Grafting and Budding Nursery Crop PlantsAG-396

Grafting

When to Graft   Unlike budding, which can be performed before or during the growing season, most grafting is done during winter and early spring while both scion and rootstock are still dormant. Containerized plants may be moved indoors during the actual grafting process; after grafting, these plants are placed in protected areas or in unheated overwintering houses. Field-grown stock, of course, must be grafted in place. Some deciduous trees are commonly grafted as bare rootstock during the winter and stored until spring planting. Indoor winter grafting is often referred to as bench grafting because it is accomplished at a bench.

Selecting and Handling Scion Wood   The best quality scion wood usually comes from shoots grown the previous

season. Scions should be severed with sharp, clean shears or knives and placed immediately in moistened burlap or plastic bags. It is good practice during the harvesting of scions and the making of grafts to clean the cutting tools regularly. This may be done by flaming or immersing them in a sterilizing solution. Isopropyl (rubbing) alcohol also works well as a sterilant, although it evaporates quite readily. An alternative sterilizing solution may be prepared by mixing one part household bleach with nine parts water (by volume). However, this bleach solution can be highly corrosive to certain metals.   For best results, harvest only as much scion wood as can be used for grafting during the same day. Select only healthy scion wood that is free from insect, disease, or winter damage. Be sure the stock plants are of good quality, healthy, and true to type. Scion wood that is frozen at harvest often knits more slowly and in lower percentage. If large quantities of scion wood must be harvested at one time, follow these steps:

Cut all scions to a uniform length, keep their basal ends together, and tie them in bundles of known quantity (for example, 50 scions per bundle).

Label them, recording the cultivar, date of harvest, and location of the stock plant.

Wrap the base of the bundles in moistened burlap or sphagnum, place them in polyethylene or waterproof paper bags, and seal the bags.

Store the bundles for short periods, if necessary, either iced down in insulated coolers or in a commercial storage unit at 32o to 34oF.

Never store scions in refrigerated units where fruits or vegetables are currently kept or have been stored recently. Stored fruits and vegetables release ethylene gas, which can cause woody plant buds to abort, making the scions useless.

Keep the scions from freezing during storage.

NOTE: In grafting, as well as budding, the vascular cambium of the scion or bud must be aligned with the vascular cambium of rootstock. In woody plants the cambium is a very thin ribbon of actively dividing cells located just below the bark. The cambium produces conductive tissue for the actively growing plant (Figure 1). This vascular cambium initiates callus tissue at the graft and bud unions in addition to stimulating tissue growth on the basal ends of many vegetative cuttings before they have rooted.

Figure 1. Cross section of a woody plant stem.

Types of Grafts   Nurserymen can choose from a number of different types of grafts. This section describes only those basic types of grafts used on nursery crop plants.

Cleft Graft   One of the simplest and most popular forms of grafting, cleft grafting (Figure 2), is a method for top working both flowering and fruiting trees (apples, cherries, pears, and peaches) in order to change varieties. Cleft grafting is also used to propagate varieties of camellias that are difficult to root. This type of grafting is usually done during the winter and early spring while both scion and rootstock are still dormant. Cleft grafting may be performed on main stems or on lateral or scaffold branches.   The rootstock used for cleft grafting should range from 1 to 4 inches in diameter and should be straight grained. The scion should be about 1/4 inch in diameter, straight, and long enough to have at least three buds. Scions that are between 6 and 8 inches long are usually the easiest to use.

Figure 2. Cleft graft.

   Preparing the Rootstock. The stock should be sawed off with a clean, smooth cut perpendicular to the main axis of the stem to be grafted. Using a clefting tool wedge and a mallet, make a split or "cleft" through the center of the stock and down 2 to 3 inches. Remove the clefting tool wedge and drive the pick end of the tool into the center of the newly made cleft so that the stock can be held open while inserting the scion.   Preparing the Scion. In cleft grafting, one scion is usually inserted at each end of the cleft, so prepare two scions for each graft. Select scions that have three or four good buds. Using a sharp, clean grafting knife, start near the base of the lowest bud and make two opposing smooth-tapered cuts 1 to 2 inches long toward the basal end of the scion. Cut the side with the lowest bud slightly thicker than the opposite side. Be sure the basal end of the scion gradually tapers off along both sides.   Inserting the Scion. Insert a scion on each end of the cleft, with the wider side of the wedge facing outward. The cambium of each scion should contact the cambium of the rootstock.   Securing the Graft. Remove the clefting tool from the cleft so that the rootstock can close. Pressure from the rootstock will hold the scions in place. Thoroughly seal all cut surfaces with grafting wax or grafting paint to keep out water and prevent drying. If both scions in the cleft "take," one will usually grow more rapidly than the other. After the first growing season, choose the stronger scion and prune out the weaker.

   NOTE: The temperature of grafting wax is critical. It must be hot enough to flow but not so hot as to kill plant tissue. Recently, paint-like sealants have replaced wax in many areas because they are easier to use and require no heating.

Bark Graft   Bark grafting (Figure 3) is used primarily to top work flowering and fruiting trees. In contrast to cleft grafting, this technique can be applied to rootstock of larger diameter (4 to 12 inches) and is done during early spring when the bark slips easily from the wood but before major sap flow. The rootstock is severed with a sharp saw, leaving a clean cut as with cleft grafting.

Figure 3. Bark graft.

   Preparing the Stock. Start at the cut surface of the rootstock and make a vertical slit through the bark where each scion can be inserted (2 inches long and spaced 1 inch apart).   Preparing the Scion. Since multiple scions are usually inserted around the cut surface of the rootstock, prepare several scions for each graft. Cut the base of each scion to a 1 ½- to 2-inch tapered wedge on one side only.   Inserting the Scion. Loosen the bark slightly and insert the scion so that the wedge-shaped tapered surface of the scion is against the exposed wood under the

flap of bark. Push the scion firmly down into place behind the flap of bark, replace the bark flap, and nail the scion in place by driving one or two wire brads through the bark and scion into the rootstock. Insert a scion every 3 to 4 inches around the cut perimeter of the rootstock.   Securing the Graft. Seal all exposed surfaces with grafting wax or grafting paint. Once the scions have begun to grow, leave only the most vigorous one on each stub; prune out all the others. Bark grafts tend to form weak unions and therefore usually require staking or support during the first few years.

Side-Veneer Graft   At one time the side-veneer graft (Figure 4) was a popular technique for grafting varieties of camellias and rhododendrons that are difficult to root. Currently, it is the most popular way to graft conifers, especially those having a compact or dwarf form. Side-veneer grafting is usually done on potted rootstock.

Figure 4. Side veneer graft

   Preparing the Stock. Rootstock is grown in pots the season before grafting, allowed to go dormant, and then stored as with other container nursery stock. After exposure to cold weather for at least six weeks, the rootstock is brought into a cool greenhouse for a few days before grafting takes place to encourage renewed root growth. The plant should not be watered at this time.   Make a shallow downward cut about 3/4 inch to 1 inch long at the base of the stem on the potted rootstock to expose a flap of bark with some wood still attached. Make an inward cut at the base so that the flap of bark and wood can be removed

from the rootstock.   Preparing the Scion. Choose a scion with a diameter the same as or slightly smaller than the rootstock. Make a sloping cut 3/4 to 1 inch long at the base of the scion. (Use the bark grafting technique shown in Figure 3.)   Inserting the Scion. Insert the cut surface of the scion against the cut surface of the rootstock. Be certain that the cambia contact each other.   Securing the Graft. Hold the scion in place using a rubber grafting strip, tape, or grafting twine. Seal the entire graft area with warm grafting wax or grafting paint. Remove the rubber or twine shortly after the union has healed. Never allow the binding material to girdle the stem.

Splice Graft   Splice grafting (Figure 5) is used to join a scion onto the stem of a rootstock or onto an intact rootpiece. This simple method is usually applied to herbaceous materials that callus or "knit" easily, or it is used on plants with a stem diameter of 1/2 inch or less. In splice grafting, both the stock and scion must be of the same diameter.

Figure 5. Splice graft.

   Preparing the Stock and Scion.Cut off the rootstock using a diagonal cut 3/4 to 1 inch long. Make the same type of cut at the base of the scion.   Inserting the Scion. Fit the scion to the stock. Wrap this junction securely with a rubber grafting strip or twine.   Securing the Graft. Seal the junction with grafting wax or grafting paint. Water rootstock sparingly until the graft knits. Over watering may cause sap to "drown" the scion. Be sure to remove the twine or strip as soon as the graft has healed.

Whip and Tongue Graft

   The whip and tongue technique (Figure 6) is most commonly used to graft nursery crops or woody ornamentals. Both the rootstock and scion should be of equal size and preferably no more than 1/2 inch in diameter. The technique is similar to splice grafting except that the whip on the rootstock holds the tongue of the scion in place (and vice versa). This leaves both hands free to wrap the joint.   For the whip and tongue graft, make similar cuts on both the stock and scion. These cuts should be made with a single draw of the knife and should have a smooth surface so that the two can develop a good graft union. Up to this point, rootstock and scion are cut the same as for a splice graft.

Figure 6. Whip and tongue graft.

   Preparing the Stock and Scion. Cut off the stock using a diagonal cut. The cut should be four to five times longer than the diameter of the stock to be grafted. Make the same kind of cut at the base of the scion.   Next, place the blade of the knife across the cut end of the stock, halfway between the bark and pith (on the upper part of the cut surface). Use a single knife stroke to draw the blade down at an angle through the wood and pith. Stop at the base of the initial diagonal cut. This second cut must not follow the grain of the wood but should run parallel to the first cut.   Inserting the Scion. Prepare the scion in the same way. Fit the scion into the rootstock so that they interlock whip and tongue. Be certain that the cambia are

aligned.   Securing the Graft. Wrap the junction with a grafting strip or twine, and seal it with grafting wax or grafting paint. Never allow the binding material to girdle the stem.

Saddle Graft   Saddle grafting (Figure 7) is a relatively easy technique to learn and once mastered can be performed quite rapidly. The stock may be either field-grown or potted. Both rootstock and scion should be the same diameter. For best results, use saddle grafting on dormant stock in mid- to late winter. Stock should not be more than 1 inch in diameter.

Figure 7. Saddle graft.

   Preparing the Stock. Using two opposing upward strokes of the grafting knife, sever the top from the rootstock. The resulting cut should resemble an inverted V, with the surface of the cuts ranging from 1/2 to 1 inch long.   Preparing the Scion. Now reverse the technique to prepare the base of the scion. These cuts on the rootstock and scion must be the same length and have the same slope so that a maximum amount of cambial tissue will make contact when the two halves are joined.   Inserting the Scion. Place the V-notched scion onto the saddle of the rootstock. If rootstock and scion are the same diameter, cambial alignment is easier; otherwise adjust as needed.   Securing the Graft. Wrap the graft with a grafting twine, tape, or strip, then seal it with grafting wax or grafting paint.

   All of the preceding techniques are used to top work horticultural crops for a particular purpose. Occasionally, however, grafting is used to repair injured or diseased plants. Two common techniques available for this purpose are bridge grafting and inarch grafting.

Bridge Graft   Bridge grafting (Figure 8) is used to "bridge" a diseased or damaged area of a plant, usually at or near the base of the trunk. Such damage commonly results from contact with grading or lawn maintenance equipment, or it may be caused by rodents, cold temperatures, or disease organisms. The bridge graft provides support as well as a pipeline that allows water and nutrients to move across the damaged area.   Bridge grafts are usually done in early spring just before active plant growth begins. They may be performed any time the bark on the injured plant "slips."

Figure 8. Bridge graft.

   Preparing the Scion. Select scions that are straight and about twice as long as the damaged area to be bridged. Make a 1 1/2- to 2-inch-long tapered cut on the same plane at each end of the scion.   Preparing the Stock. Remove any damaged tissue so the graft is on healthy stems. Cut a flap in the bark on the rootstock the same width as the scion and below the injury to be repaired. Gently fold the flap away from the stock, being careful not to tear the bark flap.   Inserting the Scion. First, insert and secure the scion below the injury; push the scion under the flap with the cut portion of the scion against the wood of the injured stem or trunk. Then go back and insert and secure the scion above the injury following these same steps. Push the scion firmly into place. Pull the flap over the scion and tack it into place as described for bark grafting (Figure 3).   When grafting with young stems that may waver in the wind, insert the scions so that they bow outward slightly. Bridge grafts should be spaced about 3 to 4 inches apart across the damaged area.   Securing the Graft. Secure all graft areas with warm grafting wax or grafting

paint. During and after the healing period, remove any buds or shoots that develop on the scions.

Inarch Graft

   Inarching, like bridge grafting, is used to bypass or support a damaged or weakened area of a plant stem (Figure 9). Unlike bridge grafting, the scion can be an existing shoot, sucker, or watersprout that is already growing below and extending above the injury. The scion may also be a shoot of the same species as the injured plant growing on its own root system next to the main trunk of the damaged tree. With the inarching technique, the tip of the scion is grafted in above the injury using the same method as for bark or bridge grafting.

Figure 9. Inarch graft.

Grafting, Pruning and CompostingPosted on May 1, 2011 by barbaramatthews

     Friday afternoon our class had a hands-on workshop.  We split off into three groups, and visited grafting,

pruning, and compost stations.  I had previously done some pruning and composting (although I didn’t really

know the technicalities of either), but had zero experience with grafting.

     My first stop was the grafting station.  I learned that grafting is the fusing of one plant’s tissues with

another.  One plant is chosen for its roots, and is referred to as the

 root stock, while the other is selected for its stems, leaves,

flowers, or fruits–it is refered to as the scion.   *It can take 5 t0 15 years (depending on the species) for a tree

to mature and produce fruits, but a scion fused with a mature root stock will fruit in as little as two years; this

is one of the greatest benefits of grafting.

     We practiced grafting with the stem of a pear tree; we cut the stem (scion) in half and pretended that one

part was a root stock.  The key to successful grafting is notching the root stem, and slicing the scion in such a

way that they fit together like a puzzle piece–theirvascular cambium tissues in full contact with one

another.  (This is the green edge  found upon cutting into the wood).  The point at which the scion and root

stock are connected is then wrapped in special grafting tape; this will hold them togethe

r until the tissues have merged.

      My group’s second stop was the  pruning station, where we worked on a pear tree.  We learned that the

main reason for pruning is to  increase fruit yield and ensure the health of the tree. To do this, examine

the strongest of the branches in the middle of the tree, and choose one to be thecentral leader; this

branch’s orientation will determine which other branches and stems are pruned.   *The central leader should

receive as much direct sunlight as possible.  Any branch or stem which is shading or crossing the central

leader should be removed.  *Keeping the tree pruned will concentrate nutrients, ensuring quality fruits.

     Our last stop was the composting station.  We learned that compost is made up of four elements:  nitrogen,

carbon, water, and air.  For nitrogen, add layers of green plants and manure; for carbon add layers

of brown/woody materials–such as leaves, straw and mulch.  Keep adding layers–each hosed down with water–

until you have a pile of compost that is at least 3×3 foot.   Leave the pile sitting for four days and then flip it,

so that the bottom layer becomes the top. *Do this to ensure the compost stays aerated.  Also flip on days 7,

11, and 18.  After day 18, the compost will be ready for use as a fertilizer and soil amendment.

     I had a great time doing this workshop; especially the grafting aspect.  I prefer fresh air and sunshine to a

classroom any day.  Also, I find that working hands-on with a subject  helps me to better understand and

absorb the information being presented; it’s an excellent approach to education.

Otherwise known as 'top working' or 'grafting over', this is a technique for converting an apple tree which is growing OK in the right place but whose fruit is unacceptable for some reason and you want to replace it with a different variety. This is much better than digging out the tree and replacing it with a new one and is used commercially. As mentioned elsewhere, I have done this a few times over

the past few years, once when I realised that Spartan was very prone to scab and also did not sell well-I grafted over 40 trees to Suntan and Ashmead's Kernel (I have not regretted this one bit) and in the spring of 2007 when I grafted over 8 cider apple Crimson King (not to be confused with the 70s prog rock band King Crimson) to 4 each of Harry Masters' Jersey and Dabinett, as the latter 2 varieties proved to be far better on our land. So far these are growing OK and the pictures in this page are taken from this example. The picture immediately below shows a tree after top working, in April. Note that it has been cut back severely and several polythene ties can be seen, see below for close ups and explanations.

Top working can employ more than one grafting style. In this case, I used saddle grafts, cleft grafts, rind grafts and stab grafts. Like many things in life, if you get an understanding for the basic techniques and underlying principles, you can improvise and get away with it much of the time. Life could hardly go on otherwise. I am always amazed when any graft takes successfully, however many

times I see it happen. The tree in the picture below shows 4 kinds of graft. From left to right, double rind raft, saddle graft, double cleft graft (right upper) and single rind graft (right lower). The different techniques suit different diameters of wood and angles better, th more techniques you are competent with , the more versatile you can be. NOTE the saddle graft is coming right at you in the photo and is much thinner than it appears due to perspective. They all took well, some even tried to set fruit!

As with all forms of grafting, cut clean straight growths of last years wood LABEL THEM, wrap in polythene and store in the fridge (not freezer. take care if like us your fridge freezes up in places.) If you are short of fridge space, a damp sack in a cool dark place will do. Keep it damp. Cut this wood before any sign of green appears, February to early March is best. You then graft ONTO A GROWING TREE once spring starts. Others will say graft in the dormant season, I only teach what I know and what I do. You decide, but since I started grafting dormant stored scion wood onto actively growing rootstock, usually in April, I have had the highest success rates ever, close to 90%.

The picture below is a double rind graft, picture taken a few weeks after grafting, you can see leaves coming from the end on one of the scion pencils. The next picture shows the same or an identical graft 2 months later. To do the rind graft, saw across, slit the bark, then slip your taper cut scion down and tie firmly (described more fully below). Seal with wax, making sure wax doesn't get between live wood surfaces you are hoping to graft.

This double rind graft has now taken beautifully, you can see shoots coming out as well as abundant leaf. The great thing about top working is that you are beginning with a strong root, trunk and main branch system, so there is a huge amount of natural energy to force up growth. This is why you can go from zero to full fruiting in 3 years, FAR better than digging out and replanting, although even that is preferable to putting up with an apple variety which is wrong for you. The pictures above were taken shortly after grafting in April 2007, the pictures BELOW are the same trees in July the same year. you can see the grafts have taken and grown well, there were only a few failures, and most of those were due to birds perching on the fragile new branches and snapping them off. We have never asked for or received a penny of agricultural subsidy, but I think it is justified to compensate farmers and growers for the economic loss caused by these pretty animals which the law prevents us from taking action against. Not that I would bake blackbirds, let alone rooks, in a pie. Well only a few now and then, but it is frustrating to see the damage birds do especially since we have planted half a mile of hedgerow and 2 acres of coppice which benefit them enormously.

RIND GRAFT

Rind grafting was accomplished using 2 tools, the Silky Fox saw (I use no other) to saw the branch off, and the Opinel number 6 stainless steel penknife, sharpened and sterilised. Saw across, make a 3cm slit down the bark, then sharpen a piece if scion wood into a wedge and slide it down between rind and the underlying wood. Make a perfect fit, then do the same on the other side, squeeze a bit of soft grafting wax to seal the loose edge of the rind, and secure with tape. The picture shows the result, on the left you can see the free edge of rind which has callused over. (callus is temporary healing tissue, something very similar is produced when human or animal bones are healing after a break, a sort of auto-graft scaffolding/glue)

here's a picture of the same union from a different angle, showing on the right a free growing shoot arising from the rootstock. we do not want this, and it is vital to cut it off as (a) it is of the variety you don't want and are replacing., and (b) it will compete with the chosen new variety. Cut it out, the sooner the better

(should have been done before now, too busy).

Here is a successful CLEFT graft, on a thinner diameter branch. This involves, after sawing the branch across, using a heavier knife to split it down the middle, HORIZONTALLY where the branch is other than entirely upright(this is important, vertically cut clefts fail much more often) then cutting 2 scion pencils to wedge shapes, with a square butt, and fitting them into the cleft so they are wedged firmly. This can be a very easy graft to perform. NOTE the thin sliver of scion wood trapped firmly between the 2 sides of the split (clefted) rootstock branch. This technique leaves a gap in the middle between the 2 scions (always do 2), fill this up with grafting wax. Again, this is a double graft, usually employed in these cases to avoid asymmetry. With a very big diameter stock (best avoided but sometimes inevitable) I will sometimes graft 3 or 4 pencils in.

CLEFT GRAFT AGAIN, SMALLER DIAMETER STOCK The technique you use depends to a large extent on the diameter, and particularly on the difference in diameter between rootstock and scion. You can't do cleft grafts on to really big diameter stocks, the above is about the upper limit, as it leaves too big a gap in between which can be an entry point for diseases and insects-smaller gaps will seal themselves. Below is another example of the cleft graft using a very thin diameter, about the thinnest you could use.The honey coloured stuff above the join is grafting wax, you have to look twice to see that there are 2 scions in this picture, they have swelled up somewhat since grafting was performed/ you can see the thin tapering wedge to the left of the midline below the join with healthy callus either side. The straight slit in the wood to the right of the midline was made by the sharp knife I used to release the polythene tie, ideally I would not have made this cut but it is unlikely to do any harm. The pressure of the sap inside the actively growing wood has caused it to open a millimetre

Saddle grafting (dealt with elsewhere) is useful where the stock and scion wood are nearly or exactly the same diameter. This is my favourite graft whenever possible and I use it exclusively for grafting onto new young stocks in the nursery. This technique requires stock and scion to be similar diameters (you can push the limits if yous skill improves) and basically means cutting a sloping V shaped 'male' wedge in the stock, a corresponding V shaped 'female' shape in the scion, marrying the 2 together and whipping with polythene tape. Looks a bit like this

====>>====

The flexibility of the thinly cut live wood means you can almost always get very good cambium to cambium contact (the cambium being the live growing wet area under the bark) and this sort almost always takes successfully once you nave got the basic hang of it.

this looks a bit wonky as the polythene has just come off, and may have been applied a bit too tight, but should do well. I will add some pictures of mature grafts later.

Sometimes you want a new branch to some out of a main trunk, difficult. It can be

done by the stab graft, which consists of a scion cut to shape and inserted through a cut made in the main body of the tree. This is an occasional graft and not recommended as it fails more than some other sorts and may let disease into the tree.

STAB GRAFT

This was growing away well. The technique here was to raise an oblong flap, slide the tapered scion down tightly, making good smooth cambium to cambium contact, wax and tie firmly with polythenne tape to hold the live edges together as they grow into each other. Some old books say nail it down with a fine pin, I haven't tried this.

There are other techniques, the saddle and cleft are the ones I use most although the rind is also very helpful at times. I recently used the techiniques of top working to convert an unwanted and very badly trained Bramley over to a Baker's Delicious, a rare and very tasty early dessert apple, and I am glad to say it was entirely successful with fruit in the second year. Another time, when we were planting out the Cobbett's orchard, we realised we needed more trees of Winter King as they were so popular with customers and had an excellent shelf life. I had plenty of oversized surplus to requirements MM106 rootstocks which were going to be thrown out, so I planted them in a row 33 in all, and cleft grafted every one with Winter King. I am glad to say I had 100% take and those trees are carrying a

very heavy crop today (14th July 2007).

Every orchardist should consider learning how to graft, for economy, to help others (save your friend or neighbour a sample of that lovely old tree in the house they have to leave)and for fun. You can always try the first time in a low-risk situation by just trying to saddle graft a few pencils of a different variety into an established tree, this can be useful for pollination-another benefit of the technique.