24 Attachment(s)
How to Top Work a Pecan Tree to Change It's Variety
I'm making a totally separate thread with this subject since it is heavily researched by Grafters.
Attachment 486697
I harvest my Pecan tree Scions in February. These were stored in a refrigerator set to 40 degrees (one I use for this purpose mostly). You want healthy first year's growth, pencil diameters seem to work best, straight sticks if possible, I like the larger buds on the Scion wood but the small ones grow into new limbs too, and add 1/2 a damp paper towel (very rung out) to the bag if it will be a while before you will use. I don't use added moisture but harvest my Scions the day after a rain. Seems they don't mold as easy.
Attachment 486698
Tools of the trade. This folding saw has been in service for I don't know how many years but it has top worked over 150 trees most much larger than the example today. 91% Alcohol for disinfecting all cutting implements. Various Grafting Knives, I'm left handed and most knives are for right handed people. Reason they are Left & Right handed is a grafting knife blade is only sharpened on one side. Videos online show the technique to properly prepare the scion using the proper grip and cutting technique. Linerless Self Vulcanizing Tape is my go to product for sealing my graft work today but I along with many others have enjoyed great success using Duct Tape too. Jumbo Rubber Bands really improve the success rate over Duct Tape when it comes to keeping compression on the graft till it heals. Aluminum foil is used to reflect the Sun's heat, and Grafting Wax is used to seal & waterproof your work.
Attachment 486699Attachment 486700
Your pruners must be clean and disinfected. Here are mine after pruning all my fruit trees of broken limbs from the Tornado recently. All that sap on the blade needs to be removed. I use a red Scotch brite pad to keep my blades clean.
Attachment 486701
Now to the task. This Pecan tree was struck a glancing blow on it's side by a falling pine tree from the neighbor's property. The pine was not real big and the Pecan tree was 10-11 inches in diameter where it was struck. I didn't think much about it but the Pecan started dying on that side first. By winter it was dead over 1/2 way thru. I decided to cut it down but leave enough of the trunk sticking up that if it survived till spring sunlight shining on the stump bark remaining would make the roots sprout suckers. The bet paid off. I allowed all the suckers to develop around the stump keeping the stump alive all the way around but kept upwards growth regulated by way of topping all the sprouts but one. Eventually by last winter I had removed all the extra suckers as the remaining developed enough to ensure the stumps survival.
Attachment 486702Attachment 486703
Not the greatest picture but you get the point. I topped the strongest shoot leaving 2 branches below my cut. The remaining branches will continue to draw nutrients from the stump keeping this sucker alive till the graft heals. Now after you saw off the top a bit of knife work here goes a long way. I shave the top of the cut all the way around with a very sharp knife. This makes the bark graft heal much better than a rough saw cut alone.
Attachment 486704Attachment 486707
After choosing the first Scion a fresh cut is made at the bottom then a bevel cut is made on the opposite side on the lowest bud.
Attachment 486705Attachment 486706
next on a flat part of the tree you made a vertical cut a little longer than you Scion bevel cut. Using the knife blade itself or the Bark Lifter (the bump on the top of the blade) you open the cut helping start the Scion to be inserted.
Attachment 486708
Over the years I have discovered a little extra Scion bark prep helps me maintain a almost 100% success rate top working Pecan trees. I square my blade to the Bark and lightly scrape the outer bark away revealing the Cambium underneath before inserting the Scion. This provides a superior amount of Cambium contact between the Tree & Scion.
Attachment 486709Attachment 486710
When first inserting the Scion into the Bark leave quite a bit of the Bevel Cut showing on top of the Tree. This will be dealt with later.
Attachment 486711
To double my chances of success I add a second Scion. On much larger trees I have used as many as 6.
Attachment 486712Attachment 486713
After both Scions are in position I use the Linerless Rubber Self Vulcanizing Tape to wrap the graft well. I make sure and put enough tape to waterproof the work but never rely on just that.
Attachment 486714Attachment 486715
After the tape job is complete I cut the jumbo rubber band and wrap it tightly around the tape compressing all the work well. Once the rubber band is installed I tap the Scion wood down further till just a small part of the Bevel Cut is revealed improving Cambium contact even further. Then again I work to waterproof the work some more using the same tape.
Attachment 486716Attachment 486717Attachment 486719
To reflect the Sun's heat off the graft till it heals I use aluminum foil, here I'm cutting two slits opposing each other, I slide the remaining connected aluminum foil between the two Scions, and then wrap the aluminum foil very well around the entire worksite.
Attachment 486718Attachment 486720
Time for the real waterproofing and insect control. I use a scented candle heater to heat my grafting wax before applying all over the top of the graft and the tips of the two Scions. Many instruct you to use plastic bags but I have found if any excessive rain or bleeding of the tree sap and the bags rot the graft joint. Since I switched to this method to execute a Bark Graft on any tree I'm sitting at 100% success. I hope you find this information useful, Grafting can be a very rewarding hobby.
5 Attachment(s)
Example of Last Year's Topworking of a Pecan Tree
A successful Graft is just the beginning. Years of maintaining the tree's sprouting growth below the graft is needed so as much growth energy as possible can be directed to the new variety without washing the graft out from the inside with sap, without reducing the tree's natural ability to produce growth hormones & energy, also protecting the weak Bark Graft Union until the day comes that the Scion wood has grown to completely heal the top of the Pecan tree Stump. This tree below has not had its sucker growth pruned yet this year as well as trimming the Nurse Branches back to redirect more of the tree's energy into the Scions boosting growth.
Attachment 486795
Just get a load of all that suckering growth, not that the Scion's could handle all of that. The tree looks "Hairy". You can't tell the Scion wood from the Suckers.
Attachment 486796
Now you can at least make out where the Scion wood is located. Still if left in this stage little energy would be directed to our Graft Unions.
Attachment 486797
Here it is easy to see the Scion wood is very healthy just not growing as well as I think it could. In the past I have made the mistake at this very point to cut off the Nurse Branches thinking the Scion wood would start bolting upwards but no, without the Nurse branches providing something to use for growing the Scions they will just die back. You need a certain amount of nurse Wood to keep the tree in Vigor growing. Like Walking a Tightrope.
Attachment 486798
Hard to see but from the backside I have started removing Water Sprouts & Suckers from both Nurse Limbs leaving some energy producing growth for the Tree's overall health.
Attachment 486799
Here you can see I shortened the Nurse Branches as well as trimming them up. This is what you want to see, healthy growth but not too fast, Pecan trees are weak wooded to start with. Too fast of growth I have found the Graft Unions can't take our Tropical Weather and break. I hope these examples help promote better Top Working skills for whomever takes on the challenges of Top Working a tree.
5 Attachment(s)
Update to the Last Pecan Topworking Graft
This is a duplicate to the post under tree propagation. This thread is intended to follow the one Pecan tree graft and post maintenance to grow the graft out.
As a tree is Topworked the trunk tries to maintain a growth rate. This Stump root system is still very much alive so care must be taken so too much new growth is not removed. We want to keep the Stump growth vigor.
Attachment 487676
All the buds on both Pecan Scions have broken. Growth is usually a little slow to start with but these buds are not growing as fast as they should. Looking over the rest of the shoots from the stump I see numerous new growths with lots of vigor. Most are above the graft where A-Typical Dominance kicks in. Since I chose to place the graft at a lower point on the stump shoots than the others attention must continuously be paid to remove vigorous growth on the shoots to force growth out of the Scions.
Attachment 487677Attachment 487678
First to reduce the A-Typical Dominance I topped the tallest shoot back closer to the graft height.
Attachment 487679
These vigorous green shoots is sending hormones to the stump letting it know "We are Growing, keep feeding us" so they must be removed.
Attachment 487680
Here is a picture with the proper thinning of growth to send more energy to the graft area.
1 Attachment(s)
Better Picture of Bud Break on Scions
I managed a better picture of the pecan Scions so you can see every bud broke and is growing.
Attachment 487708
2 Attachment(s)
More New Growth Thinning Required
Lots of work going on here all over the property. I walked by the recently Top Worked Pecan Tree and noticed new growth had popped up all over the tree. This growth can not be allowed to remain as we need energy sent to the 2 scion I grafted into the bark. Here is a picture of the amount of growth I removed and the new limbs emerging from the scions.
Attachment 488297
New limbs are forming, soon leaves will pop too.
Attachment 488298
3 Attachment(s)
Further Training the Pecan Scion towards Dominance
While mowing around the pecan stump I'm resurrecting I noticed it was time to train the Scion once again. The fatal tree strike that killed the previous grafted portion on the stump took a year to kill the original tree. So does the repair by Topworking. Your work needs regular attention once a successful graft has been accomplished. Preventing the scion from being broken out by a bird, wind, critter, etc is necessary as well as keeping Nurse limb growth in check.
Attachment 491928
First I cut away the extra growth of the nurse limbs on the same shoot off the stump that I grafted on. While the scion's vigor was low I left 2 nurse limbs but the scion is taking off so I want to send more sap to the scion, it has healed & grown enough that now more energy is needed. My goal is to keep the scion growing at a faster pace but not so fast that the scion outgrows the strength of the joint. Slow is better than fast.
Attachment 491929
To help our scion with the competition I removed the nurse growth shielding the graft from direct sunlight. Since the leaves make the energy now the scion's leaves get the direct sunlight first.
Attachment 491930
I bought a bunch of pine 1x2's for scion support but recently had 2 grafts break due to the 1x2 breaking at a flaw in the wood. This scion I just supported with a heavy, galvanized, potted tree wire. It allowed me to shape the wire in a vise so it fit the scion perfectly. Duct tape was used to attach the wire to the tree trunk and tree ties was used (3) to attach the wire to the scion for lots of support.
More attention will be needed till the growing season ends so updates will follow.
2 Attachment(s)
A Good Example of a Full Graft Union
Quote:
Originally Posted by
SuperDave336
Looks good. How long does it take for the graft to be solid?
So the little scions will grow & grow till they completely take over the limb or trunk it is grafted on to. Here is 2 pictures of the same limb, one from each side. You can see the scion has completely grown to the limb. Till it's a union like this support is needed.
Attachment 491947Attachment 491948
This limb is Headquarters. The only graft other than this is the source graft. Now Headquarters is a little larger than Elliot, same shape, same shelling issues. It's slow to bare too. I did this limb to just keep the source wood around. This Pecan tree is 5 varieties.