Nut expansion begins for early ripening pecan cultivars

    Earlier this week I collected some nut samples from 3 pecan cultivars. The first tree I visited was a Henning, one of the earliest ripening pecan cultivars we have in our collection. I then cut nut clusters from a mid-season ripening Kanza tree and a late-ripening Maramec tree. At this point in the growing season, you can see that Hennnig nuts have already started to plump-up and have entered the phase of rapid fruit expansion (photo above). Kanza and Maramec still looked to still be in the post-fertilization phase; just waiting around to start fruit expansion.

Cross sections of a Henning, Kanza, and Maramec nuts (left to right)

    Cutting into the nuts confirmed my suspicions about the stage of nut development for each of these cultivars (photo at left). The cotyledon of the Henning nut has expanded into a large heart shape; the first indicator that the nut has started into rapid fruit expansion. In contrast, the Kanza and Maramec nuts had small oval-shaped cotyledons. Rapid fruit growth for these  two later-ripening cultivars has not yet begun. 

Fall webworm colonies becoming obvious

    Driving along the highway, I've started to notice numerous colonies of the Fall Webworm. Webworms create a white web around their colony of 30 to 100 caterpillars (photo at right). The web serves as protection against both predators and parasites. Each evening the caterpillars work to extend the web further out into the canopy to capture fresh green leaves to feed on. The webs we are seeing now represent the first summer generation of the fall webworm. A second generation will appear in late August to early September.

   If you look closely inside the web, you will see an army of yellow to rust-orange caterpillars feeding of pecan leaves (photo at left). At maturity these caterpillars will grow to 1.5 inches long and be covered with long white hairs. Eventually, larvae leave their protective web and drop to the ground. The caterpillars will then crawl into ground-cover litter and pupate. A white moth will emerge from the pupal case and fly up into the trees to initiate a second summer generation.
   Many folks believe that they need to penetrate the web with an insecticidal spray to control this pest. Since the caterpillars are continuously expanding their web in a quest for more green leaves, applying an insecticide on the foliage surrounding the web will effectively control this pest.
    In commercial pecan groves, there should be more than 5 colonies per acre to justify an orchard wide insecticide treatment. This spring, I have seen very few webworm colonies in pecan groves that were sprayed for pecan nut casebearer. It seems that the residual action of the earlier applied insecticide treatment has kept early-hatch webworms in check.

hoo... hoo..... is sitting on my bird perch

     Every year when I give grafting schools, I stress the need to attach a "bird perch" on the tree to protect the scion from birds landing-on and breaking-over the newly attached graft. Common song birds that like to perch on new grafts include; red-winged black birds, meadowlarks, and sparrows, bluebirds and starlings.  I never expected that an owl would perch on one of my trees.
    About a month ago, my neighbor stopped to tell me he had seen an owl perched on the bamboo stake I had attached to a tree I had top-worked. He was amazed that my bird perch was strong enough to hold such a large bird.  I knew a pair of Barred owls were nesting on my farm because I had recognized their distinctive call (sounds like--"Who cooks for you, who cooks for you all") earlier this spring. Even though I heard them calling, I never got a good look at them until this week.
    The other evening, I was finally able to photograph one of our resident Barred Owls. The owl was perched on a steel fence post that holds one of my tree cages in place around a seedling pecan tree (photo above). From the owl's perspective, this was the perfect spot to hunt for mice and voles that live in the turf between my young trees. Barred owls can grow to 25 inches tall with a wing span of 3.5 feet. Barred owls will also dine on squirrels, so I hope this pair of owls stays around for many years to come.

How pecan branches can tell a story

   I was in the orchard looking at our nut crop when I spotted a group of limbs with a story to tell (photo above).  To the causal observer, this photo may look like a simple collection of leaves, twigs and two nut clusters but let me point out several things and the entire recent history of this pecan tree comes to light.

   I'll start with last year's nut crop. The red arrow points to a dark-grey and dried up twig (photo above). This was the pedicel that held last year's nut crop. You can even see the attachment scars where the nuts were held. In time, this old pedicel will form an abscission layer at the point it connects to the main stem and will fall from the tree. However, simply finding this old pedicel tells me that this tree bore nuts in 2013.

     Once a twig produces a cluster of nuts at the terminal, vegetative growth usually stops for the year. However, weather conditions in 2013 helped to promote a second flush of vegetative growth. If you remember back to last summer, we experienced a dry early summer followed by a wet period beginning in late July. The sudden resupply of soil water encouraged two buds right below the nut cluster to break and grow. In the photo above, yellow arrows point to these second-flush shoots.

   In early April of this year, the second-flush shoots began spring bud-break just like all other one-year-old shoots on the tree. However, on April 15, cold weather froze emerging buds killing all exposed green tissues. In the photo above, the orange arrows point to frozen buds still clinging to the tree. Fortunately, pecan trees are not so easily defeated by a little cold weather. Buds lower on the second-flush shoot were fully dormant at the time of the freeze. These buds survived the cold and grew into this year's new shoots.

   In the photo above, the red arrows point to the shoots that developed after the spring freeze. Since these shoots emerged from primary buds they produced pistillate flowers and have since set nuts (in red circles).      
    In the end, a simple, close inspection of twig growth tells the recent life story of this tree. Weather conditions caused a secondary vegetative flush in 2013 but froze emerging buds in 2014. However, in spite of the weather, this pecan tree produced nuts in 2013 and 2014.