It is now almost exactly one year since Khuong Hoangduc of Vietnam showed us his simplified method of flat grafting (21st March, 2008). I have been using this technique for the last year and now I would like to tell you about my experience.
I originally thought the graft union might not be very strong and vulnerable to breaking off. When very young this is certainly the case but after about three months the grafts are reliably strong. I used to use this technique only when I had very little scion material and frequently made grafts with just a single eye as small as 2mm. Now owing to the ease and speed of the technique I am using this method for most of my grafts apart from the top of the scion which is impractical to use for flat grafting. Also the healed graft union is less obtrusive than with “V” grafts.
2mm flat graft The scion has grown to match the diameter of the rootstock
I used to cover the top of the scion with a fungicide, Ridomyl. But once this was not available and I had to use a blue fungicide. This was toxic to the scions and the whole batch failed. Since then I have not used any fungicide. Please remember that grafting is a surgical operation and as such everything must be as sterile as possible – plant material, knife, secateurs, bench and not least your hands. Swab (pro. swob) both the scion and rootstock in alcohol and let them dry to sterilize them before cutting. If I could get one out here in the wilds of Venezuela I would do my grafting in a sterile cabinet (0.2 micron filter), but that is impractical, so I have to rely on keeping everything as clean as possible. You will need some extra equipment:
1 Secateurs. I used to use my Felco 7. These are superb and have a handle which rotates as you cut. If you are doing a lot of grafting then this feature will prevent you getting a blister on your palm. But if you are only doing a little grafting then a simpler pair will be perfectly adequate. I personally would not use any tool which had any rust or blemish on it. Therefore you will need a bottle of 3 In 1 oil (or similar) to clean your tools after use. Should any spot of rust appear I keep a piece of 450 or 600 grit emery paper to hand, to rub out the offending spot. When preparing the rootstock it is a good idea to keep the anvil of the secateurs above the rootstock so that if any bruising occurs it will be on the piece which is discarded.
2 Rubber Bands. I use small 1¼ inch. Under the influence of light and water these rubber bands disintegrate very quickly possibly causing the graft to fail. Therefore it is a very good idea to use a second rubber band to reinforce the first. They are very inexpensive.
3 Poythene film squares. These are cut from small bags that our local pharmacies use for dispensing small quantities of medicines. They are approximately 9 inches by 5 inches and fabricated out of 10 micron material (i.e. 1/100 mm). For “V” grafting I cut in half and used to throw away the bottom half. But for this grafting I now cut each bag into 4 or use up the lower half of a “V” graft bag, which I just cut in two.
This material is a little like shrink wrap. It stretches but is not elastic. I put the scion onto the rootstock and carefully place one of these very flimsy squares of plastic bag centrally over the scion. Then using a small rubber band this is held in position and then the plastic is carefully stretched to hold the scion in position
One of our members expressed concern about the polarity of flat grafts. It is usually very easy to tell which way up the scion is – the “D” shaped bud should have the flat side uppermost. Also if you work from the top of the scion, the top of the last cut will blacken quite quickly giving you another clue as to which is the top and which is the bottom. However, it is not the end of the world if you do inadvertently place the graft upside down – see next photo.
If you are using a Lenox knife with a disposable blade I have found a useful modification is to apply a small label or shim between the blade and the body of the knife which keeps the blade absolutely rigid – and no wobble!
Now place the scion on the rootstock, I find it easiest with tweezers so I can position the scion exactly in the middle of the rootstock. Then with the other hand, take a square of the plastic film and place it centrally over the scion – then place a finger on top of this to hold it in place. This should all be done very quickly before any exudates appear in either the rootstock or scion. Now gently pull the film around the rootstock and then apply a single rubber band.
Now pull the plastic film below the rubber band – gently, to make a firm union between the scion and the rootstock. Then, finally apply a second rubber band. With light and humidity, I have found that around 10% of rubber bands will fail in the first week and cause the graft union to fail. This second rubber band will prevent this. The grafting is now complete, all you have to do now is to write a label and record your graft in your graft book.
I now place the grafts in full shade, after 10 days I cut the rubber bands off with scissors and remove the plastic film. As soon as the buds start to grow I place the grafts into a lightly shaded position for around two weeks and then they can go into full sun. They will start to flower after around three months.
This really is a very simple technique and I can recommend it to anyone who is manually dextrous.