Friday, March 29, 2013

Pecan seedling selections

    Looking over the nut samples at this year's KNGA annual meeting I was struck by several interesting seedling pecan selections made by pecan growers across the Midwest. Let me highlight some of the best.

   St. Genevieve was discovered as a large native pecan tree growing within the city limits of St. Genevieve, MO (photo at right). If you every travel to this historic town, you'll discover that St. Genevieve was originally a French Canadian settlement founded in 1735. You'll also discover numerous native pecan trees growing throughout this Mississippi River town of 4,410 people. St. Genevieve is a large-sized native pecan averaging 8.83 g in weight and 46.7% kernel. This cultivar produces beautiful kernels that fall free from the shell.

    Al Newkirk from Miami, OK has been watching tree #459 in his native grove for a long time (photo at left). The tree produces consistently, bearing medium sized native nuts. This year, nuts averaged 6.54g and produced 48.2% kernel. Al especially likes this pecan because of its disease resistance and has grafted several trees over to this clone.
      Bob Kussman submitted a seedling pecan called Blunk that originates from the native pecan bottoms near Brunswick, MO. Blunk is not a very large pecan weighing only 4.48 g but this nut produces a plump, light-colored kernel that falls free from the shell when cracked (photo at right). For a native nut, percent kernel is high at 50.6%.
   Shepherd is a native nut discovered by Gerald Shepherd. This medium sized native pecan weighed 5.48g this year (drought year) but averages 6.39g when receiving normal rainfall. Shepherd nuts produced 51.4% kernel in 2012 but average 53.0% with adequate moisture. The Shepherd pecan matures 3 days before Pawnee and is scab free (photo at left).
   Ralph Voss  submitted another sample of the Zapp pecan (photo at right). Zapp looks to be a seedling of Stuart, originally planted as a yard tree in Germantown, IL. Nuts are large and blocky weighing 9.58 g in 2012. Nut produced 54.5% kernel last year. Nuts mature two weeks after Pawnee or about the same time as Lakota. Scab has not been seen on this cultivar.

Wednesday, March 27, 2013

Lakota and Mandan

     Every time a new cultivar is released it generates a lot of interest among pecan growers. Lakota and Mandan are the current hot topics among northern pecan growers. We've had Lakota under test a long time but our exprience with Mandan has been limited to just the past 2 cropping seasons.
    Let me start with Lakota (photo above). Lakota was developed by the USDA and field tested at the Pecan Experiment Field. This cultivar originated from a hand pollinated cross of Major and Mahan and was originally tested as USDA 64-6-502. Productivity, precocity, and scab resistance were three cultivar characteristics that made this clone stand out among several other clones we have under evaluation (recent yield and nut quality data in this post).
    Lakota has a protogynous flowering habit and matures its nut about two weeks after Pawnee. Nuts have had an average weight of 7.26 g and 56.85% kernel in our field trials. Lakota produces excellent quality kernels. The kernels are smooth, even colored, and fall free from the shell when cracked. Unlike many older cultivars, the kernel quality of Lakota remains high even under heavy crop loads.
     Lakota will over-produce as trees mature, which can lead to severe alternate bearing. However, alternate bearing can be minimized by using mid-summer shaking to reduce crop load during years of excessive nut set.  In terms of over-production and alternate bearing, Lakota seems to be a scab-free version of Pawnee. I am grafting more Lakota in my orchard.
    Mandan was also developed by the USDA from a cross of  'BW-1' and Osage and released in 2009 (photo at left).  We received scions of Mandan in 2009 and grafted this clone into fairly large trees to encourage early fruiting. We produced nuts in 2011 and 2012.
   Because our grafts are so young, I can not comment of the bearing potential of this cultivar. However, here's what I noticed so far. Mandan has a protandrous flowering habit and has ripened its nuts the same time as Pawnee. We have seen scab develop on Mandan but have yet to have a normally humid spring to determine the severity of scab infection (both 2011 and 2012 were extremely dry seasons).
   Mandan nuts are large, averaging 8.34 g in weight. Our Mandan pecans have produced 60.62% kernel indicating that this cultivar has an extremely thin shell. At this point in our evaluation of Mandan, I'm most concerned about kernel quality. Mandan kernels seem to darken quickly, in the same way Posey and Witte darken to an unattractive kernel color just a few weeks after harvest. Kernels of Mandan are also krinkled and have a tendency to exhibit dark viens, two kernel characterists that make for ugly pecan meats. At this point, I'm not convinced Mandan is a good cultivar choice for the long run. 

Monday, March 25, 2013

Gardner, Faith, and Pawnee

   The cultivar trial we established near New Madrid, MO yielded nuts to allow a direct comparison between three very similar-looking pecan cultivars; Gardner, Faith, and Pawnee. Besides similarities in nut shape, all three cultivars ripen early and are susceptible to pecan scab.
    Pawnee was developed by the USDA and resulted from a cross of Mohawk and Starking Hardy Giant. Gardner originated as a roadside seedling tree discovered in the small village of Gardner, KS. Faith is an open-pollinated Mohawk seedling originally planted by Verna Davis in Arkansas City, KS.
    The evaluation of nuts samples collected in 2012 from the New Madrid point to some differences between these very similar cultivars.

Cultivar      Nut Wt.  % kernel
Pawnee        8.14g       55.81
Gardner        6.87g       57.74
Faith             7.64g       55.01  

   Of these three cultivars, Pawnee and Faith are most alike. However, Faith has constantly produced a smaller nut than Pawnee and Faith nuts may ripen a day or two later than Pawnee. Gardner produces the smallest nut of the three cultivars but Gardner produces significantly more percent kernel. Gardner kernels also seem brighter than Pawnee or Faith, making for a more attractive nut meat.
   We will be looking deeper into differences between these three cultivars in the future. Hopefully, we'll find key cultivar characteristics that can be used to more easily distinguish between these three very-similar-looking pecans. 

Friday, March 22, 2013

Pawnee kernels defects following 2012 drought

    Last fall, many of our Pawnee kernels developed dark blotchy spots in response to last summer's heat and drought. In looking over Pawnee samples provided by growers for this year's nut evaluation, I found a wide range in kernel appearance. The photo above illustrates these kernel defects. There are two kernel halves from each of four Pawnee samples.
    The two kernels in the lower left portion of the photo came from a well irrigated tree that I would consider "normal" in appearance. The kernels in the upper left position suffered the greatest drought induced color changes. These kernels are dark, covered in black blotches and have adhering kernel fuzz. These tree were not irrigated last summer.
    The kernels in the lower right position are less-intensely blotchy and slightly darkened. These kernels were produced by trees had a limited supply of water last summer provided by trickle irrigation. This nut sample points out one of the deficiencies of trickle irrigation in pecan orchards. Under severe drought conditions, many trickle systems can't provide enough water to totally eliminate water stress.
    The kernels in the upper right position illustrate a different type of kernel discoloration.  Rather than numerous small black blotches, these kernels have a large, uniformly-dark area centered on the eye of the kernel (the kernel eye is that area where one kernel half is attached to the other).  With this type of discoloration, the dark spot on underside of the kernel often larger that what appears on the upper side.
    Any type of kernel discoloration will reduce the marketability of pecan crop. A return to more normal rainfall patterns will greatly improve the kernel quality of Pawnee in future years.

Tuesday, March 19, 2013

Timing spring fertilization of pecan groves

    Today we fertilized our pecan grove (photo at right). Renting a fertilizer spreader from the local Coop, we applied 150 lbs urea/acre along with 100 lbs potash/acre.  That figures out to 69 lbs/ acre of nitrogen and 60 lbs/ acre of potassium.  The cost of this application (including spread rent) was $61.35/acre. This application follows the spreading of 100 lbs urea/acre we made last October. 
    Timing fertilizer application is important to ensure that money spent on fertilizer actually gets into the tree. I use two key pieces of information to time the spring fertilizer application: bud development and the weather forecast.
    Starting in March, I scout the grove to see when pecan buds start swelling. The initiation of bud enlargement is marked by a condition called outer scale split.  As buds start to swell in size, the protective scale that covers the bud cracks open and the bud cap falls from the tree. In the photo at left, you can see both outer scale split and a bud whose outer scale has already fallen from the tree.
    Outer scale split also marks the time when pecan tree roots enter their springtime flush of new growth.  Fertilizer is most readily absorbed by actively growing roots, so waiting until outer scale split ensures that the nutrients applied today will be taken up immediately.  
    The second factor in decided to fertilizer today was the weather. The Neosho River is still at very low levels and the chances of a springtime flood seems remote (at least for the next several weeks). Later this week, we are expecting a wintery mix of light rain, sleet, and light snow. This kind of light precipitation will be prefect for moving fertilizer nutrients down into the rooting zone of our pecan trees.     

Monday, March 18, 2013

What about USDA 63-16-182?

  During the Annual Meeting of the KNGA there was a lot of discussion about a USDA clone known as 63-16-182 (photo at left). It seems that down in Georgia, a grower had found a tree of this clone and assumed he had discovered a superior chance seedling. The grower then applied for, and received a patent for this clone calling it "Eclipse". Genetic tests of trees grafted to 63-16-182 and to Eclipse revealed that the trees are genetically identical. Regardless of the name, we have had this clone under test at the pecan Experiment Field since the mid 90's.
    USDA 63-16-182 resulted from a cross of Mohawk and Starking Hardy Giant and is a full sibling of Pawnee. We grafted 63-16-182 into a block of trees that also included USDA 64-6-502, now known as Lakota. Lakota resulted from a cross of Mahan and Major. With these two scab-resistant cultivars established at the same time in the same location, its only logical to compare them. Lets first look at nut quality.

                    63-16-182                  Lakota
              -----------------------     -----------------------
              Nut wt.  % kernel     Nut wt.  % kernel
2010        6.51        60.02         8.81        58.22
2011        5.74        59.68         7.36        56.92
2012        6.31        58.35         7.68        58.67

    USDA 63-16-182 is a long, narrow nut that weights less, on average, than the wider, more-blocky Lakota cultivar (photo at right). The shape (long instead of blocky) and the extremely high % kernel of USDA 63-16-182 makes this clone very susceptible to shell breakage during mechanical harvest.  Kernel color of USDA 63-16-182 is not consistently straw-colored. Darker kernels often appear in cracked samples or kernels may display dark blotches (photo above).

     In terms of yield, a comparison with Lakota is also useful. During the early years of production (2001-2006), USDA 63-16-182 produced, on average, 245 lbs/acre. Lakota trees of the same age in the same block averaged 400 lbs/acre. In 2007, we loss the crop to the Easter Freeze. Later in the December 2007, we suffered an ice storm that severely damaged our orchard. USDA 63-16-182 was among the hardest hit cultivars by ice with over 75% limb loss (photo at right). In contrast, Lakota trees lost between 31% and 50% of their canopy limbs. Since the ice storm, the yield  of these trees reflect the differences between USDA 63-16-182 and Lakota in terms of the severity of canopy loss, rate of yield recovery since the ice storm, and overall productivity.

                Yield (lbs/acre)
           63-16-182    Lakota
2008          0               246
2009          0               710
2010         87             1081
2011        271            1428
2012        881            1694

USDA 63-16-182 ripens about 6 days before Pawnee at our location. That's about the same time as Peruque and 3 weeks earlier than Lakota. The early ripening characteristic of USDA 63-16-182 makes this clone adaptable to many northern pecan growing areas but that advantage is overshadowed by numerous deficiencies we've observed in kernel quality, tree productivity, harvest-ability, and tolerance to extreme weather conditions.  Simply stated, USDA 63-16-182 is a clone I would not include in my orchard.

Sunday, March 17, 2013

Pecan Nut Evaluations

    Last Saturday, the Kansas Nut Growers Association met for their Annual Meeting. The highlight of the meeting was huge display of pecan cultivars (photo above). Each nut sample was cracked and the percent kernel determined. Growers inspected the samples carefully looking at nuts size and percent kernel. The impact of the 2012 drought was easily seen as many cultivars produced smaller than average nuts. However, there were some surprises as some cultivars were still able to produce quality nuts in spite of the dry weather.
   In future posts, I'll be sharing some interesting observations I made when looking over this year's nut samples.

Tuesday, March 12, 2013

Trimming last year's bark graft

    Last summer I top-worked a pecan tree using a bark graft and I showed you every step I took from placing the graft to mid-summer tree training. You can review those steps by clicking on the following posts.

1. Top working with a bark graft
2. Bark graft bursting
3. Training a new bark graft
4. Summer training a bark graft
5. Painting a bark graft

   Since only fresh air could cure my cabin fever,  I decided to go out this afternoon and show you how I  make some important trimming cuts on one-year-old bark grafts.
    My first step is to use a knife to peel into the bark of the stock on the opposite side of the trunk from the scion (photo at left). This gives me some idea how far the stock has died back. The green and cream-colored area is live bark. The cinnamon-colored area is dead tissue. This bark graft is somewhat unusual in that the bark didn't die back farther down the stem. In any case, I now know where I can make an angled cut on the stock to speed the healing over process.
    I like to cut the stock off on least a 30 degree angle (photo at right). This cut will help the tree callus over the wound much faster and will help build a stronger graft union. If  the bark had died back farther down the stock, I would trimmed the tree at a steeper angle to remove all the dead tissue on the top of the stock. With the size of the root system under this tree, I wouldn't be surprised to see this graft healed over by the end of the summer.
    The graft is not the only part of this tree that needs trimming. As you can see in the photo at left, I always like to leave some nurse limbs on a top-worked the tree to help feed the root system with leaf-manufactured carbohydrates. However, you can also see that several of these side limbs have produced shoots that are growing straight up toward the sun (photo at left). These shoots need to be pruned off to help focus all the tree's energy on pushing the new graft.
    I removed about one third of the shoots on the side branches (photo at right). In making my pruning cuts, I concentrated on removing upward growing shoots leaving shoots that where growing laterally. With less direct competition, this graft is now ready to grow vigorously when spring arrives.

Friday, March 1, 2013

Canton: An early-ripening, native pecan

  We've been going over some of our yield data and the results for Canton caught my attention (photos below). Canton is an early-ripening cultivar that was discovered as a native seedling growing near Canton Missouri in the Mississippi River floodplain (NE Missouri). What caught my attention was the consistent and increasing productivity of this cultivar ever since the Dec 2007 ice storm.

Canton shuck split, 7 Sept 2012
   Take a look at our recorded yields (lbs/acre) for our Canton trees spaced 42 ft. by 42 ft. apart (or 24 trees/acre). The trees were grafted in 1986.

        Year          Yield (lbs/acre)
        -------        ------------------
        2008                 1184
        2009                 1112
        2010                 1556
        2011                 2108
        2012                 2476

    The nuts produced produced by Canton trees amount to good quality native pecans (80 nuts/lb and 48.7% kernel)(photo at left). Here's the numbers from the last 5 years.
      Year      nuts/lb  % kernel
       -----      --------  -----------
       2008      69.4        48.9
       2009      86.2        48.9
       2010      86.2        45.4
       2011      76.0        49.9
       2012      86.7        50.5

    Canton produces a strong tree, resistant to wind and ice breakage. This cultivar is moderately susceptible to pecan scab and should be treated with a fungicide for best yield results. If you are growing pecans in a region were length of growing season is a major limiting factor, I would recommend grafting Canton to provide you with consistent nut production.  In areas with a little longer growing season, we have better cultivar choices such as Pawnee, Kanza, or Lakota.