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.  

Thursday, October 4, 2012

Fall fertilization

    With showers predicted for Thursday night and Friday morning, we ran over to our local fertilizer dealer Thursday morning and picked up a load of urea. Every Fall we apply 100 lbs of urea/acre (46 lbs. N/Ac.) as part of our regular fertilizer program. Our cost for this fertilizer application was $27.15/ Ac.
   Earlier this year (March), we applied both nitrogen and potassium fertilizers to our pecan groves at a cost of $80.66/Ac. That brings our annual investment for fertilizer applications to a total of $107.81/Ac. In 2012 we applied a total of 115 lbs. N/Ac. and 60 lbs. K/Ac. Later this Fall,  I estimate that we will harvest at least 1300 lbs. pecan per acre from our native pecans. Fertilizing pecans not only increases yield, but every since we've adopted the twice a year fertilizer program, we decreased alternate bearing. 

Tuesday, October 2, 2012

Hickory shuckworm

    Today I peeled back the shuck of a Maramec pecan and found a couple of hickory shuckworm larvae (photo above). The red arrows point to the head of one larvae and the tail of another. These caterpillars feed on the shucks of pecans leaving tell-tale black tunnels in the shuck. The tunneling seems to be concentrated near the base of the nut but you can find tunnels throughout the shuck.
     Hickory shuckworm is a minor pest in our northern pecan groves. Northern pecan cultivars fill their kernels and ripen their nuts faster than the shuckworm can destroy the shuck and cause economic damage. Hickory shuckworm populations are kept relatively low in well tended pecan groves because insecticides applied in August to control stink bugs and pecan weevils also control shuckworm.

    Hickory shuckworm larvae are small white caterpillars with a red heads (photo at left). Note that these larvae are confined to the shuck and have well defined legs. Pecan weevil larvae are also white with red heads but are completely legless. Unlike shuckworm, pecan weevil larvae are usually found inside the shell of the nut. 

Monday, October 1, 2012

More cultivars split shuck by October 1st

    With many of our pecan cultivars already fully mature, I went out to search for those few cultivars that have yet to split their shucks. This morning I found three. Giles and St. Genevieve were just starting to split while Maramec was fully open. Here are this week's shuck-split photos.

St. Genevieve