Northern Pecans

Last year, I placed 9 bark grafts in a large tree in an effort to change a seedling tree into tree that would produce large, high-quality nuts (photo at right). Today, I spent nearly 90 minutes up in a hydraulic lift moving from graft to graft, trimming each graft union, and removing new sprouts growing on the trunk and main scaffold limbs. I can't imagine how long this task would take if I had to use a step ladder to access these graft unions.
The hazards associated with grafting, pruning, and training a top-worked tree from the top steps of a ladder are obvious. No tree is worth broken bones and a extended recovery period. If you would like to graft a seedling tree that has grown too large for conventional grafting methods or you end up changing your mind on a previously grafted tree, consider coppicing the tree at ground level.

The practice of coppicing works pretty well for trees that have not grown over 10 inches in trunk diameter. Out in our pecan breeding plot, I've been removing trees that produce poor quality or scab susceptible pecans. As a result I have produced dozens of coppiced trees. The photo at left shows the current size of many trees in the breeding plot compared to a tree that was cut at ground level a couple of years ago.

In the two years since cutting the tree at ground level the tree has sprouted multiple stems from the stump (photo at right). The tallest sprouts have already grown to over seven feet in height. These fast growing shoots make excellent sites for bark grafting, and I can even make the graft with two feet firmly on the ground.

Take a close look at the sprouts growing from the coppiced tree (photo at left). The sprouts are all growing from around the outside edge of the stump. These sprouts actually arise from epicormic buds buried under the bark of the stump.

Before grafting this tree, I trimmed off all but the most vigorous sprout. Using my chain saw I cut off all competing sprouts at the same height as the stump (photo at right). The white wood in the photo reveals the location of the removed sprouts. The dark (stained) wood is the original tree stump.

Once all competing sprouts are removed I have what looks to be the perfect tree for bark grafting (photo at left). But be forewarned. The stump will produce additional sprouts this coming summer and I'll need to add stump-sprout removal to my list of summer pruning tasks.

I usually recommend leaving a couple of lower limbs below a bark graft. However, this sprout had grown so rapidly that the lowest limbs were all above my preferred graft height. I figured that this tree had already survived coppicing, so a brutal cut for placing a bark graft couldn't hurt. I placed the graft at a comfortable height for both grafting and for summer training of the sprouted scion. Judging from the vigor of the stump sprout, this scion should make at least 4 to 5 feet of new growth this summer. I'll need to watch this tree carefully. Summer pruning to ensure a central leader and careful tying to a strong stake will be critical for graft success.

     This year, I made my first pecan graft on Sunday April 24th. Exactly three weeks later (May 15th), I checked on one of those early grafts and found buds bursting from the scion (photo at right).
     During the past three weeks I've been grafting pecan trees almost every day. I've grafted trees at the Pecan Experiment Field, during grafting schools, and on my own farm. The weather forecast for this coming week is cloudy, wet, and cool--great grafting weather. At every break in the rain, I'll be outside grafting even more trees.
    One of the most frequent questions I receive during grafting schools is--"How long can I keep grafting?" The answer, like almost every outdoor activity, is that it depends on the weather. The grafting season ends when daytime high temperatures start to climb into the low 90's F. High heat seems to literally cook newly placed grafts to death. In the past, hot weather occurred as early as mid-May in SE Kansas. Most years, the heat will hold off until June.
    I watch the long range forecasts to see when weather experts predict the first real heat wave. If a week of mild temperatures is forecast before the heat hits, I'll keep on grafting. If a heat wave is immenant, making additional grafts is not a good idea.

I was driving through my orchard when I noticed a young, grafted tree that looked more like a tree straight out of a Dr. Seuss book than a pecan tree (photo at right). As strange as this tree looks, this type of growth pattern is not that unusual for a pecan tree. During late summer of the previous year, a cluster of closely spaced buds formed at the terminal of each branch (including the central leader). This spring, these buds began growth and formed a profusion of new shoots right at the ends of each branch. Left to grow unchecked these shoots will compete for predominance and you will end up loosing your central leader.
At this time of year, a few judicious pruning cuts will help direct the new growth of this tree and help maintain a strong central leader.

I always start at the top of the tree and select a single new shoot to be my central leader (photos above). Before pruning you can see the top of this tree has 5 actively growing shoots. I selected one of these shoots to be the new central leader and pruned off all competitors. In fact, I removed all shoots within two feet of the apex of my new central leader. This helps preserve the dominance of the new leader.

Next, I move down to the side shoots. Once again several buds broke at the terminal of last year's wood. For side branches, I remove any upwards growing shoots (red arrow) and retain outward growing shoots. After these outward growing shoots grow two feet of new growth, I'll tip prune the terminal bud to slow down the extension growth of these side limbs.

The lateral branch on the left side of the tree had two upward growing shoots that needed to be removed (red arrows). With just a couple of snips with my pruning shears, I was able direct the growth of this lateral branch outwards rather that upwards (upward growing shoots will compete with the central leader).

Standing back away from this tree, it looks like I have a tree with a lot of blind wood (branch area not supporting new foliage). However, on close inspection, many buds along these stems were beginning to break bud (photo at right). As the growing season progresses, these new shoots will continue to grow, helping to fill out the canopy of this young tree.

After directive pruning, this young tree has lost the heavy profusion of leaves at all the terminals. I now have a single central leader and outward growing lateral limbs. By mid summer, this tree should develop additional lateral branches that will help fill out the tree's canopy

Last month, I received my copy of "Pecan South" which featured a photo of a young tree on the cover (photo at right). One look at the photo and I couldn't help but think this tree had received zero attention since it was planted. The tree had a nice straight trunk that was topped by a cluster of branches growing in every direction. The tree had already lost its central leader.
How can such an obviously strong growing tree lose its central leader so quickly? Yesterday, I was pruning some trees I grafted last year and I think I discovered the answer.

The tree pictured at left was grafted last year. After making some judicious directive pruning cuts last summer, the scion grew a nice straight trunk over four feet in length. However, this spring, the tree burst forth with new shoots from every bud near the top of the tree. If I had let nature take its course, I would end up with with a tree looking very much like the one on the cover of the magazine.

Take a closer look at the top of my young tree (photo at right). Growing from the top of last years wood are at least a dozen new shoots with no one shoot showing any dominance to make a central leader.

An even closer look at the terminal of last year's growth reveals just how many new shoots are growing at the top of the tree. My job now is to identify one of the new shoots to become a central leader and to prune out all others.

I choose to keep a strongly growing shoot that was growing out about 3 inches below the upper-most whorl of new shoots. With a single cut, I could remove a lot of the excessive shoot growth (photo at right).

Next, I followed the 2-foot rule. I pruned off all lateral branches that emerged from the central leader within two feet of the new central leader (photo at left).

After making just these few summer pruning cuts I was left with an actively growing shoot that will become my new central leader (photo at right). Later this summer, secondary buds will break along the main stem to form well-angled lateral branches and to help fill out the tree's canopy.

Over the years, I have learned that leaving a single tender shoot suddenly exposed to our strong Kansas winds usually not a good idea. Within days, the exposed green shoot often snaps off in a strong gust of wind. So just like training the shoots growing from a new graft, I used electrical tape to attach a bamboo stake to the woody portion of the tree, then used flagging tape to tie the new leader to the stake (photo at left). Staking the new shoot helps to straighten up the new leader and will prevent both wind and bird damage.

Its been a month since I started grafting pecan (and hickory) trees. So far, it looks like I have a perfect success rate with many grafts already pushing out new shoots (photo at right). One of the most overlooked keys to preserving graft success is taking the time to come back to each grafted tree and trimming off the trunk sprouts that emerge below the graft union. So yesterday, I started inspecting each graft armed with my trusty pruning shears.

In the photo at left, you can see that I have a successful bark graft growing on a fairly large seedling tree. Below the graft union, numerous trunk sprouts have also started to grow. Note that the leaves of these sprouts are reddish in color. Red pigmentation on new leaves is a common characteristic of a juvenile pecan tree. The sprouts growing from the scion are pure green indicating that these shoots are growing from sexually mature tissues (ready to bear nuts). To make sure the tree focuses its energy on growing scion shoots, I used my clippers to remove all trunk sprouts. I also pruned off any upward growing shoots sprouting on side limbs that I left on the tree to provide photosynthetic energy to the root system.

A month ago, I placed a hickory scion on a small hican rootstock using and arrowhead graft (photo at right). The hickory scion has sprouted nicely but the rootstock has already sprouted extremely vigorous shoots that are growing at a rate that would soon engulf the scion. That's the problem with not getting back to inspect grafts several times during the summer. Some trees try to grow around a scion rather than invest tree energy into growing a "foreign" shoot (the scion). The quicker you get competing trunk sprouts pruned off, the more tree energy will be forced into the growing scion shoots and more wood with be formed to grow over the graft union.

Yesterday, I spent some time scouting the orchard to get a feel for the 2016 pecan crop. All of the pistillate flowers have been pollinated and I was encouraged when I found a cluster of five nuts on a Kanza tree (photo at right)

    However, most pecan nut clusters have 3 to 4 nuts at this time of year. Look closely at the nut cluster pictured at left. Above the 4 nuts in this cluster you can see an empty flower stalk (red arrow). This portion of the pistillate flower inflorescence had also produced additional female flowers that have since dropped off the stem. Look closely enough and you will see a nut attachment scar on the stem that indicates the position of the now aborted flower. Now look at the very top of the stem. You should see four small sepals and a rudimentary pistillate flower stigma. This is an example of a small, poorly-formed flower that would never have the strength to become fertilized or grow into a pecan.
   This single photo can help explain how pecan trees create flower clusters and why some flower clusters are larger than others. Pistillate flower stalks are formed at the end of the current seasons new grow. The number of flowers produced and the ability of those flowers to remain viable is determined by the energy stored in last year's wood. Given enough plant energy, a current season's terminal will start creating pistillate flowers and continue producing new flowers up the stem until the shoot basically "runs out of gas". Flowers near the base of the flowering stalk are the strongest and are the most likely to become fertilized and produce a viable pecan. As the tree produces additional flowers, the tree gets to a point where it only has enough energy left to produce small or poorly formed pistillate flowers. These poorly formed flowers drop from the tree during the final stages of the pollination season.

The amount of energy a shoot has available to create female flowers is largely determined by the general health of the tree and by the previous season's crop load. A heavy crop load can drain the tree's energy reserves to a point where a tree finds it difficult to produce viable female flowers or even initiate a pistillate inflorescence during the spring following a heavy crop the previous fall. The photo at right shows a flowering stalk that has dried up and all pistillate flowers have aborted (red arrow). Although this shoot had enough energy to initiate flowing, the size of this flower stalk indicates that the flowers were all small and weak.
Many might think the lack of nut set on this shoot was due to a lack of pollination. However, pollination has nothing to do with the abortion of the flowers on this terminal. Weak and poorly formed flowers will never produce nuts regardless of the amount of pollen flying through the air.

This year, I've also seen some trees that never bothered to try to create a pistillate flower clusters. Totally vegetative shoots are easy to spot at this time of year because they are still elongating and setting on new leaves (photo at left). Trees covered with vegetative shoots this year are setting themselves up for a massive nut crop next year.

A few weeks, back I showed how I converted a multi-stemmed "pasture" pecan tree into a single-stemmed grafted tree. Yesterday, I came back to this tree and found that the scion had budded out (green buds) but the graft-union was surrounded by vigorously growing shoots growing from the rootstock (reddish colored leaves) (photo at right). Like most bark grafts, the trunk below the scion developed numerous trunk sprouts. In addition, all the stems I previously pruned off at the ground level had begun to resprout, creating a forest of new shoots adjacent to the stem I had selected for grafting. All of these red-colored shoots will need to be pruned off in order to force the growth of the scion.

   Once the rootstock sucker growth was removed I was left with a single trunk and a budding scion (photo at left). However, I'm sure that I'll need to visit this tree often because the large root system under this "pasture" pecan tree will continue to push up new shoots from just below the soil surface.
   I call this tree a "pasture" pecan tree because this tree had been mowed down year after year during hay harvest. Even though the top of the tree was removed annually, the root system continued to grow in size. Once all haying stopped, the tree burst forth with multiple stems and rapid growth.
Because this tree has the potential to send up numerous root sprouts, I'll need to be extra careful in using herbicides to control weeds around this tree. Systemic herbicides like Roundup, Liberty, and Remedy could easily enter the tree via hardly-visible new root sprouts and cause tree damage or even tree death.
    However, the benefits of weed control around young pecan trees is well known. Grasses can be controlled safely with a grass specific post-emergent herbicide like Select. To suppress broad leaf weeds and any new rootsuckers, I plan to use the non-systemic, burned-down herbicide, Gramoxone. Since Gramoxone works by desiccating live tissue, I will need to be careful not to get this herbicide on the trunk of my tree.
    Eventually, the scion will grow to dominate and will start to inhibit the growth of additional root sprouts. Once that happens, tree maintenance and weed control will be much easier.

I was working with my young pecan trees and was making some directive pruning cuts when I stopped to photograph a couple of the techniques I use in training trees.

I always start at the top of the tree to make sure the tree is still growing a single central leader. By the first of June, this young tree (2nd summer after grafting) had already added over three feet of new growth to the leader but I spotted trouble already. Look carefully at the photo at right and you'll see a stalked bud at each node. Allowing these stalked buds to grow would be a guaranteed way of losing the central leader in a thicket of narrow angled branches.

The easiest time to remove stalked buds is right after they form on soft and green shoots. To remove the stalked bud, I just grab the bud with my fingers, pull the bud to one side of the stem, and snap off the bud (photos above). Wait a couple of more weeks to perform summer pruning and you will need a pair of clippers to remove fully formed and hardened stalked buds.

After addressing the central leader, I move down to the lateral branches. Following the 2 foot rule, I headed back all the lateral branches that had already exceeded 2 feet of new growth. When making the heading back cuts, I always prune to an outward growing bud (photos above). In this case, I was also careful to remove the stalked bud when I made the cut. Heading back existing lateral branches will help keep the tree more compact and will promote the growth of new lateral branches along blind portions of the central leader (areas well below the top of the tree that lack lateral branches).

    We began spraying for pecan nut casebearer this morning (photo at right). After discovering 1% cluster damage yesterday and checking the weather forecast for the next week, I decided we better get started.
    Temperatures for today (June 9) thru Sunday ( June 12) are predicted to reach the low 90's each afternoon. Insect development is stimulated by warm temperatures so this year's casebearer infestation should build quickly. In addition, rain is forecast for early next week so I added a fungicide to this spray to provide protection against infection by pecan scab.
    For casebearer control, I decided to use up some of the insecticides we had on hand. Part of the orchard will be sprayed with Eraser (Chloropyrifos) and part with Warrior II (lambda-Cyhalothrin). For a fungicide, we applied Quilt which has two active ingredients: propiconazole and azoxystrobin. We also added a non-ionic surfactant to the spray tank.
   We like to get started spraying as early in the morning as possible. At this time of day, the winds are calm and the humidity is high. Both of these factors contribute getting better coverage of the leaves throughout the entire tree canopy. You can see in the photo above that early morning spraying creates a mist that swirls through the canopy covering both upper and lower portions of the leaves.

I set on a lot of bark grafts this year and the scions are growing like mad (photo at right). So far this year, I've already made one pass through the orchard to prune off trunk sprouts in and effort to force new growth on the scions. Now with plenty of new shoot growth, its time to select my new central leader and prune the scion down to one shoot.

Two buds have grown from the scion, both creating strong shoots (photo at left). To develop a tree with a single central leader, I'll need to prune off one of these two shoots. Some growers like to leave multiple scion shoots on the tree all summer long. Then, late next winter, they will prune the scion down to one shoot and harvest the extra shoots for scionwood. I like to make the choice for a new central leader as soon as possible. Pruning down to one shoot in mid-June gives me the entire summer to grow a strong and dominate central leader.

With a single cut, I made my selection for a central leader (photo at right). When choosing which shoot to save, I choose to keep the strongest growing shoot. About 80% of the time, the strongest shoot will arise from the lowest bud on the scion.

Its amazing to see how much a scion can grow in diameter in just a few short weeks. After trimming the scion down to one shoot, I noticed how much strain the green grafting tape tied around the scion was under. To relieve the girdling pressure of the tape, I used my knife to cut off the tape, while leaving the rest of the graft wraps in place (photo at left).

When making a bark graft, I often leave a nurse limb on the tree under the graft to help provide photosynthetic energy to the root system. But when leaving a nurse limb on the tree, I also make sure that upright sprouts don't develop along that limb that could compete with the graft. In the photo at right, I've used red arrows to point out several upright sprouts that have developed on my nurse limb. Once these shoots are removed, the graft will continue to grow without any direct competition.

The new scion shoot on this graft is growing so rapidly that it already developed stalked buds (photo at left). I used my fingers to grab these elongated buds and pulled them off the tree. Not surprisingly, I found stalked buds at every node on the new shoot, from the very base of the shoot to the apex. I removed them all.

On another graft, I found the new scion shoot had terminated with a flower cluster (photo at right). In this case, I pinched off the flower cluster and left the adjacent stalked bud in place (red arrow). This elongated apical bud will become the primary growing point for the scion's central leader. The stalked bud I left in place will quickly resume extension growth originally stalled by the formation of pistillate flowers.

Today, I spotted a newly hatched colony of fall webworm larvae on a young tree (photo at right). The larvae are so small at this time that are unable to chew up the entire leaflet. Instead, these newly-hatched larvae simply scoured the surface of the leaf turning it light brown in color.
The larvae have already constructed their dirty-white web to protect the colony from predators and parasites. In the photo, you can see that the web currently covers just two leaves. I controlled this colony by simply cutting off the two leaves, removing the entire colony from the tree, and squashing the insects under foot.
At this point in the growing season I have not noticed many fall webworm colonies. The colonies I have seen are generally located on trees that did not receive an insecticide treatment for pecan nut casebearer 10 days ago.

I was trimming up some young trees when I came across a seedling tree that had leaves sprinkled with light green galls (photo at right). These galls are formed by the plant in response to the feeding of an insect called the pecan leaf phylloxera. I find leaf phylloxera most commonly on juvenile pecan trees that have not yet been grafted.

I photographed a couple of leaf phylloxera galls on the upper side of the leaf blade then flipped the leaflet over so you can see the same galls from the under side (photo at left). On the upper leaf surface the galls a raised, irregular-shaped and smooth. On the lower side of the leaf, the galls are raised with a nipple-like projection in the center of the gall.

I cut open one of the galls, then photographed both halves (photo at right). The gall was filled with aphid-like insects. I found both winged adults, and wingless nymphs inside the gall. These small insects feed on pecan plant tissues that make up wall of the gall.

Eventually the gall splits open on the underside of the leaf allowing winged adults to leave the gall (photo at left). After winged adults mate, female phylloxerans will find a secluded spot in the rough bark of the tree to over winter.
I usually don't bother trying to control these insects on juvenile pecan trees. Once I graft the tree, the problem seems to disappear.

Last week I scouted the pecan grove for pecan scab. For the most part, our trees look pretty clean. I had a hard time finding scab lesions on any part of this year's new growth. However, when I walked over to trees of some extremely scab-susceptible cultivars, new scab lesions were present on some of the foliage (photo above). Dooley, Hirschi, and Maramec were covered with scab last year but this year, with a drier than normal month of June, scab lesions were confined to only certain leaves and on the upper leaflets of those leaves. This kind of uneven distribution of scab lesions on foliage can be explained by the simple fact that the scab fungus prefers to attack rapidly expanding new plant tissue. For a short period during the leaf expansion phase of spring growth, weather conditions became perfect for the release of pecan scab spores. When those spores landed on leaflets that were still expanding, they were able to infect the new tissue and create a fresh scab lesion.

When most growers think about pecan scab, a mental picture of blackened pecan shucks and small pecans comes to mind. However, scab can cause major problems with the foliage. Scab lesions can form on the rachis of the leaf and effectively cut off water and nutrient supplies to a leaflet. In the photo at right, The terminal leaflet of one leaf has fallen off due to scab while on the other leaf several leaflet have dried up and dropped off the rachis.
Under growing conditions in SE Kansas, foliar scab is primarily a problem on severely susceptible pecan cultivars (Dooley, Hirschi, and Maramec). Scab is so bad on these cultivars, I've begun the process of eliminating these cultivars from our grove.

The main reason for scouting for scab last week was to see if the fungicide we applied with our casebearer spray was effective for keeping scab lesions from forming on nuts. The photo at left shows a cluster of Dooley nuts. As of last week, small scab lesions had formed of leaves, leaf rachii, and the pedicle of the nut cluster. The nuts remained free of scab.
On Monday, June 27th, we received an inch of rain from two separate rain showers (early morning and late afternoon). Our temperatures have remained warm in spite of the rain and the increased humidity has made ideal conditions for the spread of scab.

Today, the day after the rain showers, we started up the sprayer first thing in the morning to apply a fungicide to our trees (photo above). Since it looked like we had a short window of opportunity to spray this week (additional showers are forecast for Thursday, June 30th thru Sunday July 3rd), it was very important to get a systemic fungicide on our pecan trees to protect our crop. We applied Quilt Xcel at the rate of 19 oz/acre.

Earlier this year, I showed you how to use directive pruning to prevent a tree from developing a bushy, leaderless top. The photo at right is a great example of what can happen when a bushy, multi-stem top is allowed to grow unchecked. After the foliage of this tree was soaked by a recent rainstorm, the added weight of water on the foliage was enough to bend the tree down to the ground. Fortunately, the main trunk did not break but this tree needed my immediate attention.

Since the top of the tree was so close to the ground, I took a quick photo of the tree's apex (photo at left). I count five new shoots growing out of the top of last year's wood. With all that new growth at the very top of the tree, it is no wonder the tree became top-heavy during a rain storm.

Fixing this tree was a two step process. First, I pruned the top of the tree. I selected one shoot to be the central leader then employed the 2-foot rule to prune the rest of the tree. I did all this pruning while the tree was still bent over on the ground (no need for a ladder!). The second step was to install a ten foot tall tree training stake to hold the tree upright. I attached the stake to the base of the trunk using some white electrical tape (white? its just what I had on hand). Next, I lifted the tree up and used additional wraps of tape to hold the tree in place against the wooden stake (photo at right). As this tree increases in diameter over the summer, it should gain enough wood strength to hold itself up without the wooden stake.

Yesterday, I spent the morning trimming grafts and training the scion to a nice central leader. Just two weeks ago, I worked on these same trees selecting a single scion shoot and removing stalked buds. However, it is amazing how fast bark grafts can grow. Many grafts had grown 10 to 12 inches taller in just two weeks. Along with the new growth, the tree also developed new stalked buds (red arrows point to stalked buds in photo at right). My first step in training these grafts is to remove all stalked buds. Next, I used flagging tape to tie the new growth to the bamboo stake I already had in place.

When I remove stalked buds I always start at the top of the scion shoot and work my way down. At some point, I will come the location on the shoot were I had removed stalked buds previously (2 weeks ago in this case). You need to watch carefully as you tear off the stalked buds. In the photo at left, the red arrow points to a stalked bud that has developed since the last time I removed stalked buds. This bud will be removed.
The yellow arrow points to a brown scar on the stem indicating the position of a stalked bud that I removed 2 weeks ago. Below the scar is a secondary bud that is starting to grow. I will leave this bud in place to form a wide angled lateral branch. Remember, by the time a secondary bud starts to break, it will be located well below the central leader and in perfect position for lateral branch formation.

Grafting pecan trees is one of my favorite parts of developing a new orchard. After years of practice, I can graft fairly quickly and I have confidence that the graft will be successful. The time consuming part of grafting trees actually occurs during the summer months. Every 3-4 weeks, I return to each grafted tree to prune off trunk sprouts, tie the scion's new shoot to a bamboo stake, and remove stalked buds. The photo at right is an example of a successful graft I made earlier this year. Look carefully, you can see that I've already tied the new growth to a bamboo stake with green flagging tape in 3 places.

I can not stress enough the importance checking on the growth of your scions regularly throughout the summer. The photo at left is an example of what can happen when the scion grows faster than expected, the new growth wasn't tied to the bamboo stake, and a thunder storm blows through the orchard. Without being tied to the stake, the wind broke off the scion right at the top of the stock.
With this tree, I'll let the stump sprouts grow and re-graft the tree next year. I'll also leave the bamboo stake and all the graft wrapping in place to remind me that this tree needs re-grafting.

I've been watching the weather and monitoring our pecan grove trying to keep to top of possible pest problems. I'm really worried about scab get started on our nut crop. Scab infections can spread rapidly on pecan shucks during the period of rapid nut growth that occurs during July. We have received numerous rain showers since the last time we made a fungicide application and the time has come to apply another protective layer on fungicide on the nuts (2 weeks between sprays).

In scouting our pecan grove, we've seen three insect pests that I would like to keep under control. The first is fall webworm (photo at left). We don't have an overwhelming webworm problem in the orchard but there are just enough first generation colonies that, if left untreated, may lead to a huge second generation problem in August.

We have also collected several dropped nuts damaged by hickory shuckworm You can identify hickory shuckworm damage by finding an ovipostion scar surrounded by a ring of white insect scales (photo at right). With a low to moderate crop this year I want to make sure we hold onto as many nuts as possible. Controlling hickory shuckworm will help maintain the current nut set.

The third insect pest we have found in our pecan grove this week is Japanese beetle. This is a new pest for us and one that is just starting to move into our area. This shiny green beetle with copper-colored wing covers, usually feeds in groups of several beetles. Pecan leaves take on a tattered appearance following beetle feeding.
In spraying for pecan scab today, we included an insecticide in the spray tank to make sure we keep webworm, shuckworm, and Japanese beetle under control.

July is the month when northern pecans enter a period of rapid fruit enlargement. Even though pecans are a nut crop, we call it fruit enlargement because the shuck and seed within are collectively termed a pecan fruit. Botanically, pecans are similar to peaches. The hard-shelled seed of a peach tree is surrounded by a fleshy outer-layer that we just love to eat. However, we discard the peach pit or seed. With pecans, we disregard the fleshy outer-layer and eat the seed within.

On Thursday, July 21, I collected a few pecan fruit from several cultivars to check on the status of fruit enlargement. The first group were pecans from early ripening cultivars (photo above right). Cutting open these nuts I found that these nuts ranged in kernel development from 1/4 water stage (Colby) to nearly full water stage (Warren 346).

The next group of cultivars had pecans that were all very similar in size at this point in the growing season (photo at left). However, these cultivars represent a wide range of ripening dates. At harvest, Peruque will be the smallest nut while Maramec will be nearly twice the size of Peruque.

After cutting open each nut, I could see differences in kernel development (photo at left). Peruque was at 1/2 water stage while the Maramec kernel was still at the small heart stage. The Faith and Waccamaw nuts were approaching 1/4 water stage.

The final group of nuts I collected were from four scab free cultivars (photo at right). The Kanza and Hark nuts looked plump and well on the way to full fruit sizing. Lakota looked narrow and not as far along. Oswego, a nut that at harvest will be similar in size to Kanza or Hark looked significantly smaller.

Cutting open each nut I found Kanza and Hark to be at 1/4 water stage. The Lakota had slightly less kernel development. But Oswego kernel development was far behind, still at the small heart stage.

A strong wind during a mid-summer thunderstorm can undo years of careful tree training.This was the case when I discovered a tree broken over and laying on the ground (photo at right).

It seems the force of the wing was so strong that it bent the tree over so far that the main stem fractured into hundreds of splinters (photo at left). Fortunately, I paint the graft union white on all my trees to provide an easy visual record of which trees are grafted and which are not. This tree broke well above the graft union so I could use one of the small branches below the break to serve as a new central leader.

After looking over the tree, I decided to cut the damaged trunk off just above a small lateral limb. At first, I thought it would be a good idea the start cutting at a point just above the side shoot (photo at right). However, cutting into the curve of the break meant that all the downward force of the broken tree was working to bind the saw in its kerf. I quickly pulled the saw out and opted for a different angle of attack.

By cutting the tree on the back of the break, I soon learned sawing through the wood was much easier (photo at left). The weight of the fallen tree was pulling open the saw kerf allowing the saw blade to move freely. However, cutting from this direction meant that I had to draw an imaginary line across the stem so I would finish the cut just above the point that little side branch. I also needed to trim this trunk at a 30 degree angle just like we do when trimming up a bark graft.

After making the angled cut across the trunk, the tree looks just like a recent bark graft (photo at right). However, unlike a bark graft, I decided to leave emerging stump sprouts above the graft union to grow for the rest of this summer. This tree has suffered a tremendous loss of leaf area in the middle of the summer and these emerging shoots will help shade the trunk to prevent sun scald to the trunk. Next year, I'll go back to proper pruning and training to make sure I develop a well structured tree.

To help train the remaining small side shoot into a new central leader I drove a 1 x 2 inch wooden stake in the ground next to the trunk. I then secured that stake to the trunk of the tree with black electrical tape. Next, I carefully lifted the side shoot to an upright position. If I pulled too hard, I ran the risk of breaking the shoot off the tree. After pulling the shoot upright, I used green flagging tape to hold the branch in position (photo at left).
It will take a couple of years to heal over the wound created by the break in the trunk. I'll keep the new central leader tied to the stake until the healing process is complete.

We received nearly 2 inches of rain earlier this week and I though that the sudden jolt of soil moisture might kick pecan nut development into high gear. So today, I collected some nut samples of several cultivars and cut them open to check on the progress of kernel development.
The first group of nuts I cut open included samples from Posey, Pawnee, and Kanza (photo at right). The kernels of Posey and Kanza were at 1/2 water stage while the Pawnee was not as far along. This came as a surprise because Pawnee normally ripens before Posey and Kanza in the fall and I had expected to see more advanced kernel development at this time during the summer. I'll be cutting more nuts in the weeks ahead so we'll see if this year's Pawnee crop stays behind in terms of nut development.

The second group of pecans I cut open included cultivars that are becoming mature trees in our cultivar trials. Surecrop and USDA 61-1-X had kernels at 1/4 water stage (photo at left). The Jayhawk nut was in the large heart stage and the Caddo nut showed a kernel in the small heart stage. This Fall, Surecrop and 61-1-X should ripen by early Oct. Jayhawk will ripen at the same time as Giles, in Mid Oct. Caddo will ripen late, splitting shuck in late Oct. or early Nov. Some years, Caddo nuts fail to ripen before our first hard freeze.

Coppicing before re-grafting a large pecan tree

How long can I keep grafting?

Directive pruning a young pecan tree

Tree training: Directive pruning now helps avoid major pruning later

Forcing scion growth on new grafts

Pecan crop load and pistillate flower strength

Trimming up the "pasture" pecan graft

Summer pruning: Techniques up close

Spraying for pecan nut casebearer

Training new pecan grafts

First generation fall webworm hatching

Galls on seedling pecan trees

Monitoring pecan scab and making the decision to spray

Don't let pecan trees get top heavy

Be careful when pulling off stalked buds

Preventing wind damage to new grafts.

Hickory shuckworm, fall web and scab: Time to spray again

Pecan fruit sizing during July

Storm damages young pecan tree

Pecan development: 28 July 2016