Tree spacing influences nut production during drought

 

    The other day I was scouting my orchard for pecan shuck split when I noticed a dramatic difference in nut size and ripening between a young grafted Caney tree and the mature mother Caney tree located in my pecan breeding block.

    Let's look at the trees in question. The photo at right is a young Caney tree. This tree has a good crop of nuts and the nuts are only slightly smaller than normal. The important thing to notice in this photo is how much open space there is around the tree. In a year of short water supply this Caney tree has very little competition from other trees for water.

    The photo at left shows the original Caney tree growing in my pecan breeding block. This tree is much larger (28 yrs. old) and is crowded by other large trees (note the shade on the ground). Note the yellowing of some of this tree's leaves. This is an indication of extreme water stress caused by the competition for water from neighboring large trees. Although there is a good crop of nuts on the tree, the nuts are tiny.

  

     The photo above illustrates the differences I observed in the nuts produced by the young, well-spaced Caney tree and the mature, crowded Caney tree.  First there is the obvious size difference. But secondly, note that the nuts produced by the young tree have split shuck while shucks are still firmly attached over the nuts collected from the mature tree. This simple observation leads me to a very important decision; After harvest, I need thin out more trees in the pecan breeding block.

      Caney is one of the scab-resistant cultivars I developed from my pecan breeding project. The photo above gives you a good idea of what Caney nuts look like. Over the years, Caney has produced nuts that are larger than Kanza with nearly 53% kernel. Caney matures a week before Kanza. This cultivar has a protandrous flowering habit making it a good pollen pairing for Kanza. Kernels are straw-colored and  have excellent quality.

Severe drought impacts pecan production

    For the past 4 months, I have watched clouds pass over SE Kansas without dropping significant rainfall. According to the National Weather Service, my farm in Cherokee County (extreme SE corner of Kansas) is experiencing an Exceptional Drought (figure above). I've lived through several Kansas droughts but this year is most memorable because of its extended duration. Extreme drought, although uncommon in SE Kansas has occurred several times in the past 100 years. The Dust Bowl of the 1930's is probably the most historically significant drought to impact Kansas agriculture. However, other exceptionally dry periods occurred  during the 1950's and as recent as 2012-2013.

   The dry weather has definitely illustrated why pecan trees prefer growing in the deep soils found in river flood plains. These soils have a large sub-surface reservoir of water that can move up through the soil profile to keep pecan trees green and growing. However, this year's limited water supply has impacted the 2022 nut crop. Nut size and kernel fill will both be reduced. Many trees aborted a portion of their nut crop in mid-summer due to drought. I have also noted that shuck-split is delayed compared to normal years. 

    Now that the days are getting shorter, I should have more time to post on this blog. As you might expect, the drought of 2022 will color my observations for the remainder of this crop year.