Can Grafted Trees Revert To Their Rootstock?


By: Nikki Tilley, Author of The Bulb-o-licious Garden

Tree grafting is an excellent way to bring the best of two varieties together into a single tree. Grafting trees is a practice that has been done by farmers and gardeners for hundreds of years, but the method is not fool proof. Sometimes grafted trees can revert to their original form.

How Does Tree Grafting Work?

Grafting trees begin with healthy rootstock, which should be at least a few years old with a firm, straight trunk. You must then find another tree, which can bear the fruit, referred to as the scion. Scions are usually second year wood with good leaf buds and about ¼ to ½ inch (0.6 to 1.27 cm.) in diameter. It is important that this tree be closely related to the rootstock tree.

After cutting a branch from the scion (diagonally), it is then placed into a shallow cut within the rootstock’s trunk. This is then binded together with tape or string. From this point on you wait until the two trees have grown together, with the scion branch now a branch of the rootstock.

At this time all the top growth (from rootstock) above the graft is removed so that the grafted branch (scion) becomes the new trunk. This process produces a tree that has same genetics of the scion but the root system of the rootstock.

Rootstock Revert: Trees Grafted Return to the Original

Sometimes grafted rootstocks can sucker and send out shoots that revert to the type of growth of the original tree. If these suckers are not cut off and removed, it can overtake the growth of the graft.

The best way to prevent the rootstock from taking over is to remove any new sucker growth that appears below the graft line. If the graft line goes below the ground, the tree may revert to its rootstock through suckers and give the wrong fruit.

There are various reasons for a reversion in trees grafted. For instance, grafted trees respond to severe pruning by sprouting from below the graft and reverting back to the rootstock.

Rejection of the grafted scion (original grafting tree branches) can also occur. Rejection often occurs when grafted trees are not similar. They (rootstock and scion) must be closely related in order for the graft to take.

Sometimes scion branches on grafted trees simply die, and the rootstock is free to regrow.

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Understanding Grafted Ornamental Trees

Today's garden centers are filled with a fascinating and beautiful array of ornamental trees that have been manipulated to weep, or curl, or do other things that, in their natural state, they would not. In early spring, neighborhoods filled with weeping cherry and ornamental crab-apple trees provide a breathtaking display of spring beauty. Understanding the process of grafting and the problems it can produce are key to using these specimens in the landscape.

Ornamental fruit trees are not the only species for which a weeping habit has been cultivated, but these flowering trees are among the most popular for home landscapes. The weeping cherry at right is quite magnificent, but has clearly outgrown the small space originally allocated when it was a sapling. So this is one of the problems to consider when purchasing an ornamental tree. Other common problems associated with grafted trees include water sprouts, suckers, and diseases. The process of grafting is such that one or two areas of the plant are stressed in the beginning, with the potential of reducing the vigor of the plant.

How Is Grafting Done?

A single graft is the process of merging a less hardy species onto very hardy rootstock. For instance, a weeping crabapple cultivar would be grafted to standard crabapple rootstock, making the resulting tree better able to withstand the elements. This is done by aligning the cambium layers so they will grow together.

A double graft uses the same technique of combining hardy rootstock and hardy main trunk stock called the interstem graft, but takes the process one step further by grafting the desired cultivar to the top of the trunk. This top portion of the tree is known as the scion and is the only part of the tree that will produce the desired leaves, flowers, and/or fruit. The interstem and rootstock will regulate the mature size of the tree. Grafted trees can fail within the first few years of life, particularly as a result of severe weather stress. The key to assuring that you buy a healthy tree is purchasing from reputable nurseries and garden centers that provide at least a one-year guarantee. Discuss with the grower what type of graft has been done, and understand the mature size of the tree, as well as its care.


Water Sprouts
Epicormic branches are known as water sprouts and are easily recognized on a weeping variety. Water sprouts grow straight up, and they grow quickly, sometimes reaching 3 to 4 feet long in a single season. These branches will not flower or produce fruit, but will sap energy from the tree. They should be pruned close to the collar as soon as they begin to appear.


Suckers
Suckers grow from the rootstock of the tree and, again, sap energy from the plant. Suckers are hard to control, but the main reason for the problem is an improper planting depth at the time the tree is situated. The graft union must be above ground in order to prevent the growth of suckers. If the tree is already planted, when suckers begin to appear, clear away the soil from around the base of the tree and prune the suckers as close to their source as possible. Replace the soil. This will not p revent more suckers from growing, but if done frequently, they will not affect the vigor of the tree.

Disease
As with the wound caused by a broken branch or limb, the wound of grafting is susceptible to disease and insect invasion. Before purchasing, check the graft union carefully to be sure there are no cracks or irregular growth. Cherry and plum are particularly prone to disease at any wound or weak crotch. Large globs of amber-looking material will ooze from the wound or beneath the bark, eventually turning black. Consult your nursery for advice on how to manage this situation.


Location
As mentioned before, be sure you know the mature size of the tree you are considering. If a weeping cultivar has been grafted to the interstem of a full-size tree, you will not be able to contain the tree as it matures. Again, know what you are buying.

Coniferous
Needle juniper (Juniperus rigida)
Tolleson's weeping juniper (Juniperus scopulorum 'Tolleson's Weeping')
Weeping Eastern red cedar (Juniperus virginiana 'Pendula')
Weeping Alaska cedar (Chamaecyparis nootkatensis 'Pendula')
Weeping Serbian spruce (Picea omorika 'Pendula')
Weeping white spruce (Picea glauca 'Pendula')

Deciduous
'Chaparral' weeping mulberry (Morus alba 'Chaparral')
'Louisa' weeping crabapple (Malus x 'Louisa')
Golden weeping willow (Salix alba 'Tristis')
Weeping Eastern white pine (Pinus strobus 'Pendula')
Weeping European beech (Fagus sylvatica 'Pendula') and (Fagus sylvatica 'Purple Foundtain')
Weeping European larch (Larix decidua 'Pendula')
Weeping Higan cherry (Prunus subhirtella 'Pendula')
Weeping katsura (Cercidiphyllum japonicum 'Pendulum')
Weeping Norway spruce (Picea abies 'Inversa')

1 "Bring grace to the landscape with weeping trees", http://www.grounds-mag.com

About Toni Leland

About Toni Leland

Toni Leland has been writing for over 20 years. As a spokesman for the Ohio State University Master Gardener program, she has written a biweekly newspaper column and is the editor of the Muskingum County MG newsletter, Connections she currently writes for GRIT, Over the Back Fence, and Country Living magazines. She has been a gardener all her life, working soil all over the world. In her day job, she scripts and produces educational DVDs about caring for Miniature Horses, writes and edits books about them, and has published five novels.


What Is a Rootstock?

The lower plant portion used in grafting is called the rootstock. This is usually a healthy root system and some portion of the stem. You've probably seen a nubby bump at the base of rose bushes or fruit trees, like the one in the photo. This is where the graft was made the graft union. Everything below the bump is rootstock.

The characteristics of rootstocks can make it possible to grow plants faster and in less than desirable conditions. One of the most common uses for rootstocks is creating dwarf fruit trees. Most fruit trees are not only too large for the average backyard they also take years to mature to a size that is capable of bearing fruit. By grafting a favorite fruit tree onto a rootstock that produces dwarf trees, we are able to create a tree as short as only 6 ft. tall. This is an easy height for a gardener to maintain and pick from and it helps the commercial orchards get up and producing sooner.

Besides dwarfing, rootstocks can contribute traits to improve yield, cold or drought hardiness, and even disease resistance. Many European wine grapes are grown on a North American rootstock that was discovered to have a resistance to phylloxera, an insect that was threatening the vines in the 19th century.


How Grafting Works

To create a grafted plant, you need a shoot and a root.

The shoot is called a scion. This is a mature (but not too old) branch or stem that can produce flowers and fruit.

The base is the rootstock.

The two are bound together in such a way to allow the exchange of water and nutrients, with direct contact between their cambium regions. It’s a living union.

Depending on the method, this may involve inserting a scion or bud into a stem, branch, or root area of the rootstock.

Techniques include cleft, side, bridge, veneer, and whip or tongue grafting.

But, before you start experimenting, keep in mind that it’s a fairly narrow range of scions and rootstocks that can be successfully grafted together.

Plants from the same species are nearly always compatible. This doesn’t mean they always work it just means it is biologically possible.

Different species in the same genus will usually work, but not always. A viable example includes tomatoes and potatoes which are both from the Solanum genus.

In the Video section below, there is a tree with 40 varieties of stone fruits growing on one rootstock.

Moving up the biological classification chart, plants from different genera but within the same family are usually not compatible and plants from different families can almost never be grafted successfully.

That said, grafting success is not strictly yes or no even within known compatible pieces: there are degrees of compatibility and it can take years to determine whether a particular combination will work. Disease and stressors can also interfere.

To avoid disappointment, find an expert or trusted resource guide to ensure you are starting with the right plants at the right time using the optimum method.


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two pear varieties grafted onto the same rootstock

No one knows when grafting of plants began. Initially, grafting was thought to be an extension of vegetative or clonal propagation by cuttings. Just as softwood (shoot) or hardwood cuttings, detached from certain plants and placed directly into the ground at the proper time of the year, will strike roots and grow into new plants, it was thought that grafting was a similar process. The only difference was that, in grafting, the detached shoot from one plant would supposedly “take root” in the stem or the trunk of another.

Bud grafting of citrus fruit tree

Today, most fruit trees are produced by bud grafting, known in the nursery trade as just plain “budding.” A bud growing on a tree that you wish to clone is grafted into a pencil-sized stem of what is typically a seedling of the same species or of a different, but related, species. The reason for doing this is that the scion will exhibit more vigor when grafted into a rootstock seedling that if it were cloned, for example, as a cutting and grown on its own roots. Today it is possible to grow Santa Rosa plum, Elberta peach, Bing cherry, and Gala apple trees from clonal cuttings but the trees that result are much less healthy than when buds of these trees are grafted onto rootstocks. Grafted trees have increased quantity, and sometimes even better quality, of fruit, disease resistance, pest and nematode (a microscopic, soil-dwelling worm-like organism) resistance, and cold tolerance.


Question of the Month: Grafting

Question: It seems like a lot of things are being grafted these days. Why is this, and should I really care?

—Shirley Cameron, Suquamish, Washington

Bert Cregg, an associate professor of horticulture and forestry at Michigan State University

EXPERT 1 ANSWER: Bert Cregg

There are several reasons why landscape plants are grafted and several reasons why you should care. Plants can be grafted using several different techniques, but all involve combining the top part (scion) of one plant with the bottom part of another plant (usually called a rootstock or understock). The principle reason for grafting is to maintain uniformity and consistency in specific desired traits. For landscape plants, this usually means ornamental characteristics, such as form (think weeping or columnar trees), flowers, or leaf color. For tree fruits, like apples, scions are selected for their particular fruit variety.

Another reason plants are grafted is because of the desirability of particular rootstocks. The most common examples of this are dwarfing rootstocks used for many fruit trees and some ornamentals.

So why should you care whether or not plants are grafted? First is the issue of uniformity. If you plant six red maple trees (Acer rubrum, USDA Hardiness Zones 4–9) on both sides of your driveway and you want them to grow at a similar rate and have uniform fall color, then you want to select a named cultivar, virtually all of which are grafted. If you were to plant seedling (nongrafted) red maples, you might end up with six trees that have different growth rates or that vary in intensity and duration of fall color.

Second, there are some negative consequences of grafting that you need to be aware of. During the process of grafting, the vascular tissue of the scion must fuse with that of the understock. Nurseries that specialize in propagation have grafting down to a science and have high success rates. Sometimes, however, delayed graft incompatibility might occur, and the portion of the plant above the graft union might begin to decline or fail. As grafted plants age, you’ll sometimes see increasing differences in growth rate between the top portion of the plant and the understock. This can ultimately lead to a weak point at the graft union, which can result in breakage. Last, knowing whether or not a plant is grafted can be important if something severe—such as winter dieback—should kill the scion but not the rootstock. In this case, the rootstock might send up suckers that are different from the original plant, leading to Extension hotline calls, such as, “Why is my yellow rose bush now producing red roses?!”

Douglas Justice, associate director and curator of collections at the University of British Columbia Botanical Garden

EXPERT #2 ANSWER: Douglas Justice

Grafting is a common nursery technique used for a variety of horticultural applications. Culinary apples, for example, are typically grafted on rootstocks that confer size control. The vast majority of apple trees are now grown on dwarf or semidwarf rootstocks so that the trees can fit small gardens and restricted spaces. Many landscape plants can, of course, be propagated by seed, but where plants need to be true to the cultivar, some kind of vegetative propagation is normally required. Taking stem cuttings would seem like the obvious (and easy) choice, but some plants do not easily make roots from cuttings. Take redbud (Cercis canadensis, Zones 5–9), for example. The species is famously difficult to root or at least to survive once rooted, so it is generally grafted—or, technically, budded (budding is a kind of grafting).

Large-leaved plants, such as magnolias (Magnolia spp. and cvs., Zones 5–9), though mostly rootable, are sometimes too unwieldy to be comfortably raised in a propagating frame. It’s often just faster and cheaper to produce a salable plant by grafting it onto an inexpensive seedling rootstock. This is certainly the case with cultivars of Japanese maple (Acer palmatum, Zones 5–9). Many maples can be successfully rooted on their own, but rooting percentages and overwintering survival are often low without the use of sophisticated environmental controls and the existence of considerable management expertise. In most cases, grafting is the less expensive option, and the plants tend to grow faster and mature sooner anyway. So grafting is a logical choice, especially for small nurseries.

But back to your question, “Should I care?” The answer depends on what is being grafted. Hybrid witch hazel (Hamamelis X intermedia and cvs., Zones 4–8), for example, is routinely grafted onto seedlings of American witch hazel (H. virginiana, Zones 4–8), and these rootstocks are notorious for suckering, particularly if the graft is not a perfect one. The same goes for contorted hazel (Corylus avellana ‘Contorta’, Zones 5–9), which is typically grafted on straight hazel (C. avellana, Zones 5–9), a naturally suckering tree. In these examples, it’s mostly easy (albeit labor intensive) to recognize the scion (top) from the rootstock, so any offending suckers can be removed. On the other hand, cultivars of ginkgo (Ginkgo biloba, Zones 4–9) are sometimes grafted onto ginkgo seedlings, which can be either male or female (it’s the luck of the draw what sex you’ll get, and distinguishing a male from a female is almost impossible). A female ginkgo produces seeds that are infamous for the rancid butter smell they give off once ripe. Because it often takes more than a decade for a ginkgo to become reproductively mature, that’s a long time to wait for what is potentially a very smelly surprise. So, yes, you should care—particularly when it comes to certain species, like ginkgo, because you might want to avoid grafted options altogether.


Grafting Tree Fruits and Its Benefits

Grafting Tree Fruits and Some Of Its Benefits

It can be difficult for farmers to earn their livelihoods from growing only grain crops. That’s why it’s good to learn new methods which increase production to farm our own land. One method is by making a nursery to grow improved fruit tree seedlings. This means you can grow tasty and nutritious fruit on your own land, and at the same time sell or trade extra production to earn cash. There are many methods of joining local wild fruit tree rootstock to high producing improved varieties. One of those methods, is called grafting. Grafting is a method of joining the cutting (scion) of an improved variety of fruit tree onto the root (rootstock) of a local compatible variety.

Many garden plants that we love and grow are actually made up of two different plants that have been skilfully joined together by the grower. This grafting has overcome many a propagation problem but it has also given us the opportunity to grow a far greater range of plants in our gardens. This is the benefit of grafted fruit trees to the nurseryman and also to the gardener.

You see, it is all very well finding a new variety as a side shoot of a plant but, if that little piece will not grow roots as a cutting, then the opportunity to propagate it and make it more widely available will be lost. You might think that the answer is to wait for that desirable piece of the plant to produce seeds. Sadly, few plants will be exactly the same when raised from seed and will have reverted to the original unimproved mother plant or will have hybridized into something quite random!

So for hundreds of years, both gardeners and nurserymen have been practicing the age old technique of taking a little piece of a plant and very skillfully attaching it to another so that it grows as one plant. The root part of the plant is called a ‘root stock’ and the little piece that is attached to it is the ‘scion’.

The kind of plants that we take for granted that are regularly grafted include flowers, virtually all fruit trees, many ornamental garden and street trees and a fair few of the most desirable garden shrubs!

The Benefits of grafting

  • Grafted trees produce fruit quicker. A tree grown from seed may take 8-10 years to fruit, but a grafted tree will only take 2-4 years.
  • A tree grown from seed may produce poor tasting fruit. Grafting is done to improve the taste and size of the fruit.
  • A tree grown from seed may not produce fruit the same as the tree the seed came from (mother tree). But a grafted tree will be just as good as the tree the cutting (scion) came from.
  • A grafted tree will continue to give the same quality fruit for many years.
  • Grafted fruit trees can be sold to give an income to the household.
  • By producing your own seedlings and fruit, you save money.
  • Seedlings can be produced locally, saving time in searching for the right fruit trees to plant
  • Some trees end up developing more resistance to diseases and adverse conditions than other trees. This disease resistance and hardiness is transferred from the rootstock (the plant being grafted onto) to the scion (the plant being propagated).

Below are some of the grafted fruit trees that we have. If in need, kindly contact us and we will deliver.


Watch the video: The BEST 11 Avocado Grafting Methods


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