Wednesday, December 19, 2012

Protecting young pecan trees against deer damage

     Deer populations across the US have exploded making it increasingly difficult to grow young pecan trees. The photo at left illustrates the most common form of deer damage--buck rub.  Buck deer rub their antlers on 1 to 2 inch diameter pecan trees to remove the velvet from their antlers and mark their territory in preparation for mating season. They choose small diameter trees that are strong enough not the break under rubbing pressure but limber enough to snap back against the antlers as the animal moves his head from side to side. The result of all this rubbing is the complete removal of the bark from a large portion of the lower tree trunk. Come next spring, I will cut this tree off just below the buck rub and place a bark graft on the stump.

      After I graft a tree, I install a deer cage around the tree to protect the new graft from deer browsing (photo at right). The cage is constructed from six feet of 5-foot-tall welded wire fencing (2 inch by 4 inch grid). I use a steel fence post to hold the cage in place (tied with baler twine). In the photo, a bamboo stake is attached to the tree to provide support for the growing graft.                       I leave the deer cage around the tree until it has grown large enough to heal over the bark graft union and tall enough to emerge out of the top of the cage. During the growing season, I remove the cage at regular intervals so I can prune the tree according to the 2-foot rule. After every pruning session, I re-install the cage.  
      Once a grafted tree has grown large enough to provide me with 3 feet of  clear trunk, I remove the welded wire cage and replace it with a plastic trunk protector (photo at left). These trunk cages look like there are made out of 1 inch by 1 inch welded wire but they are actually a very stiff plastic material formed in a 6 inch diameter cylinder. The trunk guard is split along one side so you can slip the guard around the tree. I use baler twine to close the edges of the tree guard together so it forms a complete cylinder around the trunk. The primary purpose for installing these trunk guards is to prevent buck rub and so far they have done a great job. I'll leave the trunk guards in place until the tree has grown to about 5 inches in diameter. At that point, the deer seem to leave my trees alone (Although, they do like to eat any nut that hits the ground).

Friday, December 14, 2012

Testing pecan cultivars: Soil and water effects

    In testing new pecan cultivars, its important to evaluate each clone over several years and at several locations. This year provided some good examples of how location can effect cultivar performance.
    We are currently testing two early ripening clones developed by the USDA pecan breeding project at several locations. The photo at right shows nut samples of USDA 75-8-5 collected from two locations--Chetopa, KS and New Madrid, MO.  At the Chetopa site the trees are growing in a heavy clay soil without irrigation while in New Madrid the trees are growing in an irrigated sandy soil. Both locations suffered extremely hot and dry summers but you can definitely see the benefits of irrigation on nut size and shape.

   In the photo at left, you can see that USDA 75-8-9 behaved just like its sibling clone; The nuts produced under irrigation were larger and plumper that the nuts produced without irrigation water.
   Last summer, soil moisture availability had an  overwhelming impact of nut size and shape. However, during years of normal rainfall we would still see differences in nut size between these two locations. Trees growing in heavy clay soils tend to produce smaller pecans than trees of the very same cultivar grown in loamy or sandy loam soil.  But, there is one advantage of growing pecans in a heavy clay soil--Clay soils have a greater soil moisture holding capacity. During drought years, quality kernels can be produced without irrigation in a clay soil while kernels produced by trees growing on sandier, non-irrigated soils will be shriveled.   

Wednesday, December 5, 2012

Kanza: Yield and nut quality 2012

2012 Kanza Crop
    I am a fan of the Kanza pecan cultivar. These beautiful, tasty and easy-to-shell nuts are the only ones that end up in my freezer (photo at right).
    Over the past few years I've been sharing production records from a block of Kanza trees we established in 1995. Last winter we removed 7 trees from this block of 112 trees as part of a planned tree thinning operation. What is interesting is that nut production did not drop significantly from 2011 to 2012 despite the loss of 6% of the orchard's trees.
    Weather conditions during the 2011 and 2012 crop years were similar; both summers were hot and dry. In 2011 we averaged 899 lbs/acre from this young orchard, while in 2012 yield averaged 810 lbs./acre. I was really surprised that the cumulative effect of two years of  drought did not impact the 2012 crop even more that it did.

    I've been cracking Kanza nuts over the past several days and have noticed a few nuts with severe kernel defects. In the photo at left, the 5 nuts in the top row are indicative of the quality of nuts produced by Kanza this year. However, as you can see by the four nuts in the bottom row of the photo, I've also found a smattering poorly filled and dark kernels in our cracked Kanza nuts. Fortunately, the number of these wafer-like kernels is probably less that 0.1% of all cracked nuts. But this makes me wonder: Is  this year's lower Kanza yield due in part to a greater number of light nuts being blown out of the cleaner or removed from the picking table as stick-tights? I think so.

Monday, December 3, 2012

Native Yield 2012

     Lately, I've been spending a lot of time in the cab of this tractor enjoying the sound of nuts hitting the roof as I shake our native trees (photo at right). Ever since 1981, we've been collecting yield data from the same 6 one-half-acre plots of native pecans in order to provide baseline data for economic projections.
     In spite of the 2012 drought, our native plots produced the second highest yield on record. We averaged 1936 lbs./acre this year. Our highest recorded yield was 2145 lbs./acre produced in 1997. If  the summer of 2012 had provided plentiful rainfall and the larger average nut size that comes with adequate moisture, 2012 might have set a new record.
    The big crop this year was set up by the combination of 2 major weather events, both occuring in 2007. The Easter freeze of 2007 destroyed potential nut production by freezing emerging flower buds. During the fall of 2007 we harvest only 490 lbs./acre. This freeze set in motion an alternate bearing pattern that has continued since that time. We currently expect larger crops in even numbered years.
    Later, during December of 2007 we had an ice storm that ripped 50% of the branches from our trees. The removal of so much of the tree's canopy ended up reducing what should have been a big crop in 2008 by more than half.  Since that time our trees have been growing back new limbs and refilling their canopies. The 2012 season marks the first time since 2006 that our native trees have returned to their full nut producing potential. The last ten years of native pecan production from our plots is shown below.


Friday, November 30, 2012

Preparing a pecan sample for evaluation

     Each year, the Kansas Nut Growers Association evaluates nut samples, submitted by producers, for shell-out percentage and kernel quality. The results of these evaluations are exhibited at our annual meeting in March with the results published in the Kansas Nut Growers newsletter. We are currently right in the middle of pecan harvest so it is a good time to think about collecting your samples the evaluation.
    When I collect samples for evaluation I start by pulling a random sample of a singe cultivar out of a sack of cleaned nuts. The photo above shows a sample I pulled from our Kanza crop. They are all Kanza nuts but they still vary in size and shape.

     In the photo at left, I sorted through my random sample and pulled out the small, squaty, miss-shaped, or shell fractured nuts (nuts in the top row). This left me with a more uniform, and more representative sample of the Kanza nuts produced on our farm (bottom two rows).
    For evaluation purposes, we require a 30 sample. Place your sample in a paper bag that is marked with your name and the name of the cultivar. Samples should be sent to: Pecan Experiment Field, 8960 SW 90th Str., Chetopa, KS 67336. We are also interested in evaluating outstanding nuts produced by seedling trees.

Saturday, November 24, 2012

Kanza: Long term productivity

    Back in 1965 the USDA pecan breeding station set some scions of the pecan clone 55-11-11 to Kansas for advanced testing. Pictured at right is the tree grafted with that wood. In 1996, 55-11-11 was named Kanza and released as a new, scab-resistant pecan cultivar for northern pecan growers.
   One of the greatest challenges facing pecan breeders is predicting how a new cultivar will perform over the long run. And by long run, I mean 30 years and more. History is full of pecan cultivar that looked great as young trees only to fall apart in a mature orchard. Shoshoni, Chickasaw, Mohawk, and Maramec are a few examples that come to mind.
    So every year I watch this old original Kanza tree for signs of weakness. So far, this single Kanza tree has been extremely reliable, producing nuts every year with no sign of production problems. This year's crop was no different (photo above) and provides more evidence that Kanza is a cultivar for the long run.

Wednesday, November 21, 2012

Importance of a vigorous rootstock

    We were harvesting pecans today and couldn't help but notice the graft unions of two of our older trees. As I clamped the shaker onto the trunks,  I asked myself, "What happens when the scion cultivar out grows its rootstock?"
    In the photo at right, a Major scion was grafted about 4 feet up into a native pecan tree. Note the slight bulge at the graft union and the fact that the  Major top has a larger diameter than the native rootstock. This tree was originally grafted way back in the late 1950's and is currently about 2 feet in diameter. This is also the only Major tree on the research station that has out grown its rootstock.
    Major trees tend to grow more vigorously that other northern pecan cultivars. Major trees that we grafted on to Giles seedling rootstock back in 1983 are nearly the same size as the Major tree pictured here. It became obvious to me, that the Major tree in the photo, was being dwarfed by a inferior rootstock.
    I shook the tree and found its nut production to be similar to other Major trees of equal trunk size. The problem is, at 55 years old, this Major should be closer to 30 inches in diameter.  As far as I can tell, the inferior rootstock has had only one effect on the scion cultivar--it has slowed tree growth. However, slower tree growth means the tree is slower to come into bearing age and has less cumulative nut production over time.

     The Major tree is not the only tree that has shown scion over growth. In the photo at left, a Peruque scion was grafted into a native tree also sometime in the late 1950's. This tree is even smaller in diameter than the Major tree pictured above. If you take a close look at the photo of the Major tree, you can see the Peruque tree just to the left of the Major trunk in the background. Since these two trees are only 100 yards apart, it is likely that the seed parent for both inferior native rootstock trees could be the same.
     On my farm, I have hundreds of volunteer pecan seedlings that could be grafted. But which ones should I use? Will I be condemning certain scions to a life of perpetual slow growth if I choose the wrong seedling? How can I tell?
     I only graft seedlings that have demonstrated a strong growth rate--2 feet of new growth in a single year. If a tree seems to be struggling to grow as a sapling, it is a pretty sure sign that tree will not provide a vigorous enough rootstock for any scion cultivar.

Sunday, November 18, 2012

Pawnee kernel defects caused by drought

    I was cracking some Pawnee pecans and noticed that this past summer's drought didn't effect nut fill as much as it created  kernel color defects. In the photo at right the upper two kernel halves are plump and exhibit normal kernel color for Pawnee. The lower two kernel halves have dark blotches and prominent veins. Look carefully at the lower two kernels and you will see that they are also not as plump as the upper kernels. The area between the dorsal groves looks shrunken and the meats are not fully expanded all the way to the tip of the kernel.
     You can find both types of kernels produced by the same tree. Without enough available water this past summer,  the tree was unable to completely fill out the kernels of all nuts produced. 
    I've tasted both normal and darkened kernels and found little difference in flavor. However, the dark blotches can be a big "turn-off" to consumers. If  Pawnee had just produced some kernels with less than perfect kernel fill and no color changes, no one would probably notice. Blotchy kernel darkening associated with incomplete nut fill seems to be unique to this year's Pawnee crop.

Wednesday, November 14, 2012

Drought induced stick-tights

    After harvesting for a couple of weeks we have finally started to clean some of the 2012 pecan crop. Today, I walked over to the piles of rejected nuts that came out of the cleaning plant and grabbed two handfuls of stick-tights. The first handful came from the pile that was blown out of the cleaner by the air leg (photo at right). As you can see, the cleaner blew out stick-tights that had wafer-like kernels and nuts that fell out of the shuck normally but had shriveled or no kernel. These are the type of pecans we definitely want to keep out of our final product.

    I took a second sample from the the rejects that had been pulled off the inspection table by hand. These were all stick-tights but unfortunately, these nuts contained edible kernel (photo at left). The summer-long drought we experienced in 2012 has caused the shucks of some nuts not to open properly. This type of incomplete ripening seems more prevalent on trees with heavy crop loads. It's a terrible shame to waste these perfectly good kernels but if the shucks stay firmly attached the nut, the nut is  unmarketable.  Fortunately, stick-tights with good kernel inside are far fewer in number than the numerous stick-tights we are seeing being blown out of the cleaner (nuts with little or no kernel).

Friday, November 9, 2012

Incomplete shucksplit on native pecans

    Today we switched from harvesting pecan cultivars to picking some of our natives.  While shaking the trees I noticed about %5 of the trees had nuts with green shucks. I climbed out of the tractor and collected some of the green hulled pecans (photo at right). I noted that some of the nuts had split their shucks normally while others were not split at all.

     Taking my knife, I cut into the shuck of a pecan that had not opened properly and popped off the shuck (photo at left). The pecan inside was fully colored and loose in the shuck but the shuck had not split along the four suture lines. This called for futher investigation.
    I collected 3 pecans that had normal shucksplit and compared them to 3 pecans that I had to cut out of the shuck. I then cracked open each of the nuts to reveal the kernel inside (photo above, right). The 3 pecans on the right had shucks that opened normally. The pecans with shriveled kernels on the left were cut out from closed shucks.
    During a drought, some heavily bearing trees "choose" to fill only a portion of their crop. Those pecans that do not fill their kernels do not shuck-split properly. We saw the same phenomenon when we harvested our "Posey" crop.

Thursday, November 8, 2012

Bird's-eye view of pecan harvest

    A few days ago I was out in a hydraulic lift making nut counts and couldn't resist talking a photo of pecan harvest from a bird's-eye view (photo above). From 25 feet up into the canopy of our trees,  the harvester looks so small.

Tuesday, November 6, 2012

Giles ripening effected by crop load

    Thirty years ago, Giles was one of the most popular cultivars to propagate in Kansas. Selected from a native grove outside of Chetopa, Giles seemed like the perfect pecan for our growing under our conditions. But grow any cultivar long enough and you'll discover you still haven't found the perfect pecan cultivar.
    Giles has a tendency to over-produce. This leads to all the typical problems associated with alternate bearing including poor kernel quality during "on" years and next to zero crop during "off" years.  However, this year we've seen a new problem with our Giles trees--incomplete ripening.  A quick survey of Giles nuts still hanging from the tree reveals that some nuts have split shuck normally while others have not opened at all (photo above, right). At this point in the season, the nuts have have failed to split, will never open.
     I peeled out some of the "stick-tight" nuts  and cracked open the shells to see if poor kernel development was the reason for lack of proper ripening (like we saw with Posey). In every case, the kernel in the sticktight nuts were just as well filled out as nuts that ripened properly.  Something else was causing sticktights.

    Earlier this summer we recorded the amount of fruiting shoots produced by 20 of our Giles trees. These counts revealed a wide variation in crop load. We had Giles trees with as low as 16% fruiting shoots to as high as 70% fruiting shoots.  To see if crop load influenced the amount of incomplete ripening found on a Giles tree, I decided to climb into the hydraulic lift and make some nut counts.  My results can be seen in the graph above. The heavier the crop load (greater % fruiting shoots) the more incomplete ripening or stick-tights we found in the trees.
    Incomplete ripening due to fruiting stress may occur in other cultivars but it is most pronounced with Giles. The drought we experienced this past summer may have also contributed to making the problem worse in 2012.

Wednesday, October 31, 2012

Kanza - Quality kernels at any size

    I admit, I am a fan of the Kanza pecan cultivar. One of the reasons I'm such a fan is that Kanza seems to produce quality kernels even under the most severe growing conditions.
   All the nuts in photo at right are all collected from Kanza trees this year. On the left side of the photo are nuts and kernels collected from trees growing in the Neosho River flood plain (Osage silty clay soil).  On the right side are smaller Kanza nuts produced by trees grown on a "second bottom" or Cherokee silt loam soil.  Previously, I wrote how soil type and position in the landscape influenced water stress intensity this past summer. In this case, a serious lack of water for trees growing on the second bottom site led to a dramatic reduction in nut size. However, the nice thing about Kanza is that regardless of nut size, kernels are always bright and plump.

Tuesday, October 30, 2012

Productive and scab free: Kanza, Lakota and Oswego

Kanza nuts ready to shake
    Testing pecan cultivars has always been a big part of the my work. Choice of cultivar is critical for the long term success of a pecan planting. In recent years, I've emphasized the importance of grafting scab resisitant pecan cultivars to help reduce management costs. Three scab-free cultivars that have done exceptionally well at our location are Kanza, Lakota, and Oswego.

Kanza crop load


   With most of the leaves now fallen from the trees, I was able to get a good look at the nut crops produced by these three cultivars this year. While not limb breaking, Kanza, Lakota, and Oswego all held good crop loads (photos at left and below).  Nut size for the three cultivars was below normal (because of the 2012 drought) but all nuts showed good kernel fill.

Lakota crop load

Oswego crop load

Monday, October 29, 2012

Harvesting intercrop soybeans

   Today we took a break from pecan harvest to cut our soybean crop (photo above). The beans were planted within a block of pecan trees that were established in 2002 using a double row planting plan. We planted the beans back in early June and they fought their way through this past summer's heat and drought.  Amazingly our bean crop ended up yielding 27 bu./planted acre. This year we will also harvest a small pecan crop from the trees in this block adding to the total income/acre.

Saturday, October 27, 2012

Pecan identification: Greenriver vs. Oswego

Greenriver (left) vs. Oswego (right)
    Over the last few years, I've told you about a new scab resistant pecan cultivar that we have named Oswego.  Oswego is a  seedling of the Greenriver cultivar and if you compare the two nuts they look almost identical (photo at right). Place the nuts side by side and you'll find a similar nut shape, similar shell markings (lots of black speckles with a few black stripes), and each nut has a raised ridge along the suture of the shell. So how can I tell Oswego nuts from Greenriver nuts?  I look at each nut from the bottom.

    By turning each pecan and looking at the base of the nut you can see the shape of the nut in cross-section (photo at left). Note than the Greenriver nut is oval in cross-section while Oswego is nearly round.
    Pawnee and Gardner are two more cultivars that also look identical to each other. Nut size and shape are the same. Both cultivars even ripen at the same time. However, when you look at each nut in cross-section a cultivar difference becomes apparent. Pawnee has a oval shape in cross-section while Gardner is rounded.

Wednesday, October 24, 2012

Drought induced kernel defects

   I was out in the grove checking trees to determine which cultivar we were going to harvest next. As I walked under a Pawnee tree, I grabbed a few nuts and cracked them to check their kernel quality. Among the nuts I sampled, I found two that displayed common drought induced kernel defects (photo at left).
    The nut kernel at the top of the photo is covered in a fine light tan fuzz. Kernel fuzz is not a disease but simply a portion of the internal shell packing material that adheres to the surface of the kernel. Fuzzy kernels occur when insufficient soil water (i.e. drought) retards kernel expansion, preventing the kernel from tightly packing internal shell materials against the inside of the shell. Kernel fuzz is easily scraped of the kernel and does not represent a health risk if eaten.
    Another kernel defect, directly related to a shortage of water during the kernel filling process, is a shortened kernel half (nut at the bottom of the photo).  In this case, one side of the kernel didn't grow out to the end of the nutshell  because there wasn't enough water available to plump out both halves of the kernel. Short kernel halves have no impact of kernel eating quality but their occurrence reduces the total percent kernel harvested from a tree.

Tuesday, October 23, 2012

Early harvest

Shaking 'Posey'
Harvesting 'Posey'
     One of the advantages of having pecan cultivars ripen 18 days earlier than normal is that we were able to start harvest earlier than normal (photo above and at right).  Today, we started on some 'Posey' pecan trees. The nuts shook out well but we noticed some green hulled nuts dropping along with nuts that fell fully free from the husks.
    Because of the high moisture content of the green shucks, we decided to run our harvested nuts immediately through the cleaner to blow out any loose green shucks and to remove nuts with the hull still firmly attached. Green shucks in a sack of pecans can cause terrible mold problems.

"Stick-tights" collected during harvest
    Posey had shuck split way back on September 18th; so why where some nuts not opening more than a month later? I collected some of those green hulled nuts and cut them open to check on nut development.  In every case, I found a paper thin kernel (photo at left). One way pecan cultivars deal with drought is to abort a portion of their crop when the nuts are in the water stage and before the tree makes any carbohydrate investments in kernel deposition. These nuts, with little or no kernel development, end up becoming "stick-tights" and are discarded during the cleaning process. 

Friday, October 19, 2012

Common tree training mistakes

    A couple of weeks ago, I visited an orchard of young pecan trees growing in SE Missouri. The owner was obviously proud of his trees and was excited by smattering of nuts produced by the trees. However excited he was by the performance of his trees, I was even more thrilled to find a single location to photograph all the common mistakes growers make in training young trees.  
    I've talked at length about training young trees in previous posts. Almost all of the mistakes growers make in training young trees are related to a lack of appreciation for a pecan tree's natural growth patterns. Lets look at some examples.

     In training a young tree, developing a strong central trunk and wide angled lateral branches is critical for supporting a heavy crop of nuts. Here's a tree with no obvious central leader and several narrow angled branches (photo at right). The branch pattern seen in the photo developed a long time ago--all the way back to when this tree was a recently planted nursery tree. As growth began that very first spring, 3 to 5 buds near the terminal of the tree broke all at once and started growing. From the looks of the branch structure, even some secondary buds broke at the same time. This common bud break pattern is the reason summer pruning is so important for developing a central leader tree. Pruning the terminal of a young tree to a single growing shoot shortly after bud break is critical for defining and keeping a dominate central leader.

     Allowing a tree to develop two major leaders is another common mistake (photo at left). The narrow angled crotch between the two forks of the tree is inherently weak and subject to breakage. Sure, correcting this problem is easy--just use a chainsaw to remove one on the two leaders. However, waiting to correct this problem until this point in a tree's life will result in removing one half of the canopy and 1/2 of next year's nut crop.
    The photo at right is an example of what happens when a tree gets over-pruned. Growers are often in a hurry to 'push' a tree taller--it makes it easier to mow around. But pruning too much can cause the tree to grow in unexpected ways. In this case, the sudden exposure of the trunk to full sun has caused epicormic sprouting along the lower portion of the trunk.  If trunk sprouts had not developed on this tree, the southwest side of the trunk may have become scalded by the summer sun. Sun scald has the potential to kill the trunk's cambium on the exposed side of the tree and slow trunk diameter growth. 
     Lower limbs need to be removed slowly, over time. My rule of thumb is to never remove more than two lower limbs per year.
    For detailed instructions for training young trees including "directive pruning" and the "two foot rule" read through my blog series starting here.

Wednesday, October 17, 2012

Mouse ear and container grown pecan trees

Container grown pecan tree displaying "mouse ear" symptoms
     I like to transplant pecan trees in the fall. Fall planting allows the tree to develop new roots in the soil long before a new flush of leaves starts to develop the following spring. We use container grown trees for fall planting but it turns out that growing pecan trees in a soil-less potting media is not as easy as you might think. One of the most common problems associated with container growing of pecan trees is a nutrient deficiency called "mouse ear" (photo above).

Mouse ear leaf vs. normal pecan leaf
    Mouse ear symptoms include smaller that normal leaves and leaflets that have a more rounded appearance. The photo above illustrates the differences between a leaf displaying mouse ear (left) and a normal pecan leaf (right). 
    Mouse ear is a nutritional disorder caused by a lack of the micronutrient, nickel. Nickel is an important component of an enzyme used by pecan trees to transport of nitrogen from the roots to leaves. Nickel deficiency can be prevented by adding a nickel containing fertilizer to the potting media before planting or by making foliar applications of nickel during the growing season.  A product called Nickel plus has been developed for use on pecan trees. 

Tuesday, October 16, 2012

Fall Gold

     Pecan leaves are turning golden yellow and pecan harvest is just around the corner. This is such a great time of year to be out in the pecan grove.

Monday, October 15, 2012

Young trees suffer from Bermuda grass competition

Bermuda grass competes with young tree
     Bermuda grass is probably the most competitive ground cover commonly found in young pecan orchards. Try as you may to develop a weed free zone around young pecan trees; Bermuda grass will creep back, covering every inch of available soil. In the photo above, you can almost see where this pecan grower had sprayed glyphosate herbicide in a ring around his young tree. By early October, Bermuda had recovered the ground.

Light green leaves indicates low nitrogen
    Although all species of grasses are competitive with young trees, Bermuda is one of the toughest competitors for three reasons. Bermuda is a warm season perennial grass that actively competes with the tree for valuable summer soil moisture. Bermuda is also very aggressive in extracting nitrogen from the soil. In fact, the leaves on trees in this planting were light green indicating low leaf nitrogen levels (photo above).
    The third reason Bermuda grass is so competitive with trees is that it secretes allelopathic chemicals from its roots which suppresses the growth of other plants including pecan trees.  Once Bermuda grass is established in a pecan orchard it it very difficult to control. Only orchard wide and repeated applications of gylphosate seems to do the trick.
    I a twist of nature's irony, pecan trees will eventually win the war against Bermuda grass. Given enough time, pecan trees will grow so large as to completely shade out the low-light intolerant Bermuda grass.  

Thursday, October 11, 2012

Site selection, water, and pecan performance

    This morning I cut nut clusters from two trees (photo above). Both clusters were cut from 'Faith' pecan trees, and both were taken from trees that have grown to about 5 inches in trunk diameter. The cluster on the left has been shuck split for quite some time and the nuts have decent size. In contrast, the cluster on the right is only now starting to split open and the nuts are tiny, about the size of a small native pecan. What caused this difference in tree performance? Location, location, location.
    The cluster on the left was collected from a tree growing in the Neosho River flood plain growing in Osage silty clay soil. The cluster on the right was collected from a tree growing in Cherokee silt loam soil which is a "second bottom" soil found adjacent to the Neosho River flood plain.
    Small nut size and a delay in maturity is caused by an extreme shortage of water.  Both Osage and Cherokee soils are deep, heavy, and poorly drained. Although Cherokee silt loam has a somewhat lighter texture than Osage silty clay and primary difference between these two soil types in terms of pecan performance in 2012 was position in the landscape. When the Neosho River runs over its banks Osage soils are flooded. Cherokee soils haven't been under water since the melting of the glaciers at the end of the last ice age.
    This past spring we had a flood on the Neosho River which covered all the pecan groves growing in Osage soil. That flood recharged the subsoil moisture lost during the 2011 drought and provided valuable moisture for the 2012 crop. The tree growing in the upland position (Cherokee soil) was not flooded and did not receive enough rainfall during the season to recharge the soil's moisture reserves. As a consequence the tree growing on the upland suffered greatly during our second dry summer in a row.
   When it comes to pecan tree performance,  the importance of good site selection can never be over-emphasized.

Wednesday, October 10, 2012

Shuck split still 18 days early

    Over the last 5 weeks I've been posting photos of pecan cultivars as they split shuck (Sept. 4, Sept. 11, Sept 18, Sept. 25, and Oct. 1). Today, I found that the latest ripening cultivars we have under test had split their shucks. That's roughly 18 days earlier than normal.
   Caddo, Oconee, and Stuart are not recommended for planting in Kansas because they often do not ripen their pecans before our first fall freeze. However, this year all three have split their shucks well before our average date of first fall freeze (Oct. 20).


Monday, October 8, 2012

Pecan cultivar testing takes time

Kanza pecans
     One of the most common questions I receive is: "Are there any good new pecan cultivars I need to graft?".  The fact is that pecan cultivar development and testing is a slow process. 'Kanza', today's most popular northern pecan cultivar, was created in 1955 when the USDA's pecan breeder, Louis Romberg, applied 'Major' pollen on a 'Shoshoni' pistillate flower. It wasn't until 41 years later that 'Kanza' was named and released for propagation in 1996.
     Originally, 'Kanza' nuts were regarded as too small and not the proper shape for a commercial pecan cultivar. Pecan scientists across the south began removing 'Kanza' from their cultivar trials. A single tree was grafted to Kanza at Pecan Experiment Field in 1964 and that tree now stands proudly as the oldest Kanza tree in the country. The moral of this story is, that sometimes, its takes decades to see the true value of a new pecan cultivar.

City Park
    That brings me back to potentially new pecan cultivars. This fall I collected some nuts from the pecan clone we have called 'City Park' (photo at right). The nuts on the left in the photo were collected from a tree planted in 2002 and roughly 4 inches in diameter. If I were to judge this clone by this nut sample alone, I would probably discount 'City Park' as no better that a good native pecan. The nuts on the right in the photo were collected from the original tree that I planted back in 1982. The larger tree, with a more extensive root system, was able to capture more water from the soil in this dry year and produce larger nuts. These larger nuts are more impressive and are the reason we have moved 'City Park' into advanced testing.

    During a dry summer, nut size will be related to tree size. The photo at left shows Kanza nuts collected from two different size trees. Again the samller tree produced smaller nuts (not by much). The question becomes: "How big does a pecan tree need to grow before we start seeing a cultivar's full potential in terms of nut size?".  From my experience and the photographic evidence shown here, I'd say a pecan tree doesn't reach it full potential until it grows to over 10 inches in trunk diameter.
    One of the reasons it takes so long to develop and test new cultivars is because it takes 18-20 years to grow a pecan tree to 10 inches in diameter. However, waiting until a clone reaches it full potential is the only way to be certain a cultivar will perform in the long run.