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| Kanza, 30 Sept 2016 |
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| City Park, 30 Sept 2016 |
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| James, 30 Sept 2016 |
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| Mandan, 30 Sept 2016 |
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| Posey, 30 Sept 2016 |
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| USDA 75-8-5, 30 Sept 2016 |
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| USDA 75-8-9, 30 Sept 2016 |
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Pecan cultivars ripening on the last day of September
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A tree can produce too many pecans
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.
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Pecan cultivars that ripened in early October
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| Major, 4 Oct 2016 |
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.
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| 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.
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| Yates 68, 4 Oct 2016 |
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Early October flood on the Neosho
This week, parts of SE Kansas received over 12 inches of rain over 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.
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Hark has a thick shuck
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Pecan cultivars ripening in mid-October
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| Giles, 17 Oct. 2106 |
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.
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| Chetopa, 17 Oct. 2106 |
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| Greenriver, 17 Oct. 2016 |
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| Lakota, 17 Oct. 2106 |
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| Oswego, 17 Oct. 2106 |
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| Maramec, 17 Oct. 2016 |
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| Caddo, 17 Oct. 2016 |
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| Dooley, 17 Oct. 2016 |
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| Oconee, 17 Oct. 2016 |
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Fall fertilzation
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.
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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.
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.
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Testing out our harvest equipment
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.
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We need a good freeze to advance harvest
However, the forecast for the first week of November does not include any freezing temperatures.
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.
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Making plans to thin our Kanza block
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.
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Kernel appearance matters
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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.
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Stick-tights: When a pecan kernel doesn't develop inside
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.
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Pecan harvest rolls on
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View from the office
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.
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More than black spots on pecan kernels
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.
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What happens when Kanza over-produces
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.
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Stratifying pecan seed
The beginning of a new year usually inspires folks to make plans for the future. I can't think of any better plan then to plant more pecan trees. So the very first thing I did in 2017 was to start stratifying pecan seeds that I plan to grow into new trees this summer.
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Stratification is the method we use to promote uniform seed germination. The process involves getting the seed nut fully hydrated then storing the moist seed in temperatures between 32 and 40 degrees F (0 to 4 degrees C) for 90 to 120 days. I started the process of stratification by placing some Giles pecans (2016 crop) into a 5 gallon bucket (photo above right).
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I then added enough water to float the nuts inside the bucket (photo at left). To make sure the seed inside the shell becomes fully hydrated, I like to soak the nuts for 24 hours .
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To keep the nuts that float wet during the entire 24 hour soaking period, I placed a second 5 gallon bucket inside the first bucket and on top of the nuts (photo at right). By adding water to the upper bucket, the weight of the upper bucket presses down on the nuts below and keeps all seed nuts fully submerged.
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After 24 hours, I drained off all water from the seed nuts. As a precautionary measure, I added some Captan fungicide to the wet nuts and stirred the nuts around until each nut was coated with the white powder (photo at left). The fungicide will act to prevent kernel rotting fungi from destroying seeds during the cold stratification process.
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I use plastic storage boxes for seed stratification. I start by placing a layer of potting soil in the bottom of the box (photo at right). The potting soil is damp (not dripping wet!) and about 1.5 inches deep. By using damp potting soil, I ensure the nuts stay fully hydrated during the entire cold storage period.
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Next I add a single layer of nuts to the box (photo at left).
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I then add another layer of moist potting soil over the top of the nuts. At this point my small storage box was full and ready to be refrigerated. I you choose to use a deeper storage box, multiple layers of nuts can be added to the box. Just make sure to add potting soil between each layer of seed.
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One reason I like to use storage containers for stratifying seed is because the lids fit tight enough to prevent moisture loss during cold storage. I place a label on each box with the cultivar name and the date the nuts begin stratification (photo at left). To achieve uniform germination pecan seeds need at least 90 days of cold temperatures. I use a standard household refrigerator to treat the seed and set the temperature to 34 degrees F (1 degree C).
By April 2nd, these nuts will have had 90 days of cold treatment. However, I don't like to plant seed into pots until the danger of frost has passed. At my location, the average frost free date is April 20th. With an extra couple of weeks in the cold, these seeds should pop up quickly after planting.
By April 2nd, these nuts will have had 90 days of cold treatment. However, I don't like to plant seed into pots until the danger of frost has passed. At my location, the average frost free date is April 20th. With an extra couple of weeks in the cold, these seeds should pop up quickly after planting.
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In the eye of the beholder: Kanza and Pawnee
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.
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 andI find it refreshing to switch up a recipe by simply using a different pecan cultivar.
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