Casebearer update 19 June 2013

 

    We found 1% nut entry by first summer generation pecan nut casebearer larvae this morning.
We captured 2 additional moths in all 5 of our pheromone traps. I looked at the weather forecast early this morning and discovered we would have good conditions for spraying today (low wind, temperatures below 85 and little chance of rain). Besides applying an insecticide we also made our first application of a fungicide to control pecan scab.

Catkins and pistillate flowers on a new graft

  

   I was checking the progress of new grafts the other day when I came to a Kanza scion that had not only broken bud but was producing flowers (photo at left). Flowering on a scion is not that uncommon and occurs most frequently when using scions collected from vigorous growing trees of highly productive cultivars.
   Buds on the scion were programed to produce flowers last August, long before the scion was cut from the parent tree.  Catkins production has little impact on shoot growth but pistillate flowers can slow new shoot elongation significantly.
  

   Whenever I find a pistillate flower cluster on a first year graft (photo at right), I use my fingers to pitch off the entire cluster.  With the flowers removed, the scion can get back to growing a new central leader for my tree. I should get at least 3 feet of new top growth on this bark graft this summer.

Casebearer update 16 June 2013

    Today we found the very first pecan damaged by a pecan nut casebearer larvae. If you look carefully at photo at left, you will see a small pile of insect frass near the base of the nut on the left side of the cluster. Pecan nut casebearer larvae always enter on the upper side of a nut close to the point where the nut is attached to the peduncle. When scouting for PNC damage look for the pile of frass along with some fine white webbing the insect strings between nut and peduncle.
  

     In addition, we are still catching moths in our pheromone traps (data below). Based on today's findings we are planning to spray our pecan trees for PNC and pecan scab starting on Wednesday the 18th of June.

Casebearer Update 14 June 2013

 

    We scouted our pecan trees for signs of casebearer (PNC) activity again today. As of today, we have yet to find nut entry by any first generation larvae. We are still catching male moths in pheromone traps (data above) but the numbers seem to be dropping off. Pecan nuts are just starting to show signs of enlargement indicating that the PNC egg laying period is rapidly approaching. At this point, we are preparing our sprayers to apply this year's first spray sometime next week. Monday's scouting report should help pinpoint an optimum spray date.   

Answering pruning questions

   Training young pecan trees is one of the most popular series of posts on this blog.  Many pecan growers have used my directive pruning techniques and had excellent results. But, all your pruning questions have not been answered. Recently, I've received photos from a couple of pecan growers seeking additional pruning advice. Rather than just respond to each grower individually, I've decided to share those photos on this blog so everyone can benefit from additional pruning examples.
    I received a photo of a young pecan trees with the simple question--" How should I prune this tree?" (photo above, right).
    At some point in the past, the top of this tree had been pruned off leaving a 2 inch stump and no strong central leader. Currently, this tree needs more training than actual pruning. First, I'd start by cutting off the stump at the top (cut marked in blue). Next, I'd drive a wooden or steel post next to this tree. With the stake in place, I would tie the uppermost branch to the stake, holding it in an upright position and forcing it to become my central leader (the future tree trunk).
    If you look carefully at this upper branch, you will note that side shoots are starting to develop (see area in the red oval above). Here's where you practice the 2-foot rule by removing all side shoots along the upper 2 feet of the central leader.
   The final step in training this tree is to slow the growth of the lower side shoots. I simply pinch out the growing point from each shoot using my fingers.  This should push more of the tree's growth energy into the central leader yet maintain a healthy level of foliage on the tree.
   

   The next pruning question concerned choosing a central leader. Proving that I'm not the only one that can use a computer to label things in a photo, this grower asked- "I believe the central leader should be 'A' but the other shoots marked 'B' and 'C' are out growing the assumed central leader. Should 'B' and 'C'  eliminated or pruned back?" (photo above).
    The quick answer is: 'B' and 'C' are leaves and not competing shoots. Don't prune them. The reason they are taller than the terminal of the central leader is because these leaves are older than the leaves at the terminal and thus more fully expanded. (By the way, I love the deer cage).
  

    This confusion between what is a leaf and what is a shoot gives me the opportunity to give a breif lesson in pecan botany. Pecan trees create what are known as pinnately compound leaves (photo at right). Each leaf is made up of 9 to 17 leaflets attached to a stem-like rachis. The base of the rachis is also known as the leaf's petiole. An axillary bud is found just above the connection of petiole and stem. Each fall, the tree sheds entire leaves including all leaflets and rachii.  The only thing left behind will be axillary buds and a heart shaped leaf scar below each bud.
   

    In training a young tree, you should keep your eyes on the axillary buds developing on the central leader. By early summer, stalked buds often form on a vigorously growing central leader.  The photo at right was taken this morning and a stalked bud has already formed (inside yellow oval). Allowing a stalked bud to develop into a branch creates all kinds of tree structural problems. Pinch off these stalked buds as soon as you see them. Not only will you prevent future tree branch angle problems but you will further stimulate the growth of the central leader.