Young tree's growth response to spring time directive pruning

    In previous posts, I've stressed the importance of practicing directive pruning during the spring flush of growth to encourage the development of a strong central leader. The photos at right show the pruning cuts I took back in late May of this year. At first glance, it looks like I'm trying to create a single-stemmed tree with no side shoots.

However, that is not the case at all. These early-season pruning cuts are designed with the single focus of promoting a single central leader. New lateral branches will develop, but later in the season and at much more desirable branch angles. 

 

  In mid June, I returned to the tree that I pruned in May. In the photo at left you can see that I have successfully maintained a single central leader. But you should also notice that there are now numerous lateral shoots sprouting out from the trunk all below the new central leader.

     On closer inspection (photo at right), you will note that the new lateral shoots are growing from secondary buds that are located just below each pruning wound (the pruning cuts I made in May). It is also important to note that these new shoots are growing out at a wide angle from the trunk. These shoots will develop into strong well-anchored branches that resist wind and ice breakage.

    By early July, all of the new lateral limbs are growing nicely (photo at left). It won't be long before I have well bushed out tree all while keeping a single central leader. I'll leave all these lateral branches on the young tree to help promote trunk diameter growth. The increased leaf area on the trunk catches more wind which, in turn, promotes a strengthening and thickening of the trunk. 

    Young, rapidly-growing trees need training throughout the summer months. Pruning cuts made to strengthen the dominance of the central leader usually means that stalked buds will start to form in mid-summer on the central leader near the top of the tree. Left to grow, stalked buds will produce narrow-angled branches that develop a bark inclusion at their base. If all the stalked buds that form on a central leader are allowed to grow, a pecan tree will become top heavy and take on a broom-like appearance (at the top of the tree). I pinch off all stalked buds as soon as I see them to preserve the central leader (photo above).

   
    

Directive pruning last year's grafts

 

      Once I finish up grafting for this year, I turn my attention to pruning last year's successful grafts. The photo at right illustrates the typical appearance of a young grafted tree in its second leaf. Last year, I carefully pruned the graft to ensure a single, strong central leader. But this spring, the tree popped multiple new shoots from the terminal of last year's growth.  If allowed to remain for the rest of this summer, these multiple shoots will create what is commonly known as a crow's foot and I will have lost my central leader. That is why I'm such a strong proponent of directive pruning. By pruning during the period of active shoot grow, I can "direct" the tree's new growth into maintaining a single leader.

   The photos above shows the terminal of my young grafted tree. Three shoots have developed at the very top of the tree. I identify the strongest growing shoot among the three and then prune out the others.

     To help focus the tree's growth energy into my new central leader, I also remove all lateral branches that arise from the main stem within the top 2 feet of the tree (measuring from the top of this year's new shoot growth). (photo above)

     Since I still have the bamboo stake in place from last year, I tied the tree upright to encourage to formation of a straight tree trunk. Later this summer, I'll probably replace the bamboo with a longer (and stronger) tree stake that will help me keep this tree growing the way I want. I allow lateral branches to develop lower down on trunk (but above the graft union). Lateral branches will increase tree leaf area helping to capture more sunlight to produce the carbohydrates needed to sustain rapid tree growth. These lateral limbs also catch more wind which in turn promotes trunk diameter growth.

    The photo at right is another example of a graft in its second leaf. In the past, I've called these trees "lolly-pop" trees because of the ball of new growth at the top of the tree. This tree also needs directive pruning.

     Whenever I go to prune a young tree, I always start at the top and work my way down. In this example, I have three shoots growing at the terminal but it appears I already have a strong central shoot. However, to reinforce the dominance of this new central leader, I'll prune off all competitors. Again, I stick to the 2 foot rule--No lateral branches within the top 2 feet of the central leader.

    Once I finished pruning I noticed that I already had a couple of lateral buds breaking further down on the stem (photo at right). I make sure I leave these in place for now. 

    Many grower make the mistake of pruning all lateral branches off as soon as possible. Their thought is that by removing low limbs the tree will grow taller, faster. However this is not the case.  Removing all laterals only serves to create a tall thin tree that bends over under it own weight, often snapping in a good wind storm. Nut production will also be delayed by over-pruning lateral limbs. 

    On my trees, I leave lateral branches on the tree until the tree has developed a nice full crown. At that point, I start to remove one or two low limbs each year. My goal is to develop a tree with 8 to 10 feet of clear trunk. However, it usually takes 12 to 15 years to get to that point.
 

Directive pruning is most effective way to train young trees

     One rainy day in May, I was leafing through my pecan magazines when I came across a photo of a Georgia Extension agent discussing the pruning of a young tree (photo at right). To me, this one photo illustrates many of the worst possible approaches to young tree training. The first thing I noticed was that far too many lower limbs have been removed during previous years. Lower limbs are vital for stimulating trunk diameter growth (making a strong  trunk) and provide valuable leaf area to promote root growth. The second obvious problem was loss of a central leader and the development of a crow's foot at the top of the tree. Dormant pruning can be used to correct a crow's foot branch pattern with the selection of a single shoot to become the new central leader but when that new shoot breaks bud in the spring, a new crows foot will develop 3 feet higher in the tree. 

    I have discussed my approach to training young pecan trees is a series of blog posts published 10 years ago in this blog (Series starts HERE). Starting in mid-May and continuing through early June, I've been pruning my pecan trees using my directive pruning methods. This blog post is dedicated to illustrating the summer pruning cuts I make to direct a pecan tree's growth to ensure I create a well branched central leader tree.

  The photo at left shows the typical budbreak pattern of a young grafted tree. The graft union is painted white with the majority of new shoot growth clustered at the top of the tree. At this point, this tree would create a fabulous crow's foot if allowed to grow unchecked.

   

    My first pruning decision was to choose which new shoot would become the new central leader. Last spring's late frost killed several emerging buds (seen as brown dried-up buds in photo at right) which promoted a profusion of new shoots to grow near the top of the tree. One new shoot was growing more vigorously than all the others (yellow arrow) So I choose that one shoot to become my new leader.

    With a single pruning cut, my young tree was poised to grow a strong central leader (photo at left). However, several rapidly growing shoots just below the new leader were still in position to create unwanted competition for the leader.  

    Following my 2-foot pruning rule I pruned off any shoots on the main trunk that could possibly complete with the central leader (photo at right).  I left lateral shoots growing lower down on the trunk to help build a healthy canopy of new shoots and leaves to promote trunk diameter growth and rapid root growth. 

 

    With just a few summer pruning cuts, I directed the growth of this young tree into a more desirable tree shape (photo at left). I'll need to come back to this three in mid summer to remove any shoots developed from stalked buts and to tip back the growth of laterals.  

When summer pruning my trees I look for trees that have developed what what I like to call 'lolly-pop' tops. The photo at right is typical of this kind of growth. What you are actually seeing is the early stages of the 'crow's foot' growth pattern.

 

    Using my ladder, I climbed up to take a close look at the top of the tree (photo above). In typical fashion this tree developed multiple shoots at the tree's apex. To re-establish a central leader, I pruned off all competing shoots leaving just one to become dominate. What I'm actually doing is pruning out a crow's foot while the shoots are still growing upright and before they start spreading out laterally in all directions (to form the typical crow's foot).  

    Pruning in the summer has the advantage of removing far less wood material than what is common with dormant pruning. The green shoots I prune off can be left on the ground to be chewed up when I mow the grove.

    By pruning out the 'lolly-pop' I have recovered a single central leader (photo at left).  However, my summer pruning efforts on tree are not finished.

    On this size tree, I tip prune new lateral shoots once they have grown about 2 feet in length. This slows extension growth and encourages shoot diameter growth. When pruning lateral shoots, I always prune to an outward pointing bud (photo above). I also remove any new lateral shoots that are pointing straight upwards.

Directive pruning young pecan trees

    In between rain showers, I have been trying to work on pruning all my young pecan trees. Right now, when I look out in the orchard, I see far too many trees that look like lolly-pops; Trees with a long strait stems topped by a profusion of leaves and branches (photo at right). Left to grow unchecked, this tree would develop a terrible crow's foot and no strong central leader. To avoid future problems with tree form, I like to practice what I've termed "Directive Pruning". By selectively pruning at this time of year, I direct the tree's energy into growing a single central leader and strong lateral branches.

     This year, the mass of branches and foliage on top of my young trees seems even denser than in previous years. Just look at the top of my tree (photo at left), there are multiple shoots growing from each node. Out of this mass of foliage I'll need to select a single shoot to become my new central leader.

    The frost injury we sustained back in April is the cause for the massive profusion of shoots near the top of the tree. In the photo at right, note that there are four shoots growing from a single node. The upper bud or primary bud was killed by the frost. This prompted the secondary and tertiary buds to break and to form shoots. Even the quaternary bud has just started to develop into a shoot. By pruning at this time of year, I can direct all the tree's energy into a single shoot to become a dominant central leader. 
   

    The photo at left shows the top of the tree after I have pruned it. I kept one vigorous shoot to become the central leader. Now that all the competition has been removed around this shoot, the new growth will straighten out in just a few weeks time. I also remove all lateral branches within two feet of the tip of the central leader. This will promote the dominance of the new leader. Below that point I allow the laterals to form but remove any branches that appear to be forming a narrow crotch angle.

     With just a few snips of my pruners, I've eliminated that lolly-pop tree and created a tree with a central leader (photo at right). 

     The photo above is another example of the practice of Directive Pruning. When pruning the tree, I start at the top and select a shoot to become the central leader. Next, I remove all lateral branches within 2 feet of the apex of the central leader. Moving down the tree, I prune off any new shoots that are growing straight upwards from a lateral branch.  At this point in the tree's life, I like to keep all well-formed lateral branches in place as long as they don't interfere with basic orchard maintenance. The additional leaf area provided by low limbs promotes both new shoot and trunk diameter growth. I will remove lower limbs in time, but this tree is about 2 years away from that job.

Pruning out narrow branch forks

     This past week we had some nice weather and I spent some time in the orchard inspecting my young trees for potential tree structural problems. You could say I was on a mission to find and prune out narrow branch forks. The photo at right is a typical example.
    This tree has developed a lower limb that is growing upright and competing with the central leader. Now is the time to prune out this potential problem before I find myself with a forked tree.

    If you take a close look at the narrow branch connection (photo at left), you can see that a bark inclusion has already formed. These type of branch connections are extremely weak and have a tendency to break out during wind storms or under the weight of a heavy nut crop. To prevent future problems, I prune out narrow branch connections whenever I see them.

    Using a saw, I cut off the upright-growing, lower limb all the way back to the main trunk. When removing this branch, I made a 45 degree angle cut which should help the tree heal over the cut surface as quickly as possible (photo at right).

Summer time training young pecan trees

    Usually things dry out in Kansas come August, but not this year.  This summer has been warm, humid, and wet. And pecan trees seem to love it. All my young trees have made impressive new growth.  However, I've spotted some potential problems with the form of my trees especially at the very top of the central leader. The photo at right shows a typical young tree in my orchard.
    From this distance the tree looks in good shape. A strong central leader with some wide-angle lateral limbs near the base. But I took a closer look at the very top of the leader.

    At the very top, I found 2 shoots that have sprouted and look to to be competing for the role of central leader (photo at left).  I definitely don't  want to leave both of these shoots in place because in just a couple of years I'll be dealing with a narrow, forked tree.

   In removing one of the shoots, I choose to make the cut easiest to complete (photo above). With a single snip of the clippers, I've regained a single central leader.

     The photo at right shows another one of my trees. Again, things look pretty good but the very top of the tree is starting to look a little bushy.

    This time, lets start by looking at the lower portion of the tree's canopy (photo at left). First note that all the lateral limbs have nice wide angle crotches. Following the 2-foot rule, I tip pruned all these one-year-old side branches when they reached 2 feet in length. Note the location of the slight crook in the central leader. This is where the leader started new growth back in May. And like I've previously mentioned, my trees are growing like mad. This year's new growth on the leader has already topped five feet in length.

    Taking a closer look at one of the lateral branches, you can see why removing stalked buds is such a good idea (photo at right). Last year I cut out a shoot that had developed from a stalked bud. The stump of that shoot is still on the trunk but a  new lateral shoot has developed from a secondary bud to created a nice wide angled branch.

    Now lets focus on the very top of the central leader.
Several shoots have developed and the tree is starting to loose its strong central leader. It is interesting to note these are the first lateral limbs this tree has developed on the central leader arising from the current season's new growth. However, if I want the tree to develop lateral branches further down the stem, pruning to maintain a central leader is critical.  All that new growth on top of the tree actually inhibits bud growth further down the stem.

    Using a ladder and my clippers I pruned the top of the tree back to a central leader (photo at left).

    The photo above shows before and after pruning. The photos look almost alike except for the very top of the tree.  With just a couple of snips, I have regained an obvious single leader.

Pruning a young pecan tree back into balance

     During the cool morning hours I've been checking grafts and summer pruning young trees. Today, I came across the tree pictured at right and decided it needed to be pruned into a more balance tree shape. In general, this tree still had a well defined central leader but had one vigorous branch seemingly growing out of place. On closer investigation, I also found the top of the tree covered with stalked buds and a limb growing on the right side of the tree that had developed an over abundance of new shoots. Armed with just a pair of pruning shears, I quickly reshaped this tree.

    I started by taking a closer look at that vigorous side shoot. Tracing the limb back to where in connects to the trunk. I found the diameter of the side shoot rivaled that of the central leader (photo at left). To slow the growth of this shoot, I just need to follow the "2 foot rule" of summer pruning and limit the new growth of side shoot to 24 inches.

    When pruning back a side shoot, I always prune to a downwards pointing bud (photo at right). When this bud breaks, the new growth will be directed outwards rather that upwards to compete with the central leader.

     On the other side of the tree, I just needed to thin out some of the excess growth. Here, I pruned out all upwards growing shoots leaving only outward growing branches (photo at left).

    Next, I moved to the top of the tree. The photo at right  reveals numerous stalked buds have broken bud and have grown 6 to 8 inches in length. Left to grow, all these stalked-bud shoots would create a bushy terminal with no well defined central shoot. All this new growth at the top of the tree will make the tree top heavy and cause it to bend over from the weight (to see an example, check this post).
 

     Moving up the entire central leader, I used my clippers to remove every stalked-bud shoot (photo at left).  When I make these cuts, I make sure that I don't injury the secondary bud just below the staked bud.

 
    The photos above present a before and after look at my young Kanza tree. Summer pruning is a good way to keep pecan tree growing into a strong central leader tree.  I have found it an invaluable tool for training young trees.

Time for directive pruning young trees

    While I'm out grafting trees, I often pause at trees that I've grafted in past years to give them a little directive pruning to ensure that I maintain a central leader on rapidly growing grafts. The photo at right shows a tree that I grafted last year. I had 5 feet of new growth from the scion last summer and I developed a nice straight trunk. This year at budbreak, the very top of the tree exploded with dozens of new shoots all clustered at the very top of the tree. Left to grow unchecked, these news shoots would form a "crows foot" at the top of the tree and I would loose my central leader. A few snips with my pruning shears and I can direct all the tree's energy into growing a new central leader while at the same time encouraging lateral branching further down the stem. Let's take a look.

     My first step was to look over the very top of the tree (photo at left). I had new shoots growing every-which-way. At each bud node, the primary, secondary, and tertiary buds had broken and were developing into new shoots.

   As I looked down the stem, I passed over nearly 3 feet of dormant buds before finding a few buds breaking to form lateral branches (photo at right). This is how apical dominance works in pecan. The very top of last year's growth gets the greatest push for new growth. That growth, in turn, inhibits the growth of buds below the terminal via hormonal signals. When the hormonal signal weakens with distance this allows buds to break further away from the terminal. My goal in directive pruning is to reduce the negative effects of apical dominance on tree form and encourage both a central leader and the development of lateral branches.

    My first pruning cut was made at the very top of the tree. The terminal of this tree had at least 6 new shoots growing in tight competition. With a single cut, I began the process of isolating and developing a new central leader (photos above).

   To reduce the competition from shoots just below the new leader, I used my clippers to totally remove those shoots from the tree. (photo at left).

   By pruning the new growth at the top of the tree, I was directing all the tree's energy into my chosen central leader. However, my work was not quite done.

    I still had 3 shoots growing at the very top of the tree. With careful pruning I removed the shoots growing from the secondary and tertiary buds while leaving the shoot growing from the primary bud (photo above).

   When I finished pruning, my young tree looked sparser but I now had a single growing point at the top of the tree. And I know from past experience, that thinning out top growth stimulates the breaking of lateral buds to form the lateral shoots needed to fill out the canopy of the tree.

  I don't confine this directive pruning technique to just one-year-old grafts. The tree pictured at left was grafted 2 years ago and could also benefit from some directive pruning. To give you an idea of scale, the step ladder in the photo is four feet tall. I'll need that ladder to reach the top of the tree to make a few directive pruning cuts. 
   Note that the central leader of this tree has no lateral  branches for almost 4 feet below that little ball of spring growth at the top of the tree. Below that, the tree has developed a good framework of lateral branches. New spring growth on each lateral branch mimics what we see at the very top if the tree. New shoots are only growing from the apex of each lateral shoot.Here's how I pruned this tree.

    First, let's look the bud break from lateral shoots (photo at right). Proliferation of new shoots on the terminal of lateral shoots is a good thing. This will create an even greater leaf area for the tree to capture solar energy. However, I pay attention to the direction the new shoots are growing. I remove any new shoots that grow strongly upwards towards the central leader.

   Once I inspected the lateral shoots, I climbed up the ladder to address the new growth at the very top of the tree. Just like the tree in my last example, the very top of the tree is a jumble of new shoots with every new shoot competing for light. I pruned the top of this tree exactly like I did on the one-year-old graft discussed earlier (photos at left). 

      Pruning trees early in the season is one of the most important techniques for developing a well structured tree (photo at right). My goal is to make sure each tree in my grove develops single strong trunk. At the rate these trees are growing, it won't be too long before directive pruning the central leader will be out of my reach (I limit myself to using an 8 foot ladder). Once a tree grows too tall, I let the tree grow naturally. My only pruning at that point is to remove lower limbs to make working under the trees easier.