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. 

More than black spots on pecan kernels

   Over the past several years we have been making a special effort to prevent stink bugs from feeding on our nut crop. For the most part we've been fairly successful. However, we didn't start our stink bug control program early enough in the season to prevent black spots from developing on the kernels of very early ripening cultivars. The photo at right shows several Osage pecans damaged by stink bug feeding. As a very early ripening cultivar, Osage enters the dough stage at least a week before many of our standard northern pecan cultivars (Kanza, Pawnee, Major, Giles etc.). To prevent this type of kernel damage on Osage, we should have made a late July pesticide application in addition to our normal stink bug prevention program that begins during the first week of August.
    Stink bug feeding can cause more than just black spots on the kernels. Note the pecan in the lower right portion of the photo. A red arrow points to a large blackened area on a kernel half. When stinkbugs feed on pecan kernels, their digestive fluids kill a portion of the kernel leaving behind the characteristic black spot. However, during feeding, the stink bug can also introduce bacteria or fungi inside the shell. These organisms break down kernel tissue and cause large areas of the kernel to turn black. Ultimately, controlling stink bugs will prevent both types of kernel damage pictured above.   

View from the office

   Many of my regular readers might have wondered what happened to the stream of frequent posts that many have come to enjoy. No, I haven't run out of ideas to write about. I just haven't been able to type or take good photographs. Several weeks ago, I suffered a shop accident that required numerous stitches to my left hand. Needless to say the injury slowed me down but I was still able to drive a tractor and shake pecan trees. So, for much of December, my office became the cab of a tractor with my view being the trunks of native pecan trees (photo at right).
   My hand is well on the way of healing. I can once again take photographs with confidence and type blog posts for my readers. Look for more posts this week.   

Pecan harvest rolls on

   For many Americans, the Thanksgiving holiday weekend means four days of over-eating, shopping for Christmas presents and watching football. However, for area pecan growers, the holiday weekend has been a great time to harvest pecans. The ground is dry and nuts are easily shaken from the trees. Today, we harvested nuts from our native pecan plots (photo above). Judging from the sound of nuts hitting the roof of the shaking tractor, we will probably harvest an average sized native crop in 2016.    

Stick-tights: When a pecan kernel doesn't develop inside

    We were shaking some Kanza trees today, when I noticed a few bright green shucks still up in the tree. Most often its just one nut in a cluster of 3 to 4 nuts (photo at right). If you look closely at the still-green nut, you'll note that the shuck hasn't even split open. The fact is, this nut will never split open and will become what we call a stick-tight.

     I pulled some nuts off of our pecan cleaner's inspection table to find out what going on inside the nuts that remain stick-tights. In the photo at left, two stick-tights are shown next to two normal Kanza nuts. I cut each of the nuts in half to reveal what is inside the shell. The normal pecans had nicely filled kernels while the stick-tights had kernels that never fully formed.
     It is the maturing seed inside the shell that triggers normal shuck opening. Without a fulled developed kernel inside, the shuck will never open.
    What causes kernels not to fill out? In this case it is not clear. Stinkbug feeding can cause a similar lack of kernel development but the interior portion on the nut would be jet black in color. Disease is not the cause because the nut appears perfectly healthy. This lack of kernel fill is most likely due to a miscue in tree physiology. For some reason the kernel filling process was switched off  during the water stage of kernel development.

    The appearance of these kind of stick-tights at harvest is not exclusive to the Kanza cultivar. When we cleaned our Pawnee pecans, I found stick-tights  with a similar lack of kernel development (photo at right). Thankfully, the number of stick-tights we harvest is only a small fraction of the total number of nuts we collect each Fall. It just drives me crazy to pull stick-tights off the cleaning table and think--what did I do wrong? The answer is probably, nothing. I guess our pecan trees are just not perfect when it comes to filling out every kernel on the tree.   

Fungicides help reduce alternate bearing of pecans

   The photo above is a perfect illustration of the impact fungicide applications have on pecan leaf retention. This morning, I drove into the Pecan Experiment Field and noticed a stark difference between our trees (left of the lane) and our neighbors trees (right of the lane and across the fence). Our trees still had leaves on them.
    The difference in leaf retention wasn't due a difference between grafted trees and native trees. Trees on both sides of the lane are grafted. On the left are Posey and Pawnee trees while the neighbors trees are primarily grafted to Mohawk. The difference in fall leaf retention pictured above is entirely due to the application of fungicides made last summer to control scab. Our neighbor did not use any fungicides in 2016.
   Even though our primary goal in making fungicide applications was to control nut scab, fungicide sprays have the secondary benefit of keeping leaf diseases under control. It was the cumulative impact of several foliar diseases that caused early leaf drop in our neighbors orchard. 
    Long before the leaves drop from the trees, foliar diseases reduce the tree's ability to capture the sun's energy and convert that energy into carbohydrates. This usually happens in late summer, exactly at the same time pecan trees need the carbohydrates to fill out nut kernels.  The result is an exaggeration of fruiting stress during the current season and a weak return bloom the next.
   Over the many years of managing our pecans at the Experiment Field we have found that preserving leaf health with fungicide applications help reduce the intensity of alternate bearing. But remember, all the fungicides applied were aimed at controlling pecan scab. Improving leaf health and reducing alternate bearing is a welcomed bonus.     

Kernel appearance matters

   Even though I get great joy from watching young pecan trees grow and then set their first crop of nuts, the real reason I invested time and money in a pecan orchard is to produce pecan kernels for sale to the public. And the public has high expectations for pecan kernel quality. One of the reasons I've come to appreciate the Kanza pecan cultivar is that it always seems to produce a plump, light-colored, kernel (photo at right).     However, there are pecan cultivars that produce such unattractive kernels it makes selling those nuts difficult. Let me show you a few examples.

   Witte ripens very early and produces a good sized nut. What looks to be an outstanding northern pecan cultivar on paper is nearly impossible to sell to the pecan consuming public. Witte kernels are always deeply wrinkled giving the nut a shriveled appearance. The kernel also darkens quickly (not shown here). If a pecan kernel is unattractive, the consumer will never place a nut in his mouth. Flavor, no matter how outstanding, will always be a secondary cultivar attribute to most consumers.

    Mandan, a cultivar released in 2009, is a pecan that was promoted as early ripening and having high nut quality kernels. Mandan produces pecans with high percent kernel but those kernels are ugly. The nuts appear wrinkled with the underside of the kernel half sunken and hollow-looking (photo at right, blue arrow). On the tip of the kernel, an extra flap of skin looks unsightly (red arrow). For a cultivar that produces nearly 60% kernel, Mandan nut meats always look shriveled and unappealing.

  A different kind of ugly kernel comes in the form of mottled or blotchy kernels (photo at left). The degree of blotching  seems to vary with the year. Pawnee, Faith, Gardner, Jayhawk and Giles are most prone to develop a mottled kernel color. Even though Pawnee has become one of our most desirable cultivars because of its large nut size and early ripening, I'm starting to limit its propagation on my farm. Between scab susceptibility and blotchy kernels, the risks associated with growing additional Pawnee trees have become too great for me.       

Making plans to thin our Kanza block

    Readers of this blog may recall that we have a block of Kanza trees at the Pecan Experiment Field. In 2012, I drew up a tree thinning plan to remove a portion of the trees in this orchard to allow the remaining trees more room to grow. We took a progressive approach to thinning the orchard. We removed trees gradually, several each year, in areas where trees were beginning to crowd.
    This Fall, when I walked out to the Kanza orchard to check on tree spacing, I noticed that most areas that have not been thinned yet had limbs that were beginning to touch (photo at right).  Following the 2016 harvest season we will be taking out more trees, this time more trees than we had in previous years.

   I also checked areas in the Kanza block that had been thinned in previous years. Here I found the trees to be well spaced with plenty of light penetrating all portions of the canopy (photo at left). Eventually the entire block of Kanza trees will be thinned to this spacing (43 feet by 43 feet).  

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.

Testing out our harvest equipment

    Last summer we made some improvements to our harvesting equipment. To test how those mechanical modifications would hold up during harvest, I decided to shake some early maturing cultivars that had already dropped a large portion of their crop on the ground (photo at right).  We started with Colby trees today, and will move on to Osage and Canton tomorrow.  

    My main concern was to make sure the harvester would pick pecans the way we designed the machine (photo above). As many growers have seen during field days, we have modified our 8090 Nuthustler pecan harvester by making major changes to the drive line, nut elevator system, cross auger, and cleaning chamber. We even added a sweeper wheel to the harvester. This year we replaced the conveyor chain inside the machine. Rather than use the webbed chain as provided by the manufacturer, we inserted what is known as welded selvage belting in its place. We are hoping the selvage belt will last longer than the original chain and help sift out some of the dirt picked up by the harvester.

Pecan maturation after shuck split

   The date a pecan cultivar splits its shuck is an important indicator of how well that cultivar is adapted to the climate at a particular location. However, pecan maturation does not stop at shuck split. A pecan does not become fully mature and achieve full flavor until the kernel dries down to under 12% moisture. To demonstrate how pecan kernels change as they dry, I harvested some Stuart and Kanza nuts (photo above). The Stuart nuts were loose in the shuck but the shuck had yet to split open. The nuts inside the Stuart shucks are still at their maximum moisture content. Kanza nuts split shuck 3 weeks ago and the nuts inside have begun to dry down.

    When I cracked open both cultivars I had lots of trouble producing full kernel halves (photo at right). Both kernels were tight against the shell so that when I  cracked the shell  I also broke the kernel. In handling both kernels, I could feel the moisture on my fingertips. The Stuart kernel was really wet, giving the kernel a sticky and rubbery feel. In contrast, the Kanza kernel was smooth but still slightly rubbery.
   The obvious difference between these two cultivars was kernel color and appearance. The high moisture Stuart nut was white and covered in brown fuzz. The shell packing material in the dorsal groves was a sticky mess. The Kanza kernel appeared to have normal color and the packing material fell free of the kernel.
    Looking at these two pecan cultivars gives us a pretty good idea of how pecan kernels mature after shuck-split. The drying process helps the kernel separate from the shell and all internal packing material. The outside of the kernel dries to a golden brown color. Full pecan flavor is achieved only when kernels dry down to less than 12% moisture.
  

Fall fertilzation

    Its finally dried up enough to allow us to make our regular Fall application of nitrogen fertilizer. The weather forecast calls for a 40% chance of very light showers tomorrow. So today, we spread 100 pounds of urea fertilizer over the entire orchard floor. One hundred pounds of urea equals 46 pounds of actual nitrogen. I'm hoping for just enough rain (or even a heavy dew) to help move the applied nitrogen into the soil profile.
   In the past, many growers have asked how I handle the fertilization of young trees. As the photo above shows, my approach has been to use conventional fertilizer spreading equipment to cover the entire orchard floor with fertilizer. Even though the trees look small on top, these 4 to 6 inch diameter trees have root systems that extend outwards twice the height of the tree. By spreading the fertilizer over the entire grove, I hope to encourage additional lateral root growth to help the tree be even more efficient in mining the soil for water and nutrients.
    Of course, the added nitrogen will also stimulate the ground cover to grow like crazy. But the way I look it, I'm actually growing a green manure crop right in the orchard. Every time I mow the ground cover, I'm adding tons of organic matter back to the soil. Soil organic matter helps build soil structure, improves water availability, and makes micro-nutrients (including zinc) more available to the tree.
   

Pecan cultivars ripening in mid-October

Giles, 17 Oct. 2106

    Last week the Neosho River flooded our pecan grove. As soon a the flood receded, we received a day-long rain storm. Water and mud was everywhere. Today was the first day I could get out into the field to check on nut development. Since its been two weeks since I last checked for cultivars with shuck split, I found many pecan cultivars had ripened since early October. Photos of those cultivars ripening in mid-October are at right and below.
    Note that Giles, Chetopa, Maramec, Caddo, and Dooley have scab lesions on their shucks. Scab has reduced nut size and prevented normal shuck-split of Dooley especially. Greenriver, Lakota, Oswego,  and Oconee are scab free.

Chetopa, 17 Oct. 2106

Greenriver, 17 Oct. 2016

Lakota, 17 Oct. 2106

Oswego, 17 Oct. 2106

Maramec, 17 Oct. 2016

Caddo, 17 Oct. 2016

Dooley, 17 Oct. 2016

Oconee, 17 Oct. 2016

Hark has a thick shuck

   Between the flood earlier this week and a soaking rain today, its been difficult to get out to the Pecan Experiment Field to check on pecan ripening. However, I was able to collect some nut samples from trees on my farm. When I collect samples, I like to pull nuts right out of split shucks to ensure that I get the right nuts in each sample bag. While collecting samples, I was surprised to find Hark has an extremely thick shuck (photo at right).

  But Hark is not the only pecan cultivar with this kind of thick shuck. I also collected nuts from Kanza and Yates 68 and found thick shucks covering both cultivars (photos at left).

    All of three of these cultivars (Hark, Kanza, and Yates 68) have a common parent--Major. The photo at right shows Major pecan also surrounded by a thick shuck. Close inspection of these four cultivars reveals other common cultivar characteristics. The nuts appear more rounded than many pecan cultivars and the outside of the shells are dotted with fine black speckles. When these thick shucks split, they do do not pull back away from the nut. This results in nuts being firmly held in the tree until a hard freeze kills the shuck and the tree is given a good hard shake.

Early October flood on the Neosho

   This week, parts of SE Kansas received over 12 inches of rain in a 3 day period. The Neosho quickly filled and has now spilled over it banks, flooding both the Pecan Experiment Field and surrounding native groves (photo above). The National Weather Service is predicting only a moderate flooding event that should last about three and a half days. Fortunately, we had not yet made our regular Fall fertilizer application. If we had spread nitrogen on the grove earlier this week, it would have ended up down in Grand Lake instead of helping our trees. After the flood waters recede and the orchard floor dries up, I'll be checking the weather forecast closely to choose the best time to spread some fertilizer later this month.

Pecan cultivars that ripened in early October

Major, 4 Oct 2016

    I was back out in the orchard looking for more cultivars with split shucks. Today, I found just three. Major is one of our standard northern pecan cultivars and a cultivar that has been around since 1908. Jayhawk is a seedling of Giles and Yates 68 looks to be a hybrid of Major and Posey.
   The shucks of a Major nut split along the suture lines but hardly open up  (photo at right). It will take a hard freeze to kill the green shucks before Major nuts are released from the tree.

Jayhawk, 4 Oct 2016

    Jayhawk and Yates both yield well but their kernels have major defects. Jayhawk kernels are often mottled with light brown spots over the straw-colored nut meats. Yates 68 kernels turn dark quickly after harvest in a fashion similar to Posey.

Yates 68, 4 Oct 2016

A tree can produce too many pecans

     Precocious and Prolific--Two words that pecan breeders like to throw around in describing their new pecan cultivars. A precocious pecan cultivar is one that starts to bear nuts at a young age. A prolific pecan cultivar produces a lot of pecans. The tree pictured at right is currently known as USDA 75-8-5. This clone has been touted as both precocious and prolific and you can see by the drooping limbs that this young tree is loaded down with nuts. However, excessive crops present their own set of problems. 

    In previous years, we have attempted summer tree shaking this cultivar as a method to reduce the excessive crop load. Unfortunately, summer shaking does not work well with this clone. In the photo above-left, note that the nut crop is held on the ends of long slender shoots. During a summer shake, these limbs just dance around and very few nuts are dislodged.

   The problem with over production becomes evident at harvest. For the photo above, I cut open three nuts pulled from the USDA 75-8-5 tree and compared them to three nuts harvested from a nearby Kanza tree. Both these cultivars ripened at about the same time but the cross-sections of the USDA 75-8-5 nuts reveals the impact excessive cropping has had on kernel fill. The USDA clone has thin kernels, lots of internal air pockets and the kernel was unable to fully compress the partition between kernel halves. But the real troubles will come this winter and next year. 75-8-5 has set itself up to be damaged by cold winter temperatures. If not damaged by cold, the tree will be unable to set a full crop of pistillate flowers next spring.
   The moral of this story is that heavy nut yield at a young age usually precedes a future of alternate bearing and cold injury. In testing new cultivars, I look for a tree to start bearing early but to build yield slowly always maintaining excellent kernel quality.

Pecan cultivars ripening on the last day of September

Kanza, 30 Sept 2016

    I found several more cultivars that have split open their shucks today. Kanza was split which seems earlier than normal. In contrast, the other cultivars I found with shucks split seemed to be ripening right on schedule. Photos at right and below.
 

City Park, 30 Sept 2016

James, 30 Sept 2016

Mandan, 30 Sept 2016

Posey, 30 Sept 2016

USDA 75-8-5, 30 Sept 2016

USDA 75-8-9, 30 Sept 2016

Scab masks actual ripening date

    Over the past two weeks I've been trying to make a photographic record of when pecan cultivars ripen at the Pecan Experiment Field. But when it came to determine a shuck-split date for Hirschi, the susceptibility of this cultivar to pecan scab makes it nearly impossible  to tell when the shuck opens normally. In the photo at right a cluster of Hirschi nuts is covered with scab lesions. two of the nuts have tightly held shucks while the third appears to be opening up.

  On the same tree, this cluster of Hirschi nuts has less scab covering the shuck but the shucks have yet to open (photo at left).

    Five days later I went back to look over Hirschi to see if the nuts had opened up and I found at least one nut cluster with normal looking shuck split (photo at right).
    Pecan scab interferes with normal shuck opening. Based on what I've found by watching Hirschi this fall, scab can both delay and inhibit shuck split. From past experience I know that Hirschi ripens early, but this year's true shuck-split date for this cultivar was masked by scab covered shucks.