2011 Native pecan yields

   For over 30 years, we have harvested native pecans from 6 one-half acre plots in an effort to create a historical record of nut production from well managed trees.  After cleaning pecans for nearly 2 weeks straight, the yield data from these native plots has been recorded. The plots averaged 1294 lbs./acre in 2011. The lowest yielding plot produced at the rate of 866 lbs./ac while the highest yielding plot made 1910 lbs./ac. These same plots averaged 1286 lbs./ac last year (2010).

    Here's a chart of yields from our native plots over the last 10 years. As noted on the graph, the 2007 crop was limited by the Easter Freeze which destroyed most emerging new shoots and the pistillate flowers contained in those shoots. The 2008 crop was limited by the December 2007 ice storm that broke nearly 50% of the limbs off our native trees. After 2 years of strong vegetative growth (2008 and 2009), our native trees have begun to bear at pre-2007 levels. It will be interesting to see how our trees react next year, following the stress of the 2011 drought.

Pecan harvest patterns

    The pull-type picker has become the mainstay of the native pecan industry (photo at right). The other day, I drove past two native pecan groves and noticed huge differences in the pattern of leaves left on the ground after being blown out the back of the harvester.

    In the first grove, you can see a distinctive circle of brushed grass around each tree with all the tree leaves scattered around the outside of the circle (photo at right). This grower picked each tree individually, starting at the dripline of a tree and working towards the trunk in a circular path.

    In the second grove, the leaves were left in long rows, indicating the the harvesters were driven in a straight line, weaving around trees as they harvested large blocks of trees at a time (photo at right). In this case, the grove was picked much like you would mow the orchard floor. You start on the outside of the grove and work your way towards the middle of the field.
    There is not a right or wrong way to harvest nuts. Both of these harvest patterns seem to work. However, at the Experiment Field, we tend to harvest our native trees in blocks rather than individual trees. Driving around in circles tends to make the operator crazy and I feel like the harvester can capture a wider swath of ground by driving a straighter path.
   These photos also illustrate one very important difference between these two groves. Note the amount of leaves left behind after harvesting.  The grove harvested in circles had far fewer leaves on the ground than the grove harvested as a block (the grove with more leaves). These two groves are adjacent to each other but only the second grove receives annual applications of nitrogen fertilizer.  Regular nitrogen fertilization stimulates the growth of more leaves, more leaves capture more solar energy, and more energy in the tree results in more nuts.
     Before harvest you could see an obvious difference in nut production between these two groves. After harvest the leaves tell the same story.

Stratifying pecan seeds

    If you have even considered growing pecan trees from seed, the nuts will need to go through a process called stratification before they will germinate properly. Stratification is a simple process that involves soaking dry seed in water then storing that wet seed in a cool moist condition for 90 to 120 days. With stratification we are basically mimicking what happens in nature. A squirrel buries a pecan in the soil during the fall where it remains cool and moist all winter long. The squirrel-planted seed doesn't germinate until the following spring when the danger of frost has past.

   Here's how I stratify pecans for next year's planting.  First, I place new-crop nuts in a plastic container, filling it about 1/2 way. I then fill the box with enough water to cover the seeds and let the seeds soak overnight (photo at right). You will need to stir the nuts around in the water  once in a while so the nuts on top don't dry.

   After soaking. I add a moisture holding media to the nuts and water. In the past I've used peat moss, cedar shavings, potting soil or saw dust. This year I had plenty of saw dust on hand, so I mixed the dry saw dust into the nut and water mix (photo at right).  I used enough sawdust to surround the nuts and soak up much of the free water. I let the saw dust soak up the moisture for a few hours then pored off any excess free water out of the box. I then placed the tight-fitting lid on the box and placed the box in the refrigerator.
    For the stratification process to work effectively, the nuts should be held in cold storage at between 32 and 40 F (typical refrigerator temps). For northern pecan cultivars, germination is more uniform when nuts are held a full 120 days in stratification. By stratifying nuts now, you will have nuts ready for planting by May 1st, a perfect time for planting pecan seeds.

Crows are a major pecan pest

A couple of crows high in pecan trees

    Every year crows from all over the upper great plains migrate south for the winter in search for easily-accessible, high-energy food sources. Unfortunately, that means they like to stop in our pecan grove right at harvest time to feast on pecans. Its hard to photograph crows (photo at right) because they are such wary birds. Or, maybe, they have come to realize that a man on foot in a pecan grove is often followed by shotgun blasts.
    It is estimated that a single crow can consume 15 pounds of pecans per month. Crows will knock nuts to the ground, hold the pecan between their feet, and crack open the shell with their large, heavy beak. After cracking the nut open, they pick out the kernel, leaving shell and packing material on the ground.

Pecan shells left after crow feeding

   If you walk out under your trees you can spot the shell fragments left by crows (photo at left). You usually don't see a lot of shells in one location but I gathered up a few examples and placed them all in one photo.
    Crows have become an increasing problem for pecan growers ever since they became federally protected bird--a result of the NAFTA treaty (the crow is the national bird of Mexico). Later this winter, we will be holding a meeting with Federal and State wildlife managers to develop an action plan for reducing crow populations. Watch this blog for further details as we make plans for this meeting.

Watch for old pecans gathered at harvest

    Here's a photo of three pecans we picked up with the harvester this fall. You might recognize these nuts as being all from the same cultivar--Kanza. The light colored nut on the right is from this year's crop, while the other 2 nuts were left behind from the 2010 crop. One of the things we look to remove from the cleaning table are old nuts that usually appear as dark reddish black nuts (nut pictured in the center).  After sitting on the ground an entire year, these nuts become rancid and/or moldy.
    We missed the moldy nut on the far left on the cleaning table only to find it later in a batch of cracked nuts. Look at the shell that still remains on the moldy nut. Its darker than the new crop nut but doesn't have that oil soaked appearance of the nut pictured in the middle. With thousands of nuts moving across the cleaning table, it easy to see how we missed pulling the moldy nut (before it was cracked) out of our 2011 crop.
    I find it remarkable that pecans missed at harvest can survive an entire year out in the field without being discovered by squirrels, mice, crows, woodpeckers, insects and even deer. However, every year we find just a few old nuts come racing across the cleaning table that need to be thrown in trash pile.

Pecan harvest 2011

Sonja raking sticks off the orchard floor

    We have working hard to harvest this year's pecan crop before the rain and snow of winter rolls in. Since I usually end up shaking our native groves, I get a pretty good idea about the size of our crop by the sound of nuts hitting the top of the tractor cab. This year's crop will be slightly smaller than last year's harvest mostly because  the 2011 drought decreased average nut size.
    While shaking our trees, I started  thinking about area farmers that have spent most of harvest season complaining about a lack of nuts in their groves.  One guy even argued that the cold temperatures we had last February (-17 F) were the reason he didn't have a crop. But when confronted by the fact that the Experiment Field was producing nuts in 2011, he simply stated that a dome of warm temperatures protected the trees just east of Chetopa. Talk about hot air!

Darrell harvesting pecans

    The real reason growers don't see annual crops in their groves is because they cut corners when it comes to annual inputs. If you want consistent nut production, fertilizing the grove twice a year every year is a must. In 2011, we spent $90.58/acre on fertilizer. We applied 70 lbs. N and 60 lbs. K in early March and 46 lbs. N in October. Our native pecans will yield around 1000 lbs/acre; more than enough to cover the cost of ferilizer.
    Pesticides are another major input for pecan producers. This year we invested $42.63/acre in insecticides and fungicides. We sprayed for casebearer and scab in June, stinkbug and weevil in August, and weevil in September. This year's dry summer helped prevent the spread of pecan scab.  As a result, our fungicide applications were kept to a bare minimum and we were able to save a little money.

Cracked pecans

    It takes several years for pecan trees to respond (bear nuts) to fertilizer and pest control. It takes even longer to build up tree strength with years of consistent inputs to achieve reliable annual nut production. 
    

Fewer black spots on kernels in 2011.

    Its not until you crack open a sample of  this year's pecan crop do you discover the level of damage created by stink bug feeding. As I mentioned in an earlier post, the black spots found on pecan kernels are the result of feeding by stinkbugs and/or leaf-footed bugs (photo at right).
    Last year (2010) we found quite a bit of stink bug damage. This year (2011) the number of kernels with black spots are far fewer. I wish I could come up with a good explanation for the year-to-year variation in stink bug damage but it turns out that the movements and population numbers for this group of plant feeding bugs are very hard to predict.
    Over the past several years, our  control strategy for kernel feeding bugs has been to apply an insecticide (Warrior II) in early August. Subsequent insecticide applications aimed at pecan weevil also help decrease stink bug populations. These control measures are not perfect but seem to keep kernel damage down to less that 1% of kernels.

Ice storm recovery update

    Its been 4 years since the pecan groves around Chetopa,Kansas were hit by a massive ice storm. Once the leaves have fallen from the trees you can still see the scars of limb breakage left behind in the canopies of our trees. In the photo at right, you can see that vigorous new shoots have developed where limbs were torn from the tree by the weight of the ice. With each passing year, our trees are filling out their canopies, increasing the area where nuts can be produced.

    But where are the nuts? It seems that the native pecan trees that did not set nuts on undamaged limbs, didn't set a crop on the new shoots either. In contrast, native trees that did set a crop (photo at left) produced pecans on both old and new branches.  What we are seeing at this point is that the new shoots developed in response to ice-induced limb loss are now fully mature (able to produce a nut crop) and synchronized with the entire tree.

    If you take a closer look at the regrowth associated with ice-storm-related limb breakage, you can see that an over-abundance of new shoots have developed in many areas (photo at right).  Note that these vigorous branches have also developed numerous lateral shoots. As the trees continue to grow, competition for sunlight among these new shoots will eventually lead to the  natural thinning of the most heavily shaded limbs (the so called self pruning process).

   Squirrel damage has also led to some much needed limb thinning on ice-damaged trees. I've been shaking trees this harvest season only to find several branches that have developed since the ice storm on the ground (photo left). Note the dried leaves still attached to the shoot indicating that this shoot was injured by squirrels last summer.

    If you look at the base of the shoot you can clearly see that the bark had been stripped back by squirrels feeding on the cambial layer of the shoot. A combination of summer winds and harvest tree shaking snapped these dead shoots out of the tree.