Monday, April 29, 2019

Grafting a tree to produce scionwood

    Whenever I graft a large seedling pecan tree over to a new cultivar, I usually place a single graft on the central leader and leave some lower limbs on the tree to provide photosynthetic energy for the root system.  As the new scion grows, I slowly remove the lower limbs below the graft union (one limb per year). However, with the tree pictured at right, I wanted to create a tree that could produce as much scionwood (new shoots of the new cultivar) as possible. This means placing a graft on every major side limb as well as the central leader. I guess you can call this an "extreme tree makeover".
   My first step was to cut back all the major branches to provide me with multiple places to attach bark grafts (photo at left). The central leader was about 2 inches in diameter while the side limbs varied in size from 1.25 to 1.5 inches in diameter. At this point, it looks like I've made great place to hang my hat and coat.  
    It took a little time, but I placed 4 bark grafts on this tree (photo at right). I used my standard bark grafting method. When deciding where to insert the scions on the side branches, I made sure that I could work on the graft union without my tools bumping into the main trunk.
    Not only is a "de-horned" tree an ideal place to hang a hat but it makes a great place for birds to perch. To protect each graft I installed a "bird perch" on each graft. Using electrical tape, I attached a bamboo stake adjacent to the scion in such a way to prevent birds perching on the end of the scion and breaking them over (photo at left). 
    When completed, I had 4 grafts and 4 bird perches on one tree.  However, I could have grafted 4 trees in the time it took to graft this one tree. If I wasn't trying to build up some scionwood supplies, grafting the 3 lowers limbs would be a waste of time since all three would be removed at some point in the future (as the tree grows larger).
    The bottom line is that I'm just a grafting fool that loves to mess around with pecan trees and I like to give my neighbors something to talk about.

Wednesday, April 24, 2019

A great day for grafting pecan trees

    The weather today was overcast, cool, and damp--prefect weather for grafting. So, once the early morning showers moved off to the northeast, I spent the day grafting trees. I used two of the grafting methods I have described in the past; the 3-flap graft and the bark graft (follow the links for details). In this post I'll be showing these grafting methods again but this time I wanted to point out a few of the tricks of the trade.
     I don't try to start grafting until the leaves of the stock tree begin emerging. I also don't graft a tree until it has demonstrated a vigorous growth rate the previous growing season. The tree pictured at right put on almost 2 feet of new top growth in 2018 and is a perfect candidate to accept a 3-flap graft.
    In the past, several growers has asked about the proper height for making a graft. On small trees I always try to place the graft at a comfortable height for me complete a graft while sitting on my scionwood cooler. If you can't make the proper grafting cuts comfortably, your grafting success rate will suffer. I always choose the site for grafting first, frequently cutting the stock tree back drastically. I then rummage through my scionwood supply to find the perfect scion. In this case, a 3-flap graft, the scion should be about the same diameter as the stock (photo at left).
    In preparing the stock for the 3-flap, the technique calls for making 3 vertical slits in the bark. When I make these cuts, I keep my knife in the center of the stem and slice downwards making sure to follow any curvature in the stem. In the photo at right, you can see that my slit curves to the left about two inches down to follow the bend in the stem.  By keeping your slits right in the center of the stem on all three sides you will end up with three straight flaps.
    I always make the three shallow cuts on the scion before I try peel back the flaps on the stock (photo at left). I make sure that the cuts on the scion are deep enough to expose wood on three sides. When I see white wood, I know I've got cambium exposed.
    Once my scion is prepared, I peel back the three flaps, making sure that I only handle them of the very top edge. I use my clippers to hold down the flaps so I can remove the inner wood (photo at right). Once again, I try to keep my figures from touching the inside of the bark flaps.
    Before inserting the scion, I always start wrapping up the graft union (photo at left). A couple of wraps around the base of the flaps helps to create a bark "tube" that can accept the scion. I hold the tape tight while I force the scion in place.
    By holding on to the tape, the scion will sit inside the bark flap tube all by itself (photo at right). At this point, I check the alignment of the flaps of the stock and cut surfaces of the scion. Sometimes, I'll pull the scion back out, then rotate it to see it I can get a better fit. Once I'm satisfied, I'll wrap up the entire graft union.
    When wrapping a 3-falp graft, I pull the tape as tight as I can without snapping the tape (photo at left). My goal is to make sure that I press each bark flap up firmly against the scion and drive out all air gaps.
     Once the graft is firmly in place, I cover the graft with aluminum foil and a plastic bag (as I do with all my field grafts). Before leaving this tree, I attach a bamboo training stick to the tree below the graft union (photo at right). In a few weeks time, I'll have a growing scion that will need support and training to a central leader. I also cage all my new grafts to prevent deer from browsing on new scion shoots.
     Since the 3-flap is an almost fool-proof grafting method, some folks become temped to place multiple 3-flap grafts on a tree such as the one pictured at left. However, I don't recommend that practice because it gives the tree to many opportunities to grow around the grafts and you'll get week scion growth.
   Instead, I sit on my cooler and cut back the tree to around two feet and prepare to make a bark graft. I find that cutting a small tree back like this helps to force the tree accept my scion. Then, when the scion starts to grow, the new shoot grows so vigorously that training to a central leader is easy.
           Once I complete the bark graft, I make sure to attach a training stick (photo at left).  Fast growing bark grafts will needing tying to a training stick as soon as possible to prevent possible wind throw. I'll also cage this tree before moving on to my next tree to graft.

Thursday, April 18, 2019

Pecan catkins emerging

     Yesterday, I spent some time out in my pecan grove inspecting emerging leaves and catkins. Its much too early to see the kind of nut crop we are going to have in 2019, but by looking carefully at catkins I can determine a pecan tree's flowering habit.

    Pecan cultivars that shed pollen before their pistillate blooms are receptive are said to have a protandrous flowering habit. Cultivars that produce receptive female flowers before shedding their pollen have a protogynous flowering habit. Nature has designed pecan trees with two flowering habits to ensure that every nut produced by a tree has the hybrid vigor that results from cross pollination.
    In the photo above, Oswego is an example of a protogynous cultivar while Yates 68 is protandrous. Now look at the emerging catkins. The Yates 68 catkins are already quite large, seemingly developing  faster that the new leaves. In contrast, the catkins on Oswego are just emerging  while several new leaves are expanding on the new shoot.

      This distinctive difference in catkin appearance can been seen as spring growth continues.. The photo at left shows the protandrous Faith cultivar in comparison to protogynous Kanza. As a general rule the catkins of protandrous cultivars are short and fat while catkins of protogynous cultivars are long and thin.
    While inspecting my trees, I collected shoots from three protandrous cultivar and three protogynous cultivars. Since the time of bud break differs among cultivars, these photographs offer a glimpse at early shoot development.

    The first set of shoots were collected from protandrous cultivars (photo at right).  Starting with Hark, note that the catkins of protandrous cultivars emerge before the leaves start to unfurl. As bud break continues, catkins continue developing at a fast rate becoming quite large early in the season.
    The photo of protogynous cultivars (at left) illustrates that shoot growth starts of quickly while catkin development is delayed.  Remember that pistillate flowers are produced on the terminals of new shoots. So, early shoot growth is just a precursor of early female flower receptivity. Catkin emergence on protogynous cultivars seems much slower than new shoot growth.

Tuesday, April 16, 2019

Grafting this Spring

A successful apple graft
    Over the past week, I've been getting plenty of practice with my grafting knife by propagating apples and pears in our fruit orchard. Fortunately for me, the best time to graft apples and pears is usually several weeks before it is time to start pecan tree grafting. However, working in the fruit orchard has got me thinking.
     I know that several people are disappointed that my recent retirement means that I won't be traveling around Kansas, Missouri and Oklahoma to hold grafting classes. However, I will be doing plenty of pecan grafting on my own farm and would happy to demonstrate the techniques to anyone willing to drive to my place. As of today, it looks like I'll start grafting around April  27th. I do most of my grafting in the mornings and it should take me about 2 weeks to work all trees that are ready for grafting. So, if your interested, pick a pretty day and come see me in the morning. Our farm is located 4.5 miles east of Chetopa, KS on US Hwy 166 then south onto 95th Street. A sign for "Brenda's Berries" (our fruit business) marks the turn off the highway. As you drive south on 95th street, our pecan orchard is on the east side of the road. You should be able to see me in the pecan orchard grafting trees.
     In addition, I've been invited by the Indiana Nut Growers to hold a grafting class in southern IN. Hopefully, folks from IL, IN, KY and OH will find this grafting workshop worth the drive. Information about this meeting, to be held on May 18th, can be found by pressing the Events Tab above.
   One more thing. Several years ago I created a slide show showing the grafting techniques I use for grafting apples, pears and pecans. I have placed this slide show on a new page that you can access by pressing the Tab just below the mast head. You will note that I use some different methods for apples and pears I haven't presented in this blog for use on pecans. These fruit tree grafting methods are some of the oldest methods of grafting known to man but I don't recommend the splice graft and cleft graft for field grafting pecan trees.  

Wednesday, April 10, 2019

Controlling weeds in the pecan orchard

    Over the past week, I've been working on getting the weeds and grass controlled around my pecan trees (photo at right). It is widely accepted that total vegetative control around young trees is one of the key factors in promoting rapid tree growth and greater nut production.  There are several ways to achieve weed control around pecan trees including tillage, herbicides, and hardwood chip mulch. But in my orchard, I've opted for spraying herbicides.
      When I first started working with pecans back in the early 1980's, glyphosate (Roundup) was the easy choice for total vegetation control. All you needed to do was to make sure you didn't hit pecan leaves or green bark with the spray. However, once roundup ready crops were developed, the widespread use of glyphosate has led to the proliferation of roundup resistant weeds.
   This year, I have used a combination of herbicides around my trees. I used Gramoxone (a plant desiccant) to control existing winter annual weeds, and Simazine (a pre-emergent herbicide) to control germinating weeds and grasses. Later this summer, I'll come back with a broad spectrum contract herbicide to address any additional weed problems. I'll rotate between glufosinate ammonium  (Rely) and glyphosate (Roundup) to help avoid resistance issues.

     In my orchard, most of my trees started out as volunteer seedlings. So for these trees I drive a utility vehicle from tree to tree carrying a 25 gallon sprayer in the back (photo at left).  I try to create a 6 to 7 foot weed-free zone around each tree. I do not try to drive and spray at the same time. At each tree, I stop and get out so I can spray around each tree being very careful not to get any spray drift on the tree.
    Minimizing spray drift is very important when spraying around young trees. Last fall, I planted some one-year-old seedlings in some of the gaps in my volunteer orchard. I caged these trees to ward off the deer and carefully sprayed around the seedling (photo at right). When spraying near the small tree, I always ease up on the water pressure coming out of the nozzle. This dramatically cuts down the creation of a fine spray mist that can drift onto the green bark of the seedling.

Vegetation control is not so critical for the performance of mature pecan trees. The oldest trees on my farm are in the pecan breeding block which is planted in rows. Here, I spray a herbicide strip down the row using a simple one-nozzle boom sprayer mounted on my tractor. The herbicide strip has two functions. First, it serves to control climbing weeds such as poison ivy, trumpet vine, and wild grape. And second, it makes mowing the ground cover much easier. I can mow in one direction without having to try to weave in and out of the trees. In the volunteer orchard, I mow in two directions to get all the ground cover mowed. This means I'm covering the same ground twice every time I mow. 

Wednesday, April 3, 2019

Spring fertilizer application in the pecan grove

   With pecan buds swelling and the soil dry enough, today was a good day to spread some fertilizer on my pecan orchard (photo at right).
    Earlier this year I took a soil sample to test for phosphorus, potassium and soil pH. As I suspected and based on my soil type, the results showed I was low in P, K and lime. So today, I started by applying a complete fertilizer mix to my orchard. I spread 64 lbs/acre N, 46 lbs/acre P, and 45 lbs/acre K.
  You might recall, that I started this complete fertilizer regimen last fall and will continue until I build up the P and K levels in the soil until they reach sufficient levels according to soil tests.
   I also plan on getting some lime applied to the soil in the grove. My soil has dropped down to below pH 6 and I need to add lime to sweeten the soil back up to around 6.5. Once I contract a liming service, I plan on using a pasture harrow to rake the surface applied lime into the soil. I'll show that operation within the pages of this blog once I get the lime applied.