A split pecan shell can be a sign of trouble inside

    Over the past week, I've been staring at thousands of pecans moving down the pecan cleaner belt. Cleaning the crop may be monotonous but it all part of the fun of pecan growing. While cleaning pecans, I always look out for anything that's unusual. I'll pull off a nut that sparks my interest and set it aside for closer inspection later. This year, I noticed several pecans that have split shells (photo at right).  There can be several causes for the shell to split open along the suture; sometimes the reason is obvious, other times you will need to open the nut to pinpoint the cause.

    The split pecan pictured above is an example of a nut that started to sprout (form a root) while still on the tree. This condition is known as Vivipary. When this nut crossed the cleaning table, I could see the dark, dried up root sticking out of the nut's apex. Using my knife, I split the nut completely open to reveal what premature nut sprouting does to kernel quality. The blackening of the kernel would make this nut completely unsaleable.

    The nut pictured above is a not-so-obvious example of vivipary. In the split, near the apex, I noticed a very small piece of dark tissue. When I split the nut wide open, I found that this nut had only just started to sprout. It is most likely that the root tissue of this nut and the root of the previous example of vivipary were killed by the extreme cold temperatures we experienced in early November (14 degrees F).

 
     Some pecan cultivars have genetically weak sutures and are to prone to splitting open as the kernel fills the inside of the shell. The pecan pictured above is an example of  a weak suture that allowed fungi to colonize kernel tissue. This is especially a problem during wet fall weather when pecans sit on the ground for weeks before they can be harvested.

   
    The final example of a split shell reveals that not all pecans with split shells turn out to have defective kernels. Now that this nut is harvested and held in a cool and dry place, I wouldn't expect the nut to become infected with kernel rotting fungi. But, if this nut was still sitting outside under a pecan tree, the split shell would make this pecan prone to picking up a kernel rot. 

The price for not controlling pecan scab

     2019 will be a year remembered in our area for its unusually frequent rain-showers. It rained all summer long and that weather pattern has continued into pecan harvest season. Only a fraction of the native pecan groves that grow along the Neosho river have been harvested. However, with much of the crop still hanging on the trees, I had the opportunity to photograft some of this year's native nuts (photo above,  right).   
    The first thing I noticed was that many of the hulls have not opened up, or if they had, opening was incomplete.
   

  Looking over the nuts on a single tree, I found entire clusters of stick-tights (photo at left). The shucks of these nuts never opened up because they were severely infected by pecan scab during our wet summer months.

   On the same tree, I could find nut clusters that had open shucks. However, even the shucks that had opened showed signs of scab infection (to a lesser extent than stick-tight nuts). To illustrate the impact of scab on native pecan yield, I collected nuts from open shucks and nuts from stick-tights.

     
    The photo above shows the nuts (top) and kernels (bottom) of the pecans I collected from open shucks as compared to stick-tights. On average the nuts peeled out of stick-tights were smaller than those pulled from open shucks. The kernels of open shucked nuts were well filled and plump. Kernels pulled from stick-tight nuts were often shriveled and dark.
   Commercial pecan growers always discard stick-tight nuts during the nut cleaning process. So in effect, scab causes total economic loss from heavily infected pecans. This year, native pecans required a strong fungicide program to prevent major crop losses. Our native trees set a heavy crop in 2019, but with the widespread outbreak of pecan scab, less than 50% of those nuts will be marketable.   

Finally, pecan harvest underway

    Last week we saw temperatures plunge into the lower teens. Then we finally experienced a string of dry weather days. These factors, combined, have allowed me to go full throttle on pecan harvest over the past several days.
     The deep cold helped to freeze dry the shucks which allows the nuts to fall freely during tree shaking (photo of Kanza nuts at right). The dry weather was needed because we've had so much rain this fall that the soil in the pecan orchard was saturated. And, you just can't pick pecans on muddy ground.

   I started harvest this year by identifying areas in the orchard that had the driest soil conditions. I use a Savage pecan shaker equipped with doughnut pads to remove the nuts from the tree (photo above).  This year, the nuts are easily removed with just a quick touch on the throttle to ramp up the shaker. I just love the sound of nuts raining down on the canopy of the tractor. It reminds me of all the great pecan harvests I've seen in the past.

   After shaking I used my pecan harvester to sweep the nuts up off the ground (photo at right). These pecan harvesters are great at picking pecans but if the soil conditions are too wet they will also pick up mud. This is why I started harvesting trees growing in the drier spots of the farm. After 4 days of drying weather, I've gotten over 80% of the farm but unfortunately it doesn't look like I'll get to those wetter spots before the next round of rainy weather sets in.
   Thankfully, I now have an ample supply of nuts picked up and safety stored in the barn. On the predicted rainy days ahead, I can begin cracking nuts to supply new crop pecans for my wife's roadside fruit market.

Hard freeze will allow full pecan shuck opening

 

    I woke up this morning and checked my thermometer. At dawn, it was 22 F (-5.5 C), cold enough to freeze both leaf and shuck tissues. By mid-morning I could see pecan leaflets dropping from my trees.  The photo at right shows a Gardner pecan tree still holding on to most of its leaves. However, the leaves have the dull green cast of freeze killed tissue.

    As I stood watching, green leaves were falling off the tree. After several camera shots, I was able to capture a flurry of leaves as they blew off the tree (photo above). Note the litter of green leaves on the ground, while a strong south wind sent several leaflets airborne.

    The hard freeze also impacted the pecan shucks. The photos above show a Kanza nut cluster before and after the 22 F freeze. A few days ago, Kanza shucks appeared to be drying very slowly. Although the shucks had split, the nut was still closely held by the 4 sections of the hull. This morning the shucks looked only slightly different. The outside surface of the shucks appeared wrinkled and the hulls were beginning to pull away from the nut. The freezing temperatures caused the cells of the shuck tissue to rupture allowing water to escape and the hull to start drying more rapidly. In a few days, a lot more of my Kanza pecans will look like the cluster pictured at right.