

'Hark' pecan bark
   I was collecting wood from our scionwood orchard and noticed the unique bark appearance of the Hark pecan cultivar (photo at right). Young trees (roughly 6" in diameter) of this cultivar have very distinctive exfoliating bark. The peeling bark on this tree does not represent some dreaded disease but is simply the natural way this tree's bark reacts to diameter growth. The long strips of curled-up bark reminds me of the bark of a shagbark hickory.
    Bark appearance is controlled both genetically and by the growth rate of the tree. A fast growth rate serves only to exaggerate any form of bark exfoliation. If you look carefully at the bark of different pecan cultivars, you will soon notice distinct patterns of appearance. Let me show you a few examples.

'Major' pecan bark
    Major trees produce a scaly bark that seems flake off in small square patches (photo at left). This distinctive 'Major' bark pattern makes field identification of this cultivar easy at anytime of the year.

'Hirschi' pecan bark

    The bark of Hirschi also appears to crack in square patches (photo at right) but it does not take on the scaly appearance found with Major trees . This bark pattern is not terribly unique among pecan cultivars so it is difficult to identify Hirschi by bark appearance alone.

'Giles' pecan bark 

   Giles trees have a more furrowed bark appearance (Photo at right). The look is mostly non-descript and gives no clue as to the cultivar.  The bark simply looks like bark should look.
     There are many cultivar characteristics that can be used to identify a pecan cultivar. Bark appearance is cultivar specific but only some pecan cultivars produce bark so distinctive that it sets them apart from other cultivars. 

Wednesday, February 19, 2014

A good week for cutting scions

     The cold weather has finally broken and a wave of warmer temperatures has provided ideal conditions for collecting pecan scionwood. For the past several days, we have been harvesting wood from our scionwood orchard. We cut all the long vigorous shoots than have grown since last year's scionwood harvest (photo at right) then bring the shoots inside to be cut into 6-8 inch scion sticks. Tips for cutting scions can be found here and here.
    Note that we don't cut the entire one-year-old branch off the tree. We leave the base of the shoot along with 2 or 3 buds on the tree to provide growing points to produce the new growth we'll need for next year's scions.
   Annual severe pruning is a great way to produce a lot of high quality scions. The Pawnee tree at left produced numerous 3 to 4 foot long shoots last summer. With the aid of a hydraulic lift, we can harvest hundreds of scions from a single tree.
   The shucks still hanging in the tree means that even the most severe pruning did not prevent this scionwood tree from producing a small nut crop last season. Before we start pruning any tree into a full-fledged scionwood tree, we always allow the tree to bear a few nuts so we can verify that the tree is true to cultivar.
    We use plastic tote boxes to store our scions. We line the bottom of the 9" x 14" x 5" box with several layers of paper towels, then dampen those towels with water. These towels provide a moisture reservoir that will keep the wood at 100% relative humidity. Once the box is filled with scions, we place a second layer of moist paper towels over the wood. We then snap the plastic lid in place and the store the wood a refrigerator at 34 degrees F.
    Don't forget to label the box with the cultivar name before placing any wood in the box. We try to fill the box completely to limit the amount of air space inside the box.
    If you need to collect smaller amounts of scionwood, use gallon-sized, zip-lock freezer bags to store your scions. Make sure to label the bag with the cultivar name and place some moist paper towel inside the bag to provide moisture. Since frost-free refrigerators can suck moisture right out of a freezer bag, I always place my collection of freezer bags (each bag with a different cultivar) inside a plastic tote box before storage. The hard plastic box will ensure your wood won't dry out before the grafting season arrives.


Saturday, February 15, 2014

The original Giles tree

The original Giles tree, February 2014
    Just south of the old Missouri-Pacific railroad line and two miles east of Chetopa, Kansas  the original Giles tree still stands among other trees in a native pecan grove (photo at right). Its not a very impressive tree with its forked trunk and scraggly branches. The tree suffered major limb loss back in the 2007 ice storm but has sprouted numerous new branches.
    The Giles pecan was first described by J.Ford Wilkinson back in 1932. Mr. Wilkinson was a nurseryman from Rockport, IN that traveled widely across the northern pecan belt in search of outstanding nut trees. Back in the late 1920's and early 1930's, Mr. Wilkinson made several trips to SE Kansas to graft trees for area growers. In fact, the oldest grafted pecan grove in Kansas (currently owned by Raymond Conard of rural Chetopa) was propagated by Wilkinson.

Giles nuts still litter the ground
    Wilkinson made his trips to Kansas at the request of Mr. A.E. Giles of Peoria, IL.  Mr. Giles owned a pecan grove near Chetopa, KS that contained an outstanding seedling tree that he had named after himself--"Giles". Here is how Wilkinson described the Giles tree in 1932; "In three trips in as many years that I visited this tree it was bearing bountifully, while two of these were not favorable seasons and most of the tree surrounding produced only light crops. A top-worked tree of this variety in my nursery, now four years old, has produced for two seasons, a splendid crop last fall. The nut is good size, thin shell, with kernel of good quality."
     It is interesting to note that the original Giles tree is growing in a ditch that often holds water (photo at right). The reason I still found nuts under this tree in February (photo above) is because when the harvesters picked this grove back in December the ditch was too wet to pick.
   Giles is now fading as a cultivar to graft in new orchards. As a young tree, Giles preforms beautifully. Yields are heavy and nut quality good. However, as the tree matures, problems with pecan scab, over-production, and poor kernel quality make Giles a difficult cultivar for growers to manage profitably.  Giles' most lasting legacy may be that the seeds of this cultivar are still widely used for growing rootstock trees. 

Thursday, February 13, 2014

Pecan scab: Impacts on harvested nuts

Giles 2013
    Last summer, we had a 3 week long wet period in mid-summer that promoted the rapid spread of pecan scab. By the end of the growing season, scab had a drastic impact on nut size. This week we have been cracking nuts samples from a fungicide trial and found wildly different nut sizes all produced by the same tree (photo at right). It almost looks like the nuts come from different cultivars instead being 100% Giles nuts.
    This variation in nut size is entirely due to the variation in scab lesion coverage over the surface of the shuck. Nuts that were entirely covered by scab early during the nut expansion period are much smaller than nuts infected later in the year.
     Scab infection does not spread evenly across all nut clusters in a tree. Nuts on lower and interior limbs typically have more scab than nuts found at the top of the tree's canopy. Remember, scab spreads most readily under conditions of high humidity. Following rainfall or a heavy dew, nut clusters exposed to the sun and wind at the top of a tree dry off much quicker than nuts in the shade and on low, wind-sheltered limbs.

Giles kernels 2013
    The effect of scab is far more serious on kernel quality. The photo at left shows the kernels we extracted from the nuts in the photo above. The kernels are thin and poorly developed and unattractive. There are even a few wafers. A well managed Giles nut should produce over 52% kernel. This sample had only 45.8% kernel.  When we ran our scab-infected Giles crop though our cleaning machine, we blew also one half the nuts out into the refuse pile.

Chetopa 2013
   Giles was not the only cultivar we had in our fungicide test. We also looked at Chetopa.  Scab infection was typically less of a problem on Chetopa but the disease was still prevalent.  In the photo at right, you can see variation in nut size among our Chetopa nuts but really small pecans were not as numerous.
   When we shelled the Chetopa nuts, the kernels were better than Giles kernels but they still did not have perfect nut quality. These nuts produced 52.8% kernel. A disease free Chetopa nut should produce 55% kernel. Although Chetopa had less scab on the shuck than Giles, we still found the disease had a negative impact on nut size and kernel quality.   
   Our experience with scab in 2013 proves one thing: If you are growing scab susceptible cultivars, using the right fungicide at the right time is essential.

Tuesday, February 4, 2014

Selections from the breeding block

   This past fall, we collected over 400 nut samples from our pecan breeding block. Now, in the dead of winter, we've begun to crack out those samples. Many of the nuts we've cracked revealed mediocre nut quality or the pecans that are so small that we can mark the trees that produced them to be cut for firewood. However, a quick look through the samples revealed some pretty awesome looking kernels. I grabbed four samples with bright, plump kernels just to give you an idea of the variation we are seeing among some of the better quality nuts (photo above). Below is a table that gives some of the details of these four seedlings.

   You'll note that Pawnee is a parent to all four seedlings (male parent for three of the seedlings and female parent for the open pollinated seedling). Two of the nuts had Major as the female parent, while one had a Greenriver mother. All four of these seedlings ripened before or at the same time as Pawnee (Oct. 8 in 2013).
   There are other seedlings in our collection that have outstanding nut quality. If you attend the annual meetings of the Nut Growers Associations of KS, MO, and IL this year you'll be able to see some of the better nuts from our breeding block on display. But a word of caution.  It will take several more years of evaluation before we are ready to send out scionwood for advanced testing by growers. We still need to evaluate each seedling for disease susceptibility, cold hardiness, nut bearing potential and tendency towards alternate bearing. It is so easy to fall in love with a pecan that produces a beautiful kernels. But, the history of pecan cultivar development is full of examples of cultivars that looked good as young trees only to turn out to be a grower's nightmare.  

Monday, February 3, 2014

The history of Peruque pecan

2013 Peruque crop
    Peruque--such an unusual name for a pecan cultivar. Pronouned per-u-k, the name Peruque is originally of French origin from the word perruque, meaning wig. This cultivar was found as a native pecan tree growing in the Mississippi river flood plain north of St. Peters, MO. Look at a map of the area and you will find Peruque Creek flowing northward toward the Mississippi. On older maps of the area, you will also find the riverside community of Peruque and a Peruque Island in the middle of the Mississippi River. What you won't find on maps is the landmark that this pecan cultivar was named after--the Peruque railway station on the Burlington Railway Line (long before it became the Burlington-Northern RR). But why early french explorers would name their small, fur-trading settlement along the banks of the Mississippi after the ubiquitous hair piece worn by 17th century, ruling-class men back in their home country is a story lost to history. 
    In 1956, Ralph Richterkessing from St Charles Missouri brought Peruque into the national spotlight when he reported his success with grafting scions from the original tree onto his own trees and the trees of several neighbors. As it turns out, the locals had known about this outstanding seedling pecan tree for over 50 years. The tree was originally known as the Hunn pecan named after the original owner of the tree, George Hunn (owner until 1918). However, Ralph Richterkessing was the first person to successfully propagate the tree and it was William Krause, the tree's owner after 1918, that suggested naming the cultivar "Peruque" after the local railway station.

Bird pecked Peruque pecans
    In 1956, the original tree was still standing--30 inches in diameter and 70 feet in height. The tree was one of several native trees in a grove of trees 1/4 mile from the Mississippi River. It is interesting to read Mr. Richterkessing's description of Peruque as a pecan cultivar. He metioned that Peruque "cracked out at approximately 60 percent kernel. The nuts run around 95 to the pound. The kernel has a bright color and a pleasing flavor. The nut matures about one week earlier than Major...and is somewhat more subject to damage by weevil, birds and squirrels." 
    Our experience with Peruque has been similar to Mr. Richterkessing's. The tree is productive and bears at a young age. The nuts are small but have very thin shells with high quality kernels. Unfortunately this cultivar is susceptible to pecan scab and is extremely susceptible to bird peck and bird pilferage. As an early ripening cultivar, Peruque seems to attract pecan weevils.  Peruque's small nut size will discourage me from grafting any more of this cultivar, but the high percent kernel will prevent me from cutting down mature high-yielding trees.