Northern Pecans

Vivipary: A ten dollar word that describes the premature germination of a pecan in the shuck during the Fall of the year. Normally, pecan seeds are fully dormant in October and require a 90-day chilling period to stimulate germination. However, a heavy nut crop and unusually warm, moist, weather conditions during shucksplit can trigger vivipary. In the photo at right, the yellow arrow points to a pecan root emerging from a recently harvested pecan. When a sprouted pecan is harvested and dried under normal harvest conditions, the little root dies and the embryo inside the shell decays. Ultimately, embryo rot totally destroys the value of the kernel.
Fortunately vivipary is a rather rare phenomenon in northern pecan areas. This year I've found only 2 sprouted nuts among the thousand of nuts I've collected for evaluation this winter. Most years I never see vivipary at all.

Over the past several weeks I've be photographing pecan shuck-split and collecting nut samples. If you look at enough nut clusters like I do, you will usually come across a cluster that has one nut that doesn't seem to split at the same time as all the others (yellow arrow, photo at right). In fact, the shuck stays green and tight all the way until first Fall freeze and never opens. Whats going on here?

The cluster pictured above yielded four nuts (photo at left). Three of the nuts were easily removed from split shucks. The forth was tightly held inside a green shuck.

I cut each nut in half to inspect the kernel within (photo at left). The three normal pecans were fully packed with kernel. The nut with the tight green shuck had the remnants of a kernel that stopped growing at the water stage (early August). Judging from the color of the unfilled seed coat, this kernel was aborted by the tree for some unknown physiological reason. If the seed coat had been colored jet black, the nut would have been the victim of stinkbug feeding. If the nut had been hollowed out by pecan weevil, I would have found worms inside the green stick-tight. In each case, lack of kernel fill prevents the pecan shuck from opening properly.

Stuart, 23 Oct. 2017

Well adapted pecan cultivars are ones that split their husks well before the average date of first fall freeze. In our area of SE Kansas, the average date of first fall freeze is October 21.
Today, I photographed shuck-split of our latest ripening pecan cultivars currently under evaluation at the experiment station. Stuart is an old southern cultivar that might be the widest recognized cultivar in the world (photo at right). However, Stuart is not well adapted to our area. Most years, Stuart has fuzzy and dry tasting kernels, indicating that this cultivar did not have a long enough growing season before temperatures start to turn colder in the Fall

Oconee is a newer USDA cultivar that produces a beautiful nut (photo at left). However, like Stuart, Oconee ripens too late for us. Oconee is scab resistant and would make an excellent choice for growers with a longer growing season.

By mid October, you can really see the difference fungicide applications make towards preserving pecan leaf health. This past year we made three fungicide applications to all of our orchards at the Pecan Experiment Field except for a five acre block of native trees that did not receive any pesticides.

The photo at above shows our fungicide treated pecan trees in mid-October. The leaves on these trees are still healthy and green. Healthy leaves capture energy from the sun and covert that energy into carbohydrates. Carbohydrates are then used to fill this year's pecan kernels and promote pistillate flower production next Spring. Maintaining healthy foliage throughout the growing season is the best way to reduce a pecan tree's natural tendency for alternate bearing.

Now look trees that did not receive fungicides during the growing season (photo above). By mid-October, some of the native trees had lost most of their leaves while most had taken on a bronzed appearance. These trees are already shutting down for winter. Lesser amounts of carbohydrates are created by damaged foliage and that limited supply of energy is totally directed towards filling this year's crop of nuts. This leaves little of no energy for pistillate flower formation next year. Unchecked pecan foliar disease ultimately accentuates the alternate bearing pattern.

Pecan diseases not only impacts leaf health but they can have direct effects on nut yield. The photo at right shows two clusters of Stuart pecans. The cluster on the left is covered with scab. On the right, the nuts still show signs of scab infection but to a much lesser degree. All of these nuts appear to be splitting open but the heavily infected nuts are one half the size. Pecan scab causes yield losses in three ways; early nut abortion, reduction in nut size, and a reduction in percent kernel.
The primary reason we apply fungicides to pecan trees is to control pecan scab. However, the secondary impacts of disease control on leaf health is equally as important. The introduction of pecan scab resistant pecan cultivars will make disease control easier but does not eliminate the need for fungicide applications. The control of leaf disease, especially during wet summers, is important for maintaining tree health and productivity.

After a couple of hard frosts over the weekend, we began harvesting pecans today (photo above). Although the shucks of all our cultivars have split, only the earliest ripening pecans were dry enough to harvest. Pecans, like all grain crops, should be less than 12% moisture at harvest so that they can be stored without danger of molding. Pecans harvested at a higher moisture content must be dried with forced air to prevent spoilage (again just like grain crops).
Today we harvested Osage, Jayhawk, Shepherd, Norton, Henning, Grotjan, Canton, and USDA 64-11-17. The tree being harvested in the photo above is Osage. All of the cultivars harvested today split their shucks a month ago in late September. The first day of harvest is also a good day to work out potential problems with our harvesting equipment. Thankfully, everything ran smoothly!

   While harvesting this year's pecan crop, I spotted a few nuts that had their shells broken open by one of the many critters that feed on pecans (photo at right). By just looking at the damaged nuts, I can tell the which pest caused the damage.
    A woodpecker caused the deep narrow hole in the nut labeled "A". With their sharp, narrow bill, woodpeckers punch a hole through the shell and feed on the kernel inside. Woodpeckers carry off small native pecans and cache them in tree voids for later consumption. Since they can't carry off large, thin-shelled nuts they simply take a quick bite before getting back to work stealing native pecans.
   Mice will climb up into trees and start gnawing into pecans as soon as the shucks split open. You can always spot a mouse damaged nut by the neat round hole they chew into the side of the shell (pecan "B"). They usually make the hole just large enough to poke their head into the shell and clean out every morsel of pecan kernel.
    A nut with a large irregular cracked hole was attached by a bluejay or crow (pecan "C"). These birds have large beaks that they use to pound open the shell. Often the nuts are broken in several pieces but they always eat the entire nut kernel inside.
Wildlife can eat a significant proportion of a pecan crop so its always important to harvest as quickly as possible. The list of critters that eat pecans include not only the three pests described above but also includes squirrels, raccoons, deer, coyotes and turkeys.

Kanza pecans, 2 Nov. 2017

   I don't think I've ever seem pecan trees hold on to their leaves like this year. During most years, we get a hard freeze in early November that causes pecan leaves to drop off the tree in just a few hours. Not this year.
    Temperatures dropped to 27 degrees (F) on a couple of occasions in late October which froze leaf blades but did not kill leaf rachii (photo above). The result of this weather pattern has been that shucks have opened up but the leaves have remained in place (even with frost burned leaflets).
    We have harvested several pecan cultivars this week but have found that the semi-green leaves that cover the ground after tree shaking has made harvest by machine a lot less efficient. It seems that the machine is having a hard time digging out pecans from the still leathery leaves. After a hard freeze (less than 26 F), leaves turn crispy dry and are ground up by the harvester.
    In time, our harvest problems will pass as colder temperatures are surely on the way. However, a second trip over the orchard with the harvester later this fall will yield far more nuts than in previous years.

We've been working our way through harvest picking up nuts in a various research plots. Last week we harvested Pawnee (photo at right) and I was pleased to see that summer shaking really paid off in terms of nut quality this Fall. This year's Pawnee nuts are some of the best we've every raised.
Pawnee has become a popular cultivar in northern pecan states because it ripens early and it produces large, thin-shelled nuts. With a good scab control program and crop load management, Pawnee can be a reliable income producer.
However, we have experienced one problem in growing Pawnee that is rarely if ever mentioned--Pawnee nuts do not fair so well when harvested mechanically.

The shells of Pawnee nuts are so thin that they often get cracked during harvest operations. I collected a few nuts from the cleaning table to show you what I mean. The majority of Pawnee nuts come through harvest fully intact (first 3 nuts in top row, photo above). Many nuts get cracked but the shell still covers the nut meat (top right nut, above). However, about 5% of the Pawnee nuts that come across the inspection table are cracked open, exposing the nut meat inside (nuts in bottom row, above). Sellable pecans must have intact shells to protect nut meats from contamination. When we sort our Pawnee nuts, any nuts with exposed kernel are thrown off the table.
Although consumers prefer nuts with paper-thin shells, they also demand a clean wholesome product. I have come to the realization that pecan cultivars that produce nuts with greater than 56% kernel will suffer signicant nut losses due to mechanical harvest using current equipment. This observation is something I'll keep in mind when evaluating the nuts produced in our breeding program.

We've been working hard at harvesting the 2017 pecan crop and I was struck by the obvious impacts pecan scab infection has had on some of our pecan cultivars. At the research station, we have a block of Giles and Chetopa trees, two scab susceptible cultivars. For each cultivar, I collected a nuts from the harvester and arranged them by size for a photograph.

    Each photo shows 3 normal sized pecans in the top row compared to scab-effected, smaller nuts in the bottom row. Although both cultivars showed signs of yield loss (smaller nuts) from scab, Giles looks harder hit.
   Looking back at our pecan scab control program in 2017, I think we made an error in waiting for the appearance of pecan nut casebearer before making our first scab spray. As it turns out, casebearer never developed to a damaging level but pecan scab got a good start on our nut crop in early June. I'm becoming convinced that I need to switch our pest control priorities. Next year, I'll time our June pesticide applications based on scab. If that means applying an insecticide a little early for casebearer, so be it. I'll just have to chose a long residual insecticide like Warrior or Intrepid to handle casebearer.

When we were harvesting a cultivar trial, I came across a plot of four Major trees that were fairly uniform in size and all bearing a good crops (photo at right). These trees were field grafted back in 1985 to Giles seedling rootstock trees. The grafts were placed at 18-24 inches above the soil surface and after 30+ years you can still see the graft union on each tree (note the abrupt change in bark texture).

    As I walked down the tree row, I noticed significant differences in the diameter of the rootstock as compared to the trunk diameter of the scion (photos above). For tree "A", the Giles rootstock has over-grown the Major scion. Tree "B" has a smooth transition between rootstock and scion. Trees "C" and "D" are more typical of trees grafted with a Major top--the scion overgrows the rootstock.
    Major is a vigorous growing tree, often producing the largest tree in a planting of several cultivars. That's why it so common to find Major scions overgrowing their rootstock. However, I wanted to show you these photos to make two points. First, no matter the seed source for the rootstock, there will always be variation in growth among rootstock trees. Each pecan rootstock tree has a unique genetic composition created by a known mother (in this case Giles) and a unknown father (pollen blown to the stigma on a puff of wind). This variation may cause differences in the appearance of a graft union but it appears to have little impact on the scion's performance and yield.
    The second point I wanted to make is that is not that critical to plant a particular seed source to grow rootstock trees. In northern pecan areas, you should use seed from either local native trees or nuts produced by a northern cultivar. The resulting trees will have the best cold hardiness for your location. Many years ago, we had some Giles trees growing at the research station that had been propagated by a southern nursery that used a southern pecan cultivar for growing their rootstock trees. In 1989, temperatures dropped to -26 F (-32 C) in mid-December. The Giles tops survived the cold but the rootstock portion of the tree was killed by the cold. With a dead root system, these tree had to be removed.

Kanza 2017

One of the reasons Kanza has become a popular pecan cultivar among consumers is that it shells out so well. After cracking Kanza nuts in a mechanical cracker then blowing out the shells with a single stage air leg, Kanza yields a high percentage of free kernel halves (photo above). Once all the free halves are separated out, it is very easy to remove attached shell fragments to extract the rest of the kernels.


Major 2017

I've been cracking several cultivars in my Savage air-cracker and have come to the conclusion that the shelling quality of Kanza nuts is probably inherited from its Major parent (Kanza resulted from a cross of Shoshoni and Major). The photo above shows a sample of Major nut processed using the same equipment I used to crack my Kanza crop. Even with a thicker shell, Major nuts crack out cleanly producing a large number of free halves. This got me thinking.

USDA 64-4-2

I grabbed a sample of USDA 64-4-2 which originated from a cross of Choctaw and Major. Cracking and blowing this sample yielded a high percentage of free halves. Nuts of 64-4-2 are not as round as Major or Kanza but the shelling quality was impressive.

KT143

Next, I cracked a sample KT143, a selection from my breeding project that originated from a cross of Pawnee and Major. Once again, I found excellent shelling quality.
Kanza, USDA 64-4-2, and KT143 share one thing in common. All three cultivars have Major as their female parent. And after looking a my cracked sample of Major, I'm convinced it is Major parentage that that makes these pecan cultivars such good crackers. I'm also convinced that producing pecan cultivars that are easy to shell will make my customers for cracked pecans very happy and willing to pay a premium these nuts.

On my farm, I established our pecan orchard in a field that is located within the Neosho River flood plain. The soils in this field are mostly Hepler silt loam with small areas of Osage silty clay. This area of the farm is subjected to occasional flooding. However, I couldn't resist planting pecans around my home, located up the hill just a few hundred feet from the main pecan grove. The soil at the home site is a Cherokee silt loam; a soil that was formed from river-deposited silt during the melting of the last ice age. This soil (and my house) is not subject to flooding.

By planting trees in both bottomland and upland positions in the landscape, I can see how site selection impacts pecan performance. The photos at right and above show Jayhawk and Kanza nuts collected from similar aged trees. Within each photo, the two nuts on the left were collected from trees growing in the floodplain. The two nuts on the right were harvested from upland trees. In both photos, the nuts grown in the river bottom are visually larger than the nuts collected on the upland. Sample weights (grams/nut) confirmed what my eyes could easily see (table below).

--------------------------
Site       Jayhawk Kanza
--------------------------
Bottomland   7.34 6.77
Upland       6.31   6.19
--------------------------

I cracked out several nuts from each tree (photos at left and below). Of course, the larger nuts from the bottomland had larger kernels. However, what I was looking for was differences in kernel plumpness.

With ample rainfall falling during the kernel filling period this year (August 2017), upland pecan kernels were just as full as kernels collected in the river-bottom.
   So why the difference in nut size?   It all comes down to internal differences in soil profiles. The surface layer of Hepler and Cherokee soils are very similar; both are described as silt loam. The important difference comes deeper in the soil profile. If your dig deep into the Hepler profile, you'll find the that the soil comes heavier (more clay) with depth. But the transition is gradual with no abrupt changes in soil texture. In contrast, the Cherokee soil has about 14 inches of silty loam topsoil which abruptly changes to a firm clay subsoil.
     An abrupt change in soil texture has major impacts on the movement of water within the soil profile. Both Hepler and Cherokee are slow to drain after periods of wet weather. However, the clay pan found in the Cherokee soil creates what is known as a perched water table. Water moves so slowly into the subsoil that it stacks up in the topsoil creating a zone of super saturation. A perched water table causes the soil to lose vital soil oxygen which can lead to tree root death. Tree growing in soils with a perched water table typically end up developing shallow root systems and a pecan tree with shallow roots has a hard time competing for water during hot dry periods.
An abrupt change in soil texture between the topsoil and subsoil also impacts the movement of water upwards during dry periods. Surface evaporation and plant transpiration remove water from the upper portions of the soil. As the soil dries out, water moves by capillary action upwards through the soil. However, a prominent boundary layer, like a clay pan, will block the free flow of water by capillary action from deep in the subsoil. The result is a soil that tends to be "droughty".
   A soil with a strong boundary between topsoil and subsoil does not provide a healthy rooting environment for pecan trees. A perched water table in the spring limits root growth while soil water is held unavailable in the subsoil during the hot summer. Young pecan trees respond to upland soil types by producing smaller nuts. As trees on upland sites grow older, you'll find that trees becomes stunted, upper limbs may start dying back and nut production becomes limited and erratic.
   My main pecan orchard is located in the river bottom, where pecan trees thrive. The trees around the house will never be commercially viable but that's not why I planted them. I just enjoy looking out the window every morning and seeing beautiful pecan trees.

Stuart nuts at shuck-split

Stuart is one of the oldest and most widely know pecan cultivars. The tree had its origins in a seedling orchard planted in 1874 outside of Pascagoula, Mississippi using nuts procured from Mobile, Alabama. The tree gained local notoriety for excellent nut production. In 1893, a severe storm blew the original tree down. Fortunately, the tree re-emerged from a root sprout and the tree began bearing nuts again by 1902.
The first attempt to graft Stuart was largely a failure. In 1886, sixty grafts were attempted but only one grew successfully. Graft failure was all too common during the late 1800's as nurserymen used grafting techniques commonly used for fruit trees when trying to propagate pecans. However, by the early 1900's, grafting techniques specifically developed for pecan improved success rates dramatically. From the 1920's to the 1950's Stuart quickly became the dominant cultivar planted across the southeastern United States.

Stuart grown in SE Kansas 2017

But how did Stuart migrate northwards? The popularity of Stuart in the south was largely driven by outstanding yields and scab resistance. Every pecan nursery began propagating Stuart and trees became so widely available that they were ultimately promoted for planting outside traditional southern pecan growing areas. For a tree from the deep south, Stuart has excellent cold hardiness enabling Stuart trees to grow and thrive in northern pecan areas. However, it was soon discovered that northern climates do not provide a long enough growing season to properly mature nuts. Our 2017 crop of Stuart nuts contained roughly 50% stick-tights (photo above).

Poorly formed Stuart kernels

   A more common indication that Stuart is not adapted to northern climates is the incomplete development of kernel inside the shell (photo at right). Northern-grown Stuart nuts are usually fuzzy and shriveled. In addition, kernels are hollow and lack an good oily taste.
    No additions of water or fertilizer will ever alter the fact that Stuart will never make a decent kernel in northern areas. Stuart requires a longer growing season than northern pecan areas can provide for proper kernel development.
   One of the most interesting artifacts of the popularity of Stuart is the large number of Stuart seedlings that can be found growing all over the US, even in northern areas. During the Great Depression and war years (1930's and 1940's), pecans were a popular stocking stuffer for Christmas. The majority of gift basket pecans at that time were Stuart nuts and some of those nuts found there way into backyard gardens to eventually sprouted into trees. Today, you can find massive 90+ year-old trees that produce a blocky shaped nut that looks a lot like a Stuart nut but is generally smaller in size. These seedlings also produce nuts that struggle to produce quality kernels in northern climates just like the mother Stuart tree.

Every year I learn something new about native pecans. This past summer (2017), the branches of our native trees were hanging low with, what I thought, was a heavy nut crop. However, this past year our native trees fooled me. The limbs were weighted down with a huge leaf crop that hid a below average nut crop.
It was only when we began shaking trees, that we discovered the true nature of the 2017 native crop.

     For 37 years we have be recording the yields from 6, one-half-acre plots of native pecans. The 2017 yields are presented in the table above (numbers listed in Lbs.). The half-acre plots are labeled A thru F. We always harvest each plot twice; the first time in mid November and then again in late December. The weight of nuts collected at each harvest time is listed above.
    The 37 yield average yield/acre for these plots is 1150 lbs. The 2017 crop averaged 798 lbs./acre or 30% below average. What was interesting about the 2017 harvest was that we harvested almost one third of the crop (32%) during the second harvest. Prior to 2017, second harvest yielded 15% to 20% of the total crop. Why the difference in 2017?
    I blame the heavy leaf crop. During the first harvest, our pecan harvester had a tough time digesting all those leaves. A lot of nuts ended up riding on a stream of leaves and getting blown out of the back of the machine. When we went back for the second harvest, the leaves had been chopped up and partially broken down by our first harvest operation. During the second pass over the field, the harvester could easily process the ground up leaves and orchard floor was swept clean of nuts.
   A below-average nut crop and an above-average leaf crop in 2017 is a sure sign that the potential for the 2018 native crop will be huge.

Harvesting a young orchard

Frequent questions new pecan growers have usually revolve around questions of when and how much young pecan trees start to bear nut crops. Back in 2002 we planted one-year-old Colby pecan seedlings to start a new block of trees. Most of these trees were grafted in 2005, with every tree in the planting successfully grafted by 2007. We grafted three cultivars; Faith, Gardner and Lakota. The trees produced a handful of nuts by 2010 and as the trees grew larger nut production steadily increased.
By harvest time 2017, the trees in this orchard averaged over 7 inches in diameter and were producing a full crop of nuts. Lets take a look at this year's yield data.

This field of young trees contained 32 trees of each cultivar. We harvested each cultivar separately and then calculated yield per tree. In the chart at right, I list the average yield per tree and present a measure of the variation in yield observed between trees grafted to the same cultivar (mean yield +/- standard deviation).
Twelve to fourteen pounds of pecans per tree doesn't sound like a lot of pecans but, when added up on a per acre basis, the income generated by these young trees is significant.
The trees in this orchard were planted at a density of 27 trees per acre. This means that Gardner produced 327 lbs/acre, Faith produced 378 lbs/acre, and Lakota 359 lbs/acre. I sold these nuts for $3.00 per pound which translated to a gross return that ranged from $981 to $1134 per acre depending on cultivar. That's not bad for a 15-year-old pecan orchard.

    Winter has returned with a few inches of snow and bone chilling cold temperatures (photo above). So far this month, we have dropped to -3 degrees F (-19 C) and I've been wondering if we will see any cold damage displayed this coming Spring. Two types of pecan trees are most prone to winter injury: Vigorously growing grafts made last year and mature trees that produced too many nuts last Fall.
    For graft injury, it doesn't seem to matter which cultivar was grafted but rather, how late a graft grew into the Fall. Pecan shoots that don't harden off before a hard freeze seem to suffer the greatest amount of shoot dieback.
    Pecan cultivars that over-produce and have some southern blood are the most prone to suffering winter dieback. Shoshoni, Chickasaw, and Mohawk are cultivars we no longer grow because of over- production and subsequent cold injury. Last year, we made sure to summer shake our Pawnee and Lakota trees to prevent over-cropping and limit the possibility of winter injury.
    Thankfully, we have finished harvesting the 2017 crop and we are now cleaning the last few super sacks our pecans in a heated barn.

Greenriver kernels, 2017

Last summer we thinned the nut crop on several pecan cultivars including; Pawnee, Lakota, Faith, Gardner, and Kanza. Later, when we harvested the nuts from these cultivars, we found good to excellent kernel quality inside. However, after cracking open this year's Greenriver nuts, it looks like we should have thinned the crop on this cultivar also.
The photo at right illustrates the type of kernels I found inside our Greenriver nuts. About 25% had darkened kernels and another 25% had kernels that where somewhat hollow inside.

Oswego kernels, 2017

Oswego originated as a seedling of Greenriver. The nuts produced by Oswego are very similar in size and appearance to its parent. However, when I cracked a sample of Oswego nuts I found the kernels to have better color and nut fill (photo at right).
Why the difference? It boils down to crop load. At the Experiment Station, Greenriver and Oswego are located in the same block of trees, grafted to the same rootstock, with very similar trunk diameters. In 2017, our Greenrivers were loaded with nuts. In contrast, Oswego trees had a good crop of nuts but the limbs weren't hanging on the ground like our Greenriver trees.
Over-production reduces kernel quality. With Greenriver, over-production caused a darkening of the kernel and meats that were not solid. Over-production is a manifestation of Greenriver's strong tendency towards alternate bearing. Next year, our energy-drained Greenriver trees won't have the capacity to produce many pistillate flowers. The 2018 Greenriver crop will be tiny. Summer shaking is the only tool we have for reducing alternate bearing and I wish we would have shook our Greenriver trees last summer.

On long cold winter days, my thoughts turn towards collecting scionwood in preparation for next Spring's grafting season. The best scions are often found growing at the tops of young pecan trees (photo at right). However, I make it a practice to wait until a tree starts bearing nuts before cutting wood from a tree. This way, I verify that the tree is true to cultivar before cutting scions.

   Walking up to the tree pictured above, I noticed that the lower branches had very short one-year-old wood and that twigs were small in diameter. Last year's wood was only three inches long (length of the blue arrow)--not nearly long enough for a proper scion stick (photo at left).
    The pedicel at the end of the shoot (red arrow) indicates that this shoot held a cluster of nuts last summer. When a branch is located within the lower portion of the canopy, the combination of partial shade and nut production slows shoot growth dramatically. With limited sunlight, the shoot invests all available energy resources into nut development rather that shoot extension growth.
    Ultimately, short shoots make poor scions because the buds on the stem are too close together and the diameter of the stem is less than that of a pencil.

High up in the canopy of the tree the shoots were longer. Normally I can find some pretty good scions at the top of a tree but in 2017 this Kanza tree had a full nut crop. Rather than growing a nice thick vegetative shoot, upper branches on this tree set a cluster of nuts (pedicel marked by purple arrow) and then produced a secondary flush of vegetative growth. The result were shoots long enough for scionwood but too small diameter to make really excellent propagation material (photo at left).

To ensure a plentiful supply of scionwood, we have developed an orchard of trees specifically trained to produce long, thick vegetative shoots. I call it training but what we are really doing is chopping back the tree to keep the tree short (so we can reach the scionwood with our hydraulic lift) and force the growth of new vigorous vegetative shoots. In the photo at right, you can see numerous shoots growing from one of our scionwood trees.

The photo at left shows a couple of one-year-old shoots that I cut out of the top of a scionwood tree. These shoots are between three and four feet in length. The buds are far apart and the wood is the perfect diameter for scionwood. When I cut scions, I'll break down these long shoots into sticks that contain at least three buds. I'll discard the terminal portion of the shoot, where buds are spaced too close together and the shoot is too thin.

One of the side effects of forcing vigorous vegetative growth on pecan trees is the development of stalked buds (photo at right). The red arrows point to stalked buds that look more like short stems than buds. Although stalked buds do not impact a scions ability to sprout and grow after grafting, I make it a practice to prune off these stalks before storing the scions in the cooler. Left on a scion, stalked buds have a tendency to puncture the plastic bags I use for scion storage. I surely don't want to risk having my scions dry out in storage because of a hole in the bag.
If you plan to graft a large number of trees, it pays to plan ahead. Develop your own scionwood trees this March and harvest high quality scions the following year. Once you finish grafting your orchard, scionwood trees can be left to grow normally and eventually return to become productive nut trees.

A few years ago, I grafted several seedling trees with scions collected from our pecan breeding project. This past fall, those young grafted trees had their first crop of nuts which gave me the opportunity to compare the nuts they produced to nuts produced by the mother tree.

When I made the grafts, I actually top-worked trees that were roughly three inches in diameter. By starting with such large stock trees, it is not surprising that these grafts set a crop in their third year. In comparison, the mother trees are 21-years-old and are 10 to 12 inches in diameter.

I was able to look at 3 clones from the breeding project. KT143 and KT149 are crosses of Pawnee and Major. KT334 is a hybrid of Pawnee and Greenriver. All three clones have been consistent producers of early ripening pecans.

It is interesting to note that all young grafts produced smaller nuts than their mother trees. I've seen this phenomenon numerous times over the years. In testing new pecan cultivars, you just don't see the full potential (warts and all) of a pecan cultivar until the tree has grown to at least 10 inches in diameter.

I also cracked a sample of nuts from each young graft and their corresponding mother tree to check for differences other than size. With KT143, the kernels from the young graft looked very different than kernels from its corresponding mother tree. Kernels from the grafted tree were shorter, almost round in shape, and darker in color. These differences in kernel appearance can be attributed to a young tree's struggle to compete with the ground cover for water and nutrients.

The KT149 kernels, like the inshell nuts, were very close in size to kernels extracted from nuts borne by the mother tree. The lower percent kernel I found from young tree nuts were probably due to kernel defects caused by stinkbug feeding. In managing my orchard, I only apply a full spray program to trees with a full harvestable crop. Since they weren't bearing enough of a crop to justify harvesting, the young KT149 trees did not receive the sprays needed to control stink bug.

When comparing kernels from young KT334 trees to kernels from the mother tree, the nut meats look identical. Surprisingly, the numbers indicate that the young trees actually produced nuts with higher percent kernel. This might be a sign that KT334 can fill kernels completely under various growing conditions or an indication that the tree never sets enough nuts to cause kernel filling problems (inherit low yields). I need to take a closer look next year.
I wanted to share these pictures from our pecan breeding work to give you some idea why it takes slow long to develop new pecan cultivars. Weighing and cracking nut samples are among the easiest measurements to record but it takes many growing seasons to learn how cultivars hold up under widely varying weather conditions. In addition, things like alternate bearing, disease resistance and susceptibility to cold injury usually aren't revealed until the trees are at least 25 years old. If I have learned anything from working with new pecan cultivars for the last 37 years it is that patience and caution are needed to avoid costly cultivar mistakes.

Today, we started cutting down trees in our block of Kanza trees to complete our orchard thinning plan (photo at right). Because Kanza is such a popular cultivar for northern pecan growers, we took advantage of having trees on the ground to cut scions from the long shoots that are usually found only at the very tops of the canopy.

After setting down the chainsaw, I walked over to the tree's canopy in search of great scionwood. Most of the shoots on the lower portion of the tree's canopy had limited one-year-old growth (photo at left). These 6 to 8 inch long shoots might be great for setting a crop of nuts but they are too small to make good scions.

The one-year-old shoots at the very top of the tree were 2 to 3 feet in length, had plenty of buds, and were 1/2 to 5/8 inch in diameter (photo at right). These shoots make great scions.

The photo at left shows you where I cut the one-year-old shoot from the tree. To the right of the clippers, note the large prominent buds on last year's wood. To the left of the clippers, the two-year-old wood has lost all its primary buds and making it a poor choice for scionwood.

We cut our scions 7 to 8 inch long and place them in a plastic container (photo at right). Before adding scions to the box, we place a bed of paper towels at the bottom of the container. Once the box is full of scions, we cover the wood with several more sheets of paper towel. Before storing the wood in a cooler, we pour cup of water over the paper towels to add moisture to the container. The paper towels above and below the scions absorb the water, then act as a wick to keep the air inside the box at 100% relative humidity. Coupled with storage at 36 degrees F, the plastic boxes and wet paper towels will keep the scion fresh until grafting time.

Pecan germination in the shuck

That one pecan that doesn't open

Our latest pecan cultivars have split shuck

The visual benefits of pecan disease control

The 2017 harvest begins

Who's eating my pecans?

A mild freeze and pecan leaf fall

Harvesting Pawnee pecans

The cost of scab infection

Same seed source--big differences in rootstock growth

Pecan shelling quaility: Genetic links

Site selection and pecan production

Stuart in the north

Native pecan yield 2017

Yields from a young pecan orchard

Deep winter chill

Greenriver vs. Oswego: Kernel quality problems

Selecting scionwood

Evaluating pecan cultivars takes time

Thinning trees and cutting scionwood