A good week for pecan harvest

     Its not often that we see the golden yellow of pecan fall color but this year all the trees in my grove put on a beautiful display (photo at right). All week the weather was clear, dry, and warm--perfect weather to start harvesting pecans.

 

   On my farm, pecan harvest is a one man operation that involves my use of several types of pecan harvesting equipment. The first step in the process is to use a three-point-hitch mounted trunk shaker to dislodge to nuts from the tree (photo at left). To me, tree shaking is the most exciting part of pecan harvest. The sound of nuts raining down on the metal canopy of my tractor gives me an immediate idea of  how well each tree has produced this year.

    Once the nuts are on the ground, I jump into different tractor that has a pecan harvester attached (photo at right). Sweeping nuts up off the ground with the harvester is a slow but steady process. I always start harvesting just outside the drip line of the tree then work my way inwards towards the trunk. My Savage harvester picks up nuts in a 5 foot swath so, on larger trees, it takes multiple passes to cover the ground. I've learned to be especially careful when maneuvering the picker near tree trunks. The front outside corner of the harvester can leave an ugly scar if you get too close. 

     Once the pecan harvester's hopper is full, I drive towards my barn to dump the hopper into a pre-cleaner. The pecan harvester picks up more than just pecans. When I dumped the hopper this year, I saw a mixture of nuts, stick-tights, shucks, sticks, and even acorns. Thankfully, I didn't pick up any mud balls this fall--soil conditions were ideal for harvest this fall. The pre-cleaner does a good job of removing sticks, shucks and leaves from the nuts. Next, I run the crop through a cleaner inside my pecan barn. The cleaner is good at removing poorly filled pecans and any nuts that were thinned off during mid-summer crop load adjustments. The final step in the cleaning process is to visually inspect every pecan as they move down an inspection belt.  This year, acorns and green hulled nuts are the most common items thrown off the inspection table.

   Back last spring, the 2020 crop year looked to be an outstanding year for Kanza. I had full crop of Kanza nuts and was excited to be able to reap the rewards of years of tree care. But like everything else this year, the unexpected can ruin the best laid plans. The summer of 2020 was extremely dry in our area. Corn fields withered and pecan trees suffered. The photo at left exemplifies what a lack of summer rainfall can do to a Kanza crop. 

     Under drought conditions, Kanza nuts were almost 2/3 their normal size, while some nuts were even smaller. During harvest, I picked up numerous Kanza nuts still held inside green shucks. I cut open several green nuts (photo above) to reveal a total lack of normal kernel development. It is obvious to me--no water, no kernel development.

   

 

Heavy Kanza Nut Set

    Last week while I was scouting nut clusters for pecan nut casebearer activity, I was surprised to find that my Kanza trees had set an unusually heavy crop. It was just not the fact that a high percentage of terminals were bearing nut clusters but each cluster contained an usually large number of nuts (photo at right shows a cluster of nine Kanza nuts).

    From past experience, I've found that Kanza usually produces 3 to 5 nuts per cluster. So why the the difference this year? The number of pistillate flowers produced by a pecan tree is the product of the previous season's crop load, the nutritional health of the tree, and rainfall during the kernel filling period the prior summer.

    Last year we had ample rainfall throughout the growing season and I always try to make sure my trees receive adequate fertilizer both spring and fall.  In addition, last year I used summer shaking to  reduce a heavy crop load.  The result of this combination of weather and crop management turned out to be ideal for promoting flowering this past Spring. 

    There is no way a pecan tree can grow and fill a canopy full of 9-nut clusters. This kind of crop load will lead to limb breakage and poor kernel filling. To reduce the crop load, I plan to shake all my Kanza trees once again this summer.

Kanza holds on all winter

Kanza 7 March 2020

    The 2019 pecan harvest season was a wet one. On my farm, I could never harvest the nuts from two Kanza trees because the ground around them never had a chance to dry out. I use a Savage pecan harvester to harvest my crop and I've learned over the years that you can plug up a harvester with mud trying to pick pecans on wet ground. So, in the end, I had to leave two Kanza trees unharvested due to wet soil conditions around the trees.
    Last weekend,the sun was shinning and the soils in my pecan grove just beginning to dry out enough to allow me to work in the orchard. I walked over to the unharvested Kanza trees to see if I could grab a snack and was surprised to see that much of the crop was still hanging in the tree (photo at right). In my view, holding on to the nut crop is a positive attribute. My orchard as already been swept clean by 2 flash floods during this winter and early spring yet most of the remaining Kanza nuts were still hanging in the tree, safe from flood waters or simply rotting on wet ground.
  With the forecast for more rain next week, I'll probably never get to harvest the nuts from these two Kanza trees. However, it good to know that Kanza will hold on to its crop until I get ready to shake nuts from the tree.

Comparing Kanza and Hark nuts

   This fall I have been taking a closer look at the performance of Hark as it compares to Kanza. Earlier this Fall I collected a nut sample from a Hark tree and an adjacent Kanza tree. I weighed out these samples and cracked the nuts to determine percent kernel.
   As you can see in the photo above, Hark produces a nut that is slightly larger than Kanza. The shell markings on the Hark nut are very similar to its Major parent. Both Major and Hark shells are covered with many small black speckles. In contrast, the Kanza nut shell is light colored and has few black markings. Even though Kanza has Major parentage the shell of Kanza is more reminisent of its other parent, Shoshoni.

    This year my Hark nuts yielded more percent kernel than my Kanza nuts (photo above). Hark kernels also appeared larger. However, Kanza kernels were lighter in color and appeared more attractive than the Hark kernels. For the first time, I noticed that the dorsal grooves on Hark kernels are narrow and can trap packing material. In fact, if you look closely at the left dorsal groove of the left Hark kernel you'll see some trapped packing material.
   Even though Kanza still remains my favorite cultivar, I plan to graft more Hark into my orchard. Hark is scab resistant and a good pollinator for Kanza.

Kernel Filling: Kanza vs. Hark

Kanza, 6 Sept. 2018

    This fall I'm taking the time to closely compare the performance of Hark to Kanza. As readers of this blog know, Kanza is my favorite pecan cultivar because it produces high quality kernels, is scab resistant, and produces good pecan crops annually. Hark is a relatively new cultivar that has shown great promise. In comparison to Kanza, Hark has similar nut size, kernel quality, ripening date, and scab resistance. The importance of Hark is that it is protandrous and would be a prefect pollen partner for Kanza, a protogynous cultivar.   However, being a new cultivar, Hark does not have a long track record of performance. How will a 40-year-old Hark tree perform? It will be decades before we find out.

Hark, 6 Sept. 2018

   Today, I stopped by my Kanza and Hark trees to check on their kernel development. Seeing a good crop of pecans on both cultivars gets me excited for the coming harvest season.

    I pulled a cluster of Kanza nuts off a tree then collected a similar cluster from a Hark tree. Holding both clusters in my hand (Kanza on left, Hark on right), I photographed the nuts  to give you a good idea about the size of these nuts. In the photo above, it looks like Hark is a little larger than Kanza.

   I cut a nut from each cultivar to check on nut development (photo above). The shells inside reveal that the nuts are very close in size. But note the thicker shuck on Hark. This is why Hark looks bigger than Kanza while still green and hanging on the tree. I also noted that Kanza is a little behind Hark terms of kernel filling. However, with all the moisture we've received the past few weeks, both cultivars should have no problem packing the inside of the shell with kernel.  

Pecan kernel filling

    I cut open a Kanza nut today and captured the kernel filling process in progress. The first thing I noticed when slicing the nut in half is that the shell was completely hard. In the photo above, the arrow marked "S" points to the shell. At this point in time, the outer shell of the nut is fully formed and light tan in color.
    The arrow marked "K" points to newly formed pecan kernel. The white creamy color is what we expect pecan kernel to look like. However, inside the white kernel layer is a translucent layer I've marked "J". This is rapidly forming kernel tissue that has yet to fully differentiate into its final solid white state.  The translucent appearance of this not-yet-fully-formed kernel tissue is the origin of the term "gel stage".
    When I first started working with pecans I was given the impression that kernel development progressed from water stage, to gel stage, to firm kernel. It was almost like the water turns to gel then solidifies into kernel. This is not how it works.
   New kernel tissue develops starting from just under the pecan seed coat. As new kernel tissue develops, the water inside the nut is absorbed back into the tree. The amount of "gel" that can be seen inside the nut is dependent on the speed of kernel formation.  The rate of kernel deposition is influenced by weather conditions and cultivar. This is the most "gel" I've ever found inside a Kanza nut. In past years, the gel layer was much thinner.  
   Kernel deposition is not the only pecan tissue I've seen with this translucent appearance. Back during grafting season, I noticed several stock trees with a layer adjacent to the cambium that had a water soaked or gel type look. This was obviously new wood tissue being formed that hadn't fully solidified. 
     Now when I think about pecan kernel development, I think of it in two stages. The first is "ovule expansion". Ovule expansion occurs during the first half of the growing season as pecan fruit grow rapidly in size. The culmination of this stage occurs when the nut achieves its full size and the inside of the nut is filled with water.  The second stage is "kernel deposition". Kernel begins to develop on the inside of the seed coat and works it way towards the center. Kernel deposition continues until the shuck starts separating from the shell (shuck split).

The new pecan cultivar, 'Hark', looks promising

    We've had 9 inches of rain over the past week and I've found it hard to get out in the grove to look at pecan trees and take photos. Fortunately, the sun popped out today and I was able to take a quick look around a portion of my orchard. The nuts on most cultivars are fully sized with Kanza and Hark at full water stage. My oldest Hark tree has a trunk about 7 inches in diameter and has developed a nice full canopy (photo at right). This tree is located right next to a couple of Kanza trees so its easy to compare these two scab resistant cultivars.
    As a young tree, Hark is easier to train than Kanza. Hark seems to have a more naturally spreading growth habit and produces fewer stalked buds than Kanza. As you know, stalked buds grow into narrow-angled branches that are prone to wind breakage. Although Kanza is not a terribly hard tree to train, I do need to keep a close look out for stalked buds during the early years of tree development. 

    The 2018 crop load on Hark appears to be very similar to my adjacent Kanza trees. The nut yield won't be limb breaking but the 2018 crop appears "good" on both these cultivars. In fact, Kanza and Hark have the best nut set of any cultivars growing on my farm this year. Hark set nuts mainly in clusters of three (photo at left). This cluster size is similar to Kanza and to Major, a parent of both Kanza and Hark.
   With plenty of moisture available to fill out kernels, I'll be anxious to compare the nut quality of Kanza and Hark this coming Fall.

Thinning more Kanza trees

      For the past six years, we have been progressively thinning a three acre block of Kanza trees. This week, we removed trees within the Kanza block in areas where adjacent trees were competing for sunlight and according to our thinning plan (photo above).  During this sixth year of thinning, we cut down 15 trees; the most we've removed in a single year. The original tree planting had 144 Kanza trees. After removing 15 trees this year, we'll be down to 96 trees in the orchard.  The first thinning will be complete when half the trees have been removed and we are down to 72 trees in the 3 acre orchard.  

    The figure at right is a map of the Kanza block as it appeared before we cut any trees this winter. Each tree is depicted by a green circle with a diameter proportional to the tree's trunk diameter. As you can see, tree growth has not been even across this orchard. Tree growth has been fastest in the northern 1/3 of the orchard.  As a result, we've thinned more trees in this area of the orchard. However, trees in the southern half of the orchard continue to grow and will require thinning eventually.

    We removed 15 trees from the Kanza Block this year.  Trees cut down are marked by black circles on the map at right. We thinned trees over the entire planting but most removed trees were located in the middle third of the orchard.
   Up to this point, I've been pleased with this progressive approach to orchard thinning. By taking out trees on an as-needed basis, we have been able to maintain good light penetration into the orchard while preserving high yields. 

Kanza yield 2016

   As most readers of this blog will know, I am a big fan of the Kanza pecan (photo at right). At the Pecan Experiment Field we have a 3 acre block of Kanza trees that was established when we planted nuts in the field to produce rootstock trees back in 1996.  These seedling trees were then grafted to Kanza during the years 2000-2003. The original planting contained 144 trees but since 2012 we have been removing trees as adjacent trees start to crowd. My goal was to maintain a high level of nut production while preventing tree over-crowding. I outlined this gradual thinning plan in a blog post back in 2012.
     By 2016, we have removed 33 trees, yet total yield per acre has increased (table below). Yield was negatively affected in 2011 and 2012 by intense summer droughts and small nut size.
     We saw the first indication of Kanza over-producing in 2016, so I expect a drop off in yield in 2017.  In addition, I've marked 15 trees in the Kanza block for removal this winter. Can the remaining trees make up for the lost production from thinned trees?  I guess we'll find out come next fall.
 

In the eye of the beholder: Kanza and Pawnee

     Kanza and Pawnee are the two most popular pecan cultivars being propagated for northern pecan growers (photo at right).  The decision growers make to graft one or both of these cultivars is largely based on the expectation that the nuts they produce will command top dollar in the marketplace. However, the way growers look at pecan cultivars may be entirely different than the way consumers judge pecans.
   Consumers are visually oriented. Given the choice between several, in-shell cultivars most consumers will be attracted to the largest nut and immediately ask if the nut is a "paper shell". It doesn't seem to matter if a quality kernel actually resides inside the shell. Given the choice between Kanza and Pawnee, most in-shell buyers will choose Pawnee based solely on its larger size.

   Everything changes when the nuts are cracked (photo at right). Once a consumer can see the kernel, different visual cues come into play. Kernel color makes the greatest impression. In the minds of the consumer, a light, straw-colored kernel is associated with freshness. Dark or mottled kernels are associated with off-flavors even if the kernel is actually top quality.
    Kernel appearance is where Kanza really shines. A bag of cracked Kanza nuts is filled with plump, light-colored kernels. Cracked with a modern pneumatic pecan cracker, Kanza kernels not only look pretty but entire kernel halves are often freed from the shell.
    In comparison, Pawnee kernels vary widely in appearance, even when harvested from a single tree. Some kernels have a nice golden color while others appear mottled (photo above). This causes the consumer to pause and ask if the mottled kernels have something wrong with them. Offering a taste sample may be the only way to convince a consumer that a mottled Pawnee kernel tastes just fine.
   Its unfortunate that taste, that one human sense that should guide consumers,  is rarely used to select pecans within the marketplace. Both Kanza and Pawnee have excellent flavor, although their flavors differ. Kanza kernels taste sweet and oily while Pawnee kernels have a distinctive buttery flavor. Personally, I like the flavor of both nuts and I find it refreshing to switch up a recipe by simply using a different pecan cultivar.  

What happens when Kanza over-produces

   Kanza has been one of the best cultivars for our region. But no pecan cultivar is perfect. This past growing season (2016) was the first time I've seen Kanza produce too many pecans. The crop was so heavy on some trees that we saw upper limbs snap under the weight of the crop (photo at right). What was interesting to me was how Kanza responded to the excessive nut load.

    After harvesting our Kanza crop, I noticed that the size if the nuts was far more variable than in previous years (photo at left). Nuts differed is size from larger than average to very small. For the purpose of taking a photo, I combed through a super sack of Kanzas to find pecans that would represent the kind of variation I was seeing. The majority of nuts were medium sized however I definitely noticed a sprinkling of small nuts in the sack.
    To give you an idea of the variation in nut size I found I weighed the 8 nuts in the photo. The table below gives you my results. In looking over the numbers, its good to remember that our long term average for Kanza is 5.15 grams per nut. You can definitely see that I tried to pick out the extremes in nut size for the photo.

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Kanza Nut Weights (g)

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8.74        5.69

8.05        4.24

7.44        3.72

5.83        2.10

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     Over production not only effected nut size but influenced kernel fill. In cracking out Kanza nuts this year I found most nuts were plump and perfect as usual. But, I also found kernels the had hollow looking undersides. It became clear to me that this year's Kanza crop was suffering from over production. However, how our trees responded to the overproduction is fairly unique among pecan cultivars. In my experience, trees that bear too many nuts respond in one of two ways; They produce a tree full of small nuts or all the nuts have normal size but the kernels are poorly filled. Kanza seems to do a little of both, while still producing a majority of nuts with high quantity. However, I've learned a valuable lesson in 2016. Like most improved pecan cultivars, Kanza would benefit from mid summer tree shaking to reduce excessive nut production. 

We need a good freeze to advance harvest

    Today, I walked out to my Kanza trees to check on the progress of the crop. Kanza shucks split open a month ago but I found most shucks still look like they did in late September. The split shucks are still green and still completely covering the nut inside (photo at right). A good hard freeze (26 F) would kill these green shucks, cause nuts to open up, and allow the pecan to finally dry.
   However, the forecast for the first week of November does not include any freezing temperatures.
 

   In the absence of a hard freeze, Kanza shucks will slowly start to dry and pull away from the nut (photo at left). This shuck drying process is painfully slow and occurs at varying rates both within a nut cluster and between clusters on the same tree.
    I like to wait until all the shucks are open and the nuts are fully dry before I start shaking Kanza. By waiting, I can shake once and get the entire crop on the ground at one time.

Thinning trees from a Kanza block

    In keeping with our plan to gradually thin our block of Kanza trees, I cut down nine trees yesterday (photo at right).  We started thinning this block of 144 trees back in 2012, removing 5 to 9 trees each year since that time. So far we have removed a total of 34 trees in 5 years time.

    The map at left shows the position of the trees we removed in 2016. Each green circle represents a tree with the diameter of the circle proportional the the diameter of the tree. The black circles represent trees removed this week.
    So far I've been pleased this this progressive approach to orchard thinning. By removing just a few trees each year we have been able to prevent orchard overcrowding while maintaining total orchard yield. You can review the yield and tree removal history of this block of Kanza trees in this post:

Kanza nut yield for 2015

Kanza nut yield for 2015

    Kanza has become one of the most popular cultivars across many northern pecan states. Back in 1995, we established a three-acre block of Kanza trees and I'm sure glad we did. In 2015, the trees in this block produced a great crop of nuts (photo at left). 

    Just before shaking and nut harvest you could see the the 2015 Kanza crop was going to be a good one. The trees produced nuts throughout each tree's canopy (photo at left).

     After cleaning our Kanza crop and weighing the nuts, we learned just how well these trees performed. Twenty years after starting a new orchard from seed and grafting the resulting seedlings to Kanza, we harvested over 1500 lbs. of pecans per acre (Table below).
    In looking over the table let me point out a few things. First off, you can see how drought during 2011 and 2012 impacted both total yield and average nut weight.  With the return of normal rainfall starting in 2013, nut yield steadily increased during the period of 2013-2015. This increase in yield occurred even as we removed trees using our gradual thinning plan. When the first thinning is complete, we will have removed 72 trees within the three acre block.

A Kanza story

    Back in 1969, Dr. G. D. Madden, the USDA's pecan breeder at the time, sent a package of scions from several pecan selections to the Pecan Experiment Field for testing under northern growing conditions. Among those scions was a clone labeled USDA 55-11-11.  Back in those days, the staff at the Pecan Field grafted all new cultivars received for trial onto small native pecan trees that grew within areas of larger native trees. As it turns out, only one USDA 55-11-11 tree was successfully produced from that spring's grafting efforts and has now grown into a large tree (photo at right).
     When I first arrived at the Pecan Experiment Field in 1981, our 55-11-11 tree was already bearing regular crops of nuts. During the early 1980's, KNGA member, pecan enthusiast, and parish priest, Tony Blaufus made an annual trip to the Pecan Field to look over our cultivar collections. Tony had started a small grove of trees on his family's farm near Westphalia, KS and was interested propagating the best available pecan cultivars he could find. It was Tony that first pointed out  to me how well nuts from the 55-11-11 tree shelled out and how wonderful the straw-colored kernels tasted. That's when I decided to remove a couple of nearby native trees to give our lone 55-11-11 some more room to grow. I also started to graft additional USDA 55-11-11 trees into formal cultivar trials.

      In the early 1990's, I started to encourage the USDA to name and release USDA 55-11-11 as a new pecan cultivar for northern pecan producers.  I even suggested a name--Kanza.
    In 1996, Kanza was released and has since become one of the most popular nuts being propagated in northern pecan states. And what has happened to that single tree grafted back in 1969?  It is still standing and has grown to 25.1 inches in diameter (Photo at left).
    I have been fortunate to be able to watch a single Kanza tree grow from a young productive nut producer into a fully mature tree that reliably yields outstanding-quality pecans year after year after year. In the past, we've made cultivar choices based on the performance of young trees only to be disappointed by those same cultivars as trees mature. Too many times, I've seen cultivars that produced outstanding nuts on productive young trees only to mature into old trees with severe alternate bearing, poor quality kernels and susceptibility to winter cold damage. With Kanza, I've been able to watch this cultivar long enough (35 years) to know I won't be faced with future disappointments. 

     Kanza originated from a hand pollinated cross between Major and Shoshoni made by Louis Romberg in 1955. Louis was the USDA's first pecan breeder hired way back in 1931. The objective in making a cross between a northern cultivar (Major) and a large, thin-shelled cultivar of southern origins (Shoshoni) was to develop a new pecan cultivar with large nut size, thin shell and early ripening. The photo at right shows a Kanza nut and its shuck. When I look at Kanza, I can see characteristics from both parents. Kanza inherited the tear-drop shape, thin shell and excellent shelling ability from its Shoshoni parent. From its Major parent, Kanza inherited scab resistance, a thick firm husk, early ripening, and great kernel flavor.
     In the 1960's, many pecan "experts" judged USDA 55-11-11 not worthy of propagation. The nut produced was deemed too small for modern commercial orchards that only had room for cultivars that produced mammoth sized nuts.  At that time in our history, it didn't seem to matter if those big pecan produced kernels that tasted like cardboard. But times change, and consumers are becoming more concerned with kernel quality and flavor rather than just a big shell.  

    Kanza is among the best shelling pecans that can be grown. After cracking, Kanza nuts produce over 95% intact kernel halves (if the cracker is set properly). The kernels are golden in color and very attractive (photo at left). Get a customer to taste a Kanza kernel and you'll have them asking for the nut by name from now on. 

Kanza performance 2014

2014 Kanza crop

   If you have been following this blog for some time, you know that I have been documenting the yield and performance of a three acre block of Kanza trees. This year we harvested a good crop of nuts, averaging 1268 lbs/acre (see table below).  
     In looking over the records for this block of trees, it is interesting to see the impact of below-average rainfall on tree performance. During the years 2011, 2012, and the first half of 2013 the trees suffered from serious water shortages. Drought conditions impacted tree grow rate, nut weight, and yield. In 2013, mid-summer rains helped to increase nut size but yield had already been impacted by the previous season's drought. You see, each spring's pistillate flower production is largely determined by growing conditions during the nut filling period the previous summer. 

   

Cracked Kanza nuts, 2014

    In 2014 tree grow rate responded to better soil moisture conditions and total pecan yield increased. However, the dry spell we experienced in mid- summer decreased nut size and increased the number harvested stick-tights.    
    Over the years, we have progressively thinned this Kanza block as trees begin to crowd. The thinning plan for this orchard and our tree removal progress has been posted to this blog. When planted, this block of trees contained 144 trees spaced 30 feet by 30 feet. So far we have removed 17 trees but the thinning plan calls for the eventual removal of 72 trees in total (resulting in a 42 ft. x 42 ft. spacing). However, by taking a thin as needed approach to tree thinning,  we have maintained total block yield despite experiencing problems with drought.

Kanza, stick-tights and crop load regulation

  Kanza has become a very popular pecan cultivar because no matter the weather, Kanza always seems to produce a quality kernel (photo at right). Over the past four years, I've been watching our Kanza trees closely and I think I've  discovered one of the ways these trees preserve kernel quality even when faced with stressful weather conditions.  It looks like Kanza trees self thin a portion of their nuts to ensure full kernel filling for the rest of the crop.

    We recently harvested a block of Kanza trees and had dumped a load of nuts into the pecan cleaner. When I looked at the nuts swept up by the harvester, I noticed a large number of stick-tights. The photo at left shows an example of field run Kanza nuts before cleaning. There were plenty of good Kanza nuts mixed in with a few sticks, leaves, and dirt clods. But what stands out are the nuts trapped in blackened shucks.
   It turns out that about 12% of Kanza nuts collected by the harvester this year were stick-tights. Just looking at the photo it seems like the percentage should be higher but a nut stuck in the shuck takes up a lot more space than a nut out of the shuck. 

   I separated out several of the stick-tight pecans, peeled the shuck off, and cracked open the nuts. In every case, I found a brown, paper-thin kernel inside. It looks like each of these stick-tight pecans stopped kernel development at the water stage leaving only the seed coat inside the shell.
   The question becomes--"Why did these nuts stop developing during the water stage?".  During the summer of 2014, we experienced an extended period of dry weather that started during the final stages of nut sizing and continued until late August. In addition, our Kanza trees had set an above-average crop. Most pecan cultivars react to these circumstances by aborting a portion of their crop in what is commonly known as a water stage drop. Nuts dropped in mid-summer often disappear by harvest as they decompose in the ground cover.
   Kanza is different. A Kanza tree stressed by drought and crop load turns off the nut development process during water stage for a portion of the crop but those nuts remain on the tree until harvest. 
   The good news is that Kanza seems to do an excellent job of regulating its crop load to ensure that fully ripe nuts are well filled. The bad news is that cleaning the Kanza crop following a mid summer drought will take a little more time to remove numerous stick-tights. 

Shuck split acoss the midwest

   Last week, I visited 6 pecan orchards across 3 states to check on how pecan shuck split varies with location. Below is a map of the orchards I visited all in the space of 3 days.

      By looking at the map you can see that I traveled both east and north from my home base in Chetopa, KS. What the map doesn't show you is how the seasonal climate differs between these pecan orchards. In the Table below I have listed the annual average cooling degree days for each location as well the the average number of frost free days (above 32 F), and the average number of freeze free days above 28 degrees F.
    Cooling degree days are calculated by the National Weather Service (NWS) as a measure of summer heat used to estimate the energy demand needed for refrigeration and cooling. But cooling degree days also can be used to estimate the amount of heat a pecan tree receives during the summer. Pecan is a heat loving crop and even the earliest ripening pecan cultivars require significant summer heat to fill out kernel and ripen (see pecans and climate).
    The freeze free days above 32 degrees is the most common measure of length of growing season and a number most gardeners are familiar with. But, unlike common annual garden plants, the green tissues on a pecan tree do not freeze at 32 degrees. Pecan leaves and shucks freeze at about 26 degrees which makes the freeze free days above 28 degrees (data reported by the NWS) a closer approximation of average length of the pecan growing season.        

    As you might expect, locations farther north had a shorter growing season than more southerly locations. The two most southerly locations (Chetopa and New Madrid) have the most summer heat. However, there seems to be east-west heat gradient among the 4 other locations that all lie approximately on the same northern latitude. Paola, KS is the hottest during the summer while Carlyle, IL  is the coolest.
    At each location, I checked on the development of two of our most popular pecan cultivars -- Pawnee and Kanza. Lets look at the photos, starting with Kanza.

     On Average, Kanza ripens a few days after Pawnee so I was little surprised to find shuck-split Kanza nuts all across the Midwest.  As you look at the photos you'll note that Kanza nuts look pretty much the same anywhere they are grown. The one exception was at New Madrid where the nuts were covered with black sooty mold that developed following a huge aphid outbreak.
    The one orchard I did not find Kanza fully shuck-split was located in a bottom-land orchard near Paola, KS. From the table above, you can see that Paola has the shortest growing season of all the sites I visited but this location gets plenty of summer heat. What's interesting is that just a few miles away and on top of a limestone ridge, Kanza nuts were fully split open.
    Now here's a valuable lesson. Macro-climatic conditions (as measured by the NWS) may be useful for predicting cultivar adaptation on a general level but micro-environmental conditions will determine the exact timing of pecan bud-break and nut shuck-split at any specific location.
    In the Spring and Fall, cold air flows like water down hill and accumulates in the valleys and low areas. This natural downhill movement of cold air is the reason we have areas in the landscape called "frost pockets".
    The cumulative impact of cold air movement into the bottom-land site near Paola means that things warm up later in the spring and they cool off sooner in the Fall than the nearby upland site. As a consequence, a location where cold air settles has a slightly shorter the length of growing season and a reduced number of cooling degree days. This movement of cold air also explains why the upland Kanza nuts were ripe last week while the bottomland Kanza nut were still a few days away from splitting shuck.

     Now let's look at the Pawnee photos (at left and below). Unlike Kanza, I found a wide range of ripening stages among Pawnee nuts across the Midwest.  At the warmest and most southerly locations, Pawnee was split wide open and had been split for quite some time. When I drove northwards into Illinois I found Pawnee was just starting to split shuck. This was exactly the kind of observation I was expecting to make on the trip.
   Locations with a shorter and cooler climate should ripen pecans later in the year.

     But then I moved into central Missouri and onto eastern Kansas. At these locations, I found that micro-environmental conditions impacted Pawnee nut ripening. The Columbia orchard is in an upland position while the New Franklin site is located in the Missouri river flood plain. The Pawnee nuts I saw in Columbia were similar in ripening stage to the Pawnee I saw in Illinois. But just down the road from Columbia at the Horticulture and Agroforestry  Research Center (HARC) near New Franklin, Pawnee was still tight in the shuck.
    In this case, Pawnee nut development at New Franklin was delayed in comparison to Columbia by two factors--position in the landscape and soil type. The HARC orchard lays at the foot of the river hills in the Missouri river flood plain--a perfect spot for cold air to settle. Pawnee trees at this location are also growing in a heavy clay soil. This type of "gumbo" soil warms so slowly in the Spring that bud-break can be delayed pushing back the entire nut development process.  
    When I arrived back in Kansas, I found that stage of Pawnee ripening mimicked the observations I made for Kanza at the same two orchards. Pawnee growing at the upland site in Kansas was split much like Columbia, MO and Carlyle, IL. At the bottom-land site in Paola the shucks were still tight just like the nuts I saw at HARC.
    In comparing Pawnee and Kanza across all locations this year, the ripening dates for these two cultivars were nearly similar at the four most northerly locations. In Chetopa and New Madrid, Pawnee ripened significantly earlier than Kanza. But every season is a little bit different. If I were to repeat this trip next Fall, I would probably find slightly different patterns of pecan ripening.

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.

Kanza production 2013

2013 Kanza Crop

     I've been recording the yield of a 3 acre block of Kanza pecan trees over the past several years. In 2013, we had a nice crop of good sized nuts with the yield bouncing back following two years of drought. The yield of for these trees over the past four years is given below.

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Year   Tree age   Yield (lbs/acre)
-----  ---------  ----------------
2010      15         1050
2011      16          899
2012      17          810
2013      18         1028
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    This winter, we will be thinning additional trees from this orchard according to our thinning plan.