Another great day for harvest

    Today was another absolutely beautiful day for harvesting pecans. We broke out the old Lockwood pecan picker to harvest one of our cultivar trails (photo at right). This Lockwood machine may be over 40 years old but it still the best machine for harvesting the small, two-tree plots in this trial. Each cultivar is painted with a different color code to make identifying plots easy from the seat of the shaking tractor or harvester. Trees with yellow paint are Greenriver. Red and green paint on the same tree indicates a Chetopa while blue and white means Giles. There are 9 cultivars in this trial with each cultivar having a different color code. It definitely makes for a colorful orchard.

       When the Lockwood picker was designed back in the late 1960's, pecans were handled in burlap bags. Once the hopper gets full of nuts, we pause the machine, drop the out-feed gate, and the nuts come pouring out (photo at left). This system was originally designed to pour nuts into a burlap bag but we have refitted our Lockwood with a longer out-feed chute capable of  dropping the nuts into an portable elevator.

    The elevator lifts the nuts up and drops them into a waiting super sack (photo at right). This way, we can use a tractor for all the heavy lifting instead of getting a sore backs.
   We mounted the elevator on an axle and wheels to allow us to move it around the pecan grove.  A gas-powered,  electric generator provides the electricity needed to power the elevator.

The rush to harvest pecans is on!

   On this day after Thanksgiving, many Americans spent the day rushing about in huge crowds of people at the local shopping mall. But on this warm and sunny day, we spent the day rushing around the pecan grove harvesting nuts. In fact,  the entire river bottom was humming with the sounds of pecan harvest as growers throughout the area worked to harvest the 2014 crop.

   At the Pecan Experiment Field, we use a stick rake (photo above) to remove fallen limbs knocked to the ground by the tree shaker. Once the sticks are raked off the orchard floor, we use a pull-type harvester to sweep pecans up off the ground (photo at left).
   After putting in a long day of harvest today, I gained two impressions of this year's native pecan crop. Yields are below average and we are shaking out a lot of dead wood. These outcomes  are probably related to the several years of drought we've experienced recently and the late spring freeze of 2014.

Mid-November cold injury

Osage, 24 Nov. 2014

   Last week we experienced extremely cold temperatures for mid November. On November 18th, we recorded a low temperature of 6 F (the -14 C). So this week, I decided to check the condition of some of our mature, nut-bearing trees.
    Each photo that accompanies this post shows the bark peeled back on a fruiting shoot (on the left) and a vegetative shoot (on the right). The caption below each photo identifies the cultivar.
  

Kanza, 24 Nov. 2014

Chetopa, 24 Nov. 2014

Maramec, 24 Nov 2014

    In peeling back the bark of several cultivars, I found a range of cold
injury. Osage, which produced a light crop this year, had a healthy green color inside the bark. Kanza and Chetopa showed signs on internal browning while Maramec was severely injured by the cold.
     In looking at the Kanza shoots you will note that the fruiting shoot appears to have more internal browning than the vegetative shoot.  I noticed this same relationship between fruiting stress and cold injury with Pawnee last year. In contrast, Chetopa shoots seemed to have the same amount of cold injury regardless of shoot type.
    Both Maramec shoots displayed severe internal browning. However, the fruiting shoot appeared to have suffered greater cellular freezing.
    In years past, I have seen cold injured trees break bud normally in spring and set a good crop of nuts. Pawnee trees injured last winter produced a good crop this fall. It will be interesting to watch how cold injury in mid-November impacts flowering and fruiting next spring. I have the feeling that Kanza and Chetopa will overcome the damage they suffered and produce nuts next year. Maramec may be in trouble for 2015.

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.

Grafts survive cold snap

    When I woke up this morning the temperature outside had dropped to 6 degrees F (-14 C). For mid-November that's pretty darn cold. When I drove by some of my young pecan grafts today, I noticed some of the leaves were still frozen on the tree (photo at right). These leaves had frozen back on November 4th during our first hard freeze, but when leaves remain on the tree it indicates that those branches had not fully hardened off in preparation for winter before the cold weather hit. With the extreme cold this morning, did my young grafts suffer cold injury?

   To check for winter injury, I took my pocket knife out and cut into the main stem of the graft and peeled back the bark. Winter injury on pecan first appears as brown streaks in the  inner bark. The inner bark of this tree was healthy and green (photo a left). The two small, circular, brown spots you see on the inner bark are wounds caused by insects that feed on the stem last summer. 

    This young graft had several, small-diameter shoots at the top of the tree (see photo above). These shoots had developed in mid-summer as a result of a second flush of vegetative growth. This was also the portion of the tree that was still holding on to its frozen leaves.
    Were these shoots injured by the extreme cold? To check, I cut into the wood for look at the inner bark (photo at left). I found nice green inner bark. At this point in time, this Kanza graft looks in good shape.

   Early this year, I decided to top-work a few Jayhawk pecan trees to some new cultivars. When you graft such large trees, the scions grow extremely fast and tall. Vegetative growth can continue late into early-Fall and that new tender growth can be prone to winter injury. The photo at right is one of the top-worked trees I grafted last spring. The graft union is painted white and the scion grew a healthy five feet in height this past summer. Note that the branches below the graft have lost all their leaves while top of the new graft has leaves frozen in place. I needed to check this graft for cold injury.

   I cut into the stem of the new graft and peeled back the bark. The inner bark was still green and healthy (photo at left). No cold injury here.
  

Winter arrives in mid-November

    Last week we harvested a lot of pecans despite the below normal temperatures. Conditions were dry and the harvest machinery was working great. Unfortunately, 3 inches of snow fell yesterday and the grove was blanketed in white (photo above). It will take some time before the snow melts and the ground dries enough to resume harvest. In the mean time, we'll be in the barn running harvested nuts through the cleaner.  

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. 

Pickin' pecans

Harvesting Pawnee pecans

Shaking a Pawnee pecan tree

     What a great day for harvesting pecans. The weather was warm and sunny and all our harvest machines were operating perfectly (see photos). Unfortunately, the weatherman has forecast  a massive cold wave to push through the Midwest starting tonight. If we don't get much rain overnight, we'll be back to harvesting the rest of this week. But with high temperatures predicted to be only in the 30's (F), we'll need to break out the coveralls, warm hats and gloves and try to stay warm. It won't be as fun as it was today, but we need to beat the squirrels, crows, and deer to our nut crop.

Without a kernel inside, pecan shucks don't open.

    The Kanza cluster, pictured at right, contained four pecans. Three nuts had wide open shucks with pecans ready to fall from the tree. The fourth nut had a shuck that was still tightly closed and showed no sign of splitting open. In a previous post, I mentioned that a pecan weevil infestation can cause the shuck to remained firmly attached to the nut. However, in this case, there was no indication of weevil activity. Was this one nut just slow to open up or had something gone wrong inside the nut?   

   In the photo at left, you can clearly see that three nuts had normally split shucks while the fourth was still bound inside a closed shuck. The nuts emerging from split-open shucks had developed their normal shell color and were packed with kernel (note nuts cut in cross-section at the bottom of the photo).
    It took a little effort, but I could force the tightly held shuck off  the fourth nut. The shell inside had not yet developed normal shell color and I found a paper thin remnant of a pecan kernel inside.
   Back in August, the development of  kernel inside the stick-tight nut stopped during the water stage and a normal kernel never developed. Without a developing seed inside the shell, ripening hormones are not produced in the fall and the shuck does not open.

   

Hard freeze helps open pecan shucks

   On the first day of November, we had the first hard freeze of the season as temperatures dropped to 23 degrees. What always amazes me about the first hard freeze of the season is how quickly pecan shucks open up once all green shuck tissue is killed by cold temperatures. This year, I was able to photograph some pecan clusters two days before the freeze then again two days after the freeze.

   The first cultivar I looked at was Kanza. In the photo above, the Kanza nuts with green shucks had been split for over four weeks but the nuts were still tightly held inside. Freezing temperatures killed all green tissues and turned the shucks black. This rapid color change (from green to black) is caused by the formation of ice crystals that rupture cell walls and destroy cellular integrity. Once the cells are broken, the shuck loses moisture rapidly and dries quickly. What is fascinating to see is how quickly the  shucks pull away from the nuts following a hard freeze.  

    Ripening at the same time as Kanza, I also photograghed USDA clone 75-8-5 (photo above). Unlike Kanza, the green shuck of 75-8-5 pulls away from the nut exposing the nut inside. Once the freeze killed the shucks, 75-8-5 nuts looked ready to fall from the tree.
    The behavior of green shucks following shuck-split affects how fast a pecan dries on the tree. Before the freeze, I harvested a Kanza nut and a 75-8-5 nut and removed one half of their shucks. In the photo below you can see how loosely the 75-8-5 nut is held in the green shuck. In comparison, the Kanza nut is closely held by a much thicker-walled shuck. The Kanza shuck has actually trapped moisture on the outside of the shell preventing the nut from curing  (see photo below).
   If  I wanted to harvest pecans as early as possible, USDA 75-8-5 would be dry and ready to shake long before Kanza, even though both cultivars split shuck on the same date. Kanza really needed the Nov. 1st freeze to open up and allow the pecan to dry.