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If I were to graft two apple saplings together -- by bending the tops toward each other and lashing them together -- will the plants grow as one and benefit from one another, or will they be fighting each other for root space and light? If they would grow with each other, then I could theoretically grow a line of closely spaced fruit trees to any length, and they would be strengthened by each other in bad conditions.
There are a couple of answers to this question. Especially where trees are concerned, you can graft two or more trees onto the same rootstock, or even a single limb into a tree.
But if the graft takes, it won't behave too much more differently than just more branches of the same tree. Structurally intertwining them will not be different than if you had just taken a single tree's branches to support each other. The graft will usually only have a single set of roots, from the host tree. They will not compete. The tendency will be for the branches to grow apart so that they can independently get their own light. This is very much like any other single tree. Not sure about fusing two halves of a tree together - exposing the roots would tend to kill the tree or unsettle it.
What you describe is not grafting it is called inosculation and can prodice some truly impressive results. Inosculation can sometimes lead to natural grafting but it just as often does not. Apples are a good candidate for this to form grafting but it is not guaranteed. More importantly said trees are often competing for light so you end up having to plant more trees for the same amount of fruit, plus it is extremely time consuming.
As for strengthening that depends a lot on what you call strengthening, they may help each other structurally but joining becomes a liability for say something like drought conditions because you have a smaller root mass per tree.
Many persimmon trees are propagated asexually by grafting. Grafting is a propagation method that allows you to meld two trees into one new specimen by joining a root system of one tree, termed the rootstock, to a shoot system from another tree, termed the scion. For example, you can select a rootstock from a hardy, tolerant or disease-resistant cultivar and the scion from a persimmon cultivar with abundant and delicious fruit. Generally, the preferred persimmon rootstocks come from Diospyros kaki or lotus. Popular scions include astringent varieties like Hachiya, with fruit that must ripen to mushy before eating, and nonastringent varieties like Fuyu, eaten as crisp as apples.
It is best to graft your persimmon during winter, when both the scion's parent tree and the young rootstock tree are dormant. You should select a rootstock tree with a stem at least three-eighths inch in diameter and take a scion cutting of about the same diameter. The scion must be 6 to 8 inches long and have two to four buds. In order to get the two different trees to grow together, the rootstock and the scion must be joined in such a way that the cambium tissues of their inner bark are touching each other.
Growing Fruit: Grafting Fruit Trees in the Home Orchard [fact sheet]
Grafting as a means of propagating fruit trees dates back several thousand years or more. Grafting is used for two principal reasons: most fruit trees don’t come true to seed (seeds from a McIntosh apple won’t grow into McIntosh trees) and cuttings don’t root easily. The technique of grafting is used to join a piece of vegetative wood (the scion) from a tree we wish to propagate to a rootstock.
Grafting is a fun way to get more enjoyment from your home orchard. You can use grafting to create trees with several varieties or to introduce new varieties into your home orchard. Grafting can also be used to change varieties of trees in your existing orchard (see Cleft Grafting, below).
Remember that you are almost always limited to grafting within a species. most apple varieties are compatible with each other as are most pears. You cannot graft an apple scion on a pear rootstock or vice versa.
Choice of rootstock
Today we have a wide range of rootstock choices that will produce trees of varying sizes, from full-size “standard” trees to true dwarfs (less than 10 feet tall at maturity). Different rootstocks vary not only in final tree size, but also in their winter hardiness, resistance to certain insects and diseases, and performance in various soil drainage types. Most dwarf rootstocks are also precocious, meaning that they bear fruit early in the tree’s life.
Rootstocks are propagated either by seed (for seedling rootstocks), or by the process of rooting cuttings, known as layering. Dwarfing rootstocks are usually rooted cuttings (Fig. 1). Several nurseries offer rootstocks in small quantities to home growers interested in grafting, and many nurseries offer fruit trees on a wide selection of rootstocks. Descriptions of some of the common apple rootstocks follow.
Seedling: Seedling rootstocks produce large trees that are very difficult to prune, harvest and manage for pests. Seedling rootstocks are not recommended for use in home gardens. Few home gardens have space for these large trees and the wait until first fruit will discourage most growers. In addition, pest control with these large trees is very difficult, usually requiring power equipment for spray application. However, these trees may have value when used for wildlife plantings. They cost less than trees with dwarfing rootstock and will grow rapidly, soon outgrowing the browse reach of deer if provided protection for just a few years
M.7 (Malling 7): M.7 was the dominant dwarfing rootstock in NH orchards for many years. It produces a semi-dwarf tree that reaches 15 feet in height and needs 15 feet of lateral space. Fruiting usually begins by the fifth year from planting. M.7 has some weaknesses, for example, it produces numerous root suckers that must be cut each year. On the positive side, M.7 is tolerant of collar rot, a major soil-borne disease of apple. Further, most varieties grafted on M.7 are very fruitful. Apple trees on M.7 should be staked to provide trunk support for the first four or five years.
M.26 (Malling 26): M.26 is an excellent apple rootstock for home gardens. It is precocious, often bearing some fruit as early as the year after planting. It is quite hardy and should do well in reasonably well-drained soils throughout NH. It produces very few root suckers. It needs support (preferably a stake that will last the life of the tree), and it produces fleshy root initials (called burr knots) on the above-ground portion of the rootstock. These burr knots are attractive to borers. M.26 is also susceptible to the bacterial disease fire blight. Plant the tree with the graft union only an inch or so above ground so less rootstock is exposed. Most varieties on M.26 can be planted at an 8-foot spacing.
Bud 9 (Budagovsky 9): This is the number one choice for NH home gardens if a fully dwarf tree is desired. This rootstock is productive, very precocious and when mature, trees on this rootstock stand only seven to eight feet tall. It should be staked to provide support for heavy crop loads. It is very hardy and should do well throughout NH. Apple trees on Bud 9 rootstock can be set at 7-foot spacing in the home orchard.
Selecting and Storing Scion Wood
Several nurseries sell scion wood. Other sources of unique varieties are commercial orchardists in NH and other home fruit growers. Scion wood is collected while trees are still dormant (usually in late February or March in NH). Scion wood should be straight and smooth and about pencil thickness (Fig. 2). Water sprouts that grow upright in the center tops of trees are ideal.
Once cut, trim to 12-18” lengths, and place in a food-grade plastic bag. Place a damp paper towel or sphagnum moss in the bag to maintain moisture, seal, and place in the refrigerator until you are ready to graft, usually in mid- to late April.
Many newer varieties of apples and pears are patented. Propagation of patented varieties requires the permission of the patent holder along with a royalty fee for each new tree created.
Whip and Tongue or Bench Grafting
A technique commonly used for spring grafting is whip and tongue grafting, also known as bench grafting. Whip and tongue grafting can be used to add multiple varieties to an apple or pear tree already growing in the home orchard. Because this technique involves joining wood of equal or nearly equal diameter, generally about pencil thickness, whip and tongue grafting is done near the ends of branches.
To complete this graft, you will need a sharp knife and either grafting tape, masking tape, or a plastic strip to seal the graft. The first cut is a smooth cut approximately 1¼ to 1½ inch long, made with a single knife stroke (Fig. 3). This cut is made on the rootstock several inches above the top root. A matching cut is made on the bottom of a 5-6 inch long piece of scion wood.
The second cut is a bit more difficult to make. Start by holding the wood as shown in Fig. 4. Starting at a point about ⅓ inch down from the tip of the cut surface, cut down into the center of the rootstock. This cut should be nearly parallel to the grain of the wood (Fig. 4). The bottom of the scion should be prepared in exactly the same fashion as the top of the rootstock.
Join the two prepared pieces, scion and rootstock (Fig. 5). Push the two together firmly to insure a snug fit and good contact. Finally, wrap the new graft union to protect tissue from drying. Masking tape is one option. Another is specially developed grafting tape. (Fig. 6). I prefer to use 1 inch wide strips of plastic cut from bread bags. Start below the newly formed union, stretching the plastic slightly as you wrap around and up over the union. This will help insure a moisture proof seal. Once the union is completely covered, tie the plastic strip off with a simple knot. A healed whip and tongue graft is shown in Fig. 7.Figure 5: Scion and rootstock are joined to complete the graft. Figure 6: The completed whip and tongue graft, sealed with grafting tape
Newly grafted trees are set out in a nursery row to grow. The home vegetable garden is an ideal place to grow these trees out for a year or two until they are large enough to plant out in their permanent location. When planting grafted trees, be sure to set the graft union 2” (Fig. 8) or so above ground to ensure that the scion does not root.Figure 8: Set trees so the graft union is a couple of inches above ground. If the scion (variety) roots, a large tree will result.
Cleft grafting is a technique that produces a union between a large rootstock trunk or limb and a much smaller scion. Using this method, an older tree can be top-worked to change to a more desirable variety.
For this method, scion wood is collected and stored as described for whip and tongue grafting. Again, this grafting is done in April in NH.
The first step in cleft grafting is to prepare the older tree for top-working. The tree is cut off at a convenient height, usually 30 inches or so above ground (Fig. 9). Alternatively, individual branches within an older tree can be top-worked using this same technique.Figure 9: Older apple tree, cut off about 30 inches above ground in preparation of cleft grafting.
Using a hammer and either a cleft grafting tool designed for this use or alternatively, a hatchet or chisel, a split or cleft is made in the wood (Fig. 10). This cleft is then held open using the end of the cleft grafting tool designed for that purpose, or a screw driver or similar tool (Fig. 11).
Once the stock is prepared, scions are cut and inserted to complete the graft. Two scions are prepared using pieces of pencil-thick, year old wood, approximately five to six inches long. The bottom of each scion is prepared by making a single, smooth, sloped cut on each side (Fig. 12).Figure 12: Bottom of scions used for cleft grafting. The thicker side should be set to the outside of the stock.
These scions are set into the cleft, one on each side, positioned so that the cambial zones of the stock and scion ‘line up’ or touch (Figs. 13, 14 and 15). It is important to note that the bark of the stock is much thicker than that of the scion. The key is to line up the cambial zones, not the outside edge of the bark of each.Figure 13: The knife point marks the cambial zone of the stock. It separates the bark from the hard wood inside. Figure 14: Scion properly inserted into cleft in stock, assuring cambial zone contact. Figure 15: A completed cleft graft - sealing with grafting compound is the next step.
If the stock is larger than four or five inches in diameter, I like to insert additional scions using a technique called inlay or bark grafting. Scions are prepared as shown in Fig. 16. Again, a four to five inch scion is used. A one-inch long cut is made up the middle of the scion from the bottom, and one side is removed. The other side is often tapered at the tip to make joining the scion to the stock easier.Figure 16: A scion prepared for use in inlay or bark grafting.
Place the flat, cut surface of the scion flat against the stock and trace the sides into the bark of the scion with a knife. Then cut the bark in all the way to the hardwood using the tracings as a guide. Carefully peel back the bark and slide the scion in until it seats (Fig. 17). Using the bark flap as a cushion, nail the scion in place using a wide headed, wire nail (Fig. 18).
Insert scions up to every four inches in stock circumference. After a scion has been placed in each side of the cleft and inlay grafts have been added, all cut surfaces must be covered to prevent drying of sensitive cambial tissue. Use a commercially available grafting compound for this purpose. Check newly made grafts for several days to insure that no holes in the grafting compound have opened (Fig. 19).Figure 19: Grafting compound must cover all cut surfaces of the stock and scion. Be sure to cover the cleft or split in its entirety, including on the side of the trunk.
What Comes Next?
If the grafts were made correctly, most will grow, some quite vigorously. These grafts will be brittle for a few years, so proper training is important.
The spring following grafting, select two successful grafts and join them together by wrapping the weaker one into the stronger one and tying it off with black plastic electrical tape. Over time, these wrapped shoots will graft together and create a very strong, natural bridge (Fig. 20).Figure 20: Wrapping the two successfully greafted scions together creates a very strong structure.
Proper tools and supplies make the grafting job easier. There are several good grafting compounds on the market. Those that do not need heating are easier to use. While a hatchet can be used to make cleft grafts, a cleft grafting tool is relatively inexpensive and makes the job easier. Lastly, A sharp knife is your most important grafting tool and it makes sense to purchase a high quality one.
Download the Resource for the complete fact sheet and a printable version.
Espalier Training Question: Can I Graft Two Living Trees Together? What Will Happen?
I am going to attempt to make an espalier fence ( image1) with my grafted apple trees that I planted about month back. I have no experience what so ever doing this other then what I am reading about on the internet. I am pretty sure I can do this but I have a question that I can not find the answer to so I am going to see if any here has attempted this or has any knowledge on this subject.
I have 6 different varieties of apple trees already planted in the ground that are 11 feet apart. What would happen if in the years to come when the branches on each row came close enough to connect I decided to graft them together ? ? This would then so to say link all 6 trees together side by side all the way down the line . Would there be any benefit to connect them together and would there be a downside to connecting together ? ? ? I will attempt to make a drawing of exactly what I am talking about so you may get a better idea. I am not an artist so please bare with my drawing
I will be making the espalier fence with cables running from one end to the other so that I can train the trees along the same wire. Image 2 is my ( so called Pablo Picasso drawing ) where I was thinking about joining them together.
Fascinating! I don't know nearly enough about grafting trees to give an answer, but I'm really curious to see if anyone with more experience knows. I know traits from one tree transfers to another via grafting (which is why rootstock can give disease resistance and stature traits to the tree grafted to it). I also wonder how you'd graft them together. Would you graft them into a Y or just straight into each other, so they each dead-end into each other?
I attached my horrible rendition of trees getting grafted.
If you Google "tree shaping" you'll find all sorts of pictures and articles about how to bend and fuse trees to become a single entity.
Here's an article from the UK Permaculture Magazine that talks about it.
So, yes, it's possible to do what you are proposing. Some trees like willows and sycamores take to being shaped and fused much easier than other varieties.
Check out these images to see the vast range of possibilities.
"The rule of no realm is mine. But all worthy things that are in peril as the world now stands, these are my care. And for my part, I shall not wholly fail in my task if anything that passes through this night can still grow fairer or bear fruit and flower again in days to come. For I too am a steward. Did you not know?" Gandolf
Yes you can join trees as long as they are from the same family (apples in this case), as David mentions, there can be draw backs but these are not usual.
Living fences have been joined for centuries and many of the old ones are still thriving after a few hundred years.
To join them all you really need to do is expose the cambium layer where the branches cross and then tie them together, use some Elmer's white glue to coat the joint to prevent insects and disease out and you are good to go.
You can use rubber band material to tie them and that will rot away around the time the wounds heal over. If you use cordage then you will want to keep an eye on the wraps so that you can change them as the branches grow together so there isn't any deformation.
List of Bryant RedHawk's Epic Soil Series Threads We love visitors, that's why we live in a secluded cabin deep in the woods. "Buzzard's Roost (Asnikiye Heca) Farm." Promoting permaculture to save our planet.
Years ago I saw a tunnel like arbor made entirely out of fused pear trees. The trees were 8' on center and arched up to about 11' high where they curved over and were grafted to the tree on the opposite side and the branches were trained laterally and grafted together. The tunnel was filled with pears and cooler than outside the structure.
If you look up some of the Bonsai techniques you will see various techniques for grafting two separate plants of the same species , most are done by removing bark carefuly
Doing it as they grow from young plants that are already established is one way .
You are best to decide how far apart your " fence posts " will be , then plant the young trees that far apart . Put your post mid way in between the saplings & run the straining wires between the posts without too much tension on them .
Start to train a " leader branch " in spring wern things are supple & full of sap . Make them lightly & softly fastened to the the wire guide to the adjacent trunk at the height that they grow or gently use the straining wires as anchors to secure a cord tied lightly to a branch thats at a slightly different height . It's up to you how you do it , two low leaders off one trunk supplying a tree on either side or only taking one leader off each trunk & taking it to just one sapling at each level .
One interesting way is to use a slow speed battery drill or a sharp hand borer and bore a hole with a wood boring twist drill an inch or so into the trunk the diameter of the leader that you have decided to grow where it will enter the new trunk .
You usually take it off an adjacent tree using grafting wax & self amalgamating rubber tape to seal the hole & keep the leader in place in the new trunk .
A demonstration I saw was where a long leader from the top of a young tree it was gently slowly but surley has been pulled right down in a letter " P " by hand then pulled through the hole that went right through the trunk , sealed with grafting wax , braced with 5 mm dia Bonsai soft wire that had bee run through some soft plastic tube to stop it cutting in at the points of contact to secure it and left to grow .
This was done to make two new low down branches to balance th tree in later years . It can also be used to put two lateral leaders in low down .
Again where the leader passes through the drilled trunk you will need to remove outer & the inner bark in the prescribed manner so you have only exposed the Cambian layer showing . Don't over do it and cut too much out so you only have wood left . they won't grow .
One side of these cleaned of bark ( At the point of joining only ) leader must be a good contact fit to the cambium layer of the host tree so use a caliper to measure the diameter to discover what drill size you will need .
It's worthwhile spending a few hours or so learning how to cut the outer bark off then shaving the inner bark to understand what the cambium layer looks like on each particular tree.
If you go too far and cut everything out till you only have the wood of the tree , there will not be any path of nutrients to pass through & the cutting / graft will fail
Most of these sort of graftings are done in early spring when the sap starts to rise in the host plants as the growing season then gives you a far greater chance of the host pant accepting the newcomer .
Re disease on your tree fence ..
If there is any disease that will totally kill a single tree off in a single attack then yes it could be a problem ..happily there are not many such diseases that cannot be treated using natural products that fully comply with the sites ethos .
As you'll have many trees close together most of the time any other disease can be cut out and the bare wound sealed with a simple sealing compound .
If I graft two trees together while young, will they grow as one plant? - Biology
California, United States
What to do when two trees are growing very close next to each other? For instance, we have a bunch of trees that are competing, such as an oak and eucalyptus, ash and oak, etc. All volunteers over time but previous owner let them grow. I read that a little competition is good, but what about when 10 ft tall trees are growing 12 inches apart? Cut out the one you don't want?
Exactly, take out the one you don't want. but remove the stump or use stumpkiller, or it'll start growing again.
10 feet is nothing in the life of those trees - if they are left the trunks will be touching each other and pushing for space before many more years have passed. One tree allowed to achieve its full shape will be more pleasing in the end than four or five crowded together.
'Houston, we have a problem'
At 12 inches apart, you cannot remove the stump without compromising the tree you are trying to spare and I would advise NOT to use stump killer in this instance. The roots are intertwined and trees exchange food & water underground and so they will the stump killer too, killing both trees. Just cut the sacrificial tree down as low as possible, then use a stump grinder to finish the job. You can rent one real cheap or hire an arborist.
Here is an article you will find extremely interesting: http://blog.drwile.com/?p=14646
Any application of stumpkiller to a cut down tree stump will only kill that actual tree - there is no process of osmosis or translocation that will transfer the stumpkiller to other, separate tree roots nearby, so long as the stumpkiller isn't poured by the gallon onto surrounding soil. In point of fact, grinding out stumps and roots is more likely to cause damage to other trees if not done with care,but grinding them out is still the best option to prevent honey fungus infection.
There actually is a process of translocation but not through osmosis, it's through the roots. Just read the article. Trees are living things and they correlate in remarkable ways.
Excerpt: That means the mycorrhiza transferred the photosynthesis products of the exposed trees to the roots of the unexposed trees! In addition, the researchers found that these photosynthesis products even ended up in trees that were of a different species than the exposed trees!
Stump grinder is just for the stump. Don't worry about the roots, they will naturally decompose without upsetting the neighboring tree.
Link to this article please, Bathgate, I would like to read it having used stumpkiller on all sorts of woody trunked shrubs and trees growing in proximity with others down the years, I've never yet known any surrounding tree or shrub die as well, so I'm intrigued.
The link is right in front of you. Simply scroll up.
Here's another one, different source, same conclusion
Oh yea, sorry, missed it. hmm, well having read both links, I ain't convinced, its a great pity there's no link to the actual scientific results in dwile's blog. but extrapolating that, because an altered form of carbon had a 4% uptake in other trees, a poison will be transferred from one tree to another via mycorrhizae is not a reasonable theory to make from the information there. In my extensive experience, there is no uptake of stumpkiller by surrounding tree roots. I once used it on cut down stumps every other shrub in a 30 foot row of Prunus laurocerasus, because too many had been planted initially some years earlier, with no ill effect on the remaining plants. But we can agree to disagree, if you still think its a risk.
If I may add my thoughts:
Mycorrhizae do indeed assimilate products of photosynthesis using enzymes specifically for natural carbon compounds produced during this process. They then absorb these smaller molecules and then convert them into carbon compounds that they use for their own biology. In close association they also 'give' to roots of other plants.
However there is no evidence as far as I have found that shows mycorrhizae are able to absorb stump killer [too large a molecule to pass through the fungal membranes] and transfer it to neighbouring roots. They don't posses the enzymes to digest it.
I have been watching the research on this for many years now:systemic weed killers are also a case in point.
That's very interesting Seaburngirl. Amazing how a stand of trees will function as a single organism in many ways. I also read that a mother tree knows which are her own seedlings and will transfer nutrients and water to them through an underground network. There's so much more I don't understand, but this makes me stop and think.
I have successfully used SBK on weed shrubs entwined with landscape shrubs, without harming the one I wanted to keep. I will admit that they were small, compared to their bigger neighbors.
Seaburngirl - I assume that also means that systemic herbicides cannot be transferred via the mycorrhizal route? Would it kill the mycorrhizae growing in association with a particular root?
That's an interesting idea Paul. usually the majority of trees tend to inhibit the growth of their own seedlings too close to them as they will compete with the parent tree for light/water and nutrients. The concept is called alleopathy and lots of plants show this, though some do produce chemicals to encourage the growth of plants such as clovers.
Yes Bamboo that's is my understanding too. Fungicides work differently to herbicides as their biochemistry is different.
Not really, because the roots are also grafted together or fused together. read the article.
I did read the article Paul but as bamboo says lacks clear science evidence or ref to research. But the concept of alleopathy is genuine and once established commensalism does happen. But trees usually disperse their seed some way away from them to avoid competition.
I don't know the full science behind it either, there's much to be discovered, but the underground network is extensive and complex. I can drive from New York to LA, or I can go to Boston, or the Big EZ. It's just a matter of what roads I choose.
I studied Botany & Zoology at uni so I understand the science behind plant growth etc That's why it's disappointing there aren't the links to the original research so I can read it to a greater depth. I still have contact with the botany dept and regularly attend seminars to keep my ɿinger on the pulse' so to speak.
Please may I ask a related question? I have mint roots which have grown along a crevice which now needs filing with mortar. I'm trying to remove all the mint from that area. I would like to kill the roots before doing the mortaring and am worried about whatever I use leaching out to planting at the end of the crevice. Any advice about what would be safe to use would be very much appreciated, with a apologies for muscling in on the question -seemed a good idea when the experts are all assembled!
I know you are smart Seaburngirl. I just added a little humor to lighten the mood. I like the idea of driving down to the Big EZ aka New Orleans. I don't think we'll ever fully understand how it all works.
sadly my geography is appalling so the destinations didn't make any sense :o) So sorry I missed the humour I didn't know what/where the Big EZ was Paul. My uk geography is not much better. Unless I have been there or need to go there I haven't a clue. I dropped geography aged 13 :p Hated the teacher.
Stera if you use a glyphosate weedkiller and perhaps use a paint brush to add it carefully to the plant stems then it wont contaminate neighbouring plants. These weed killers are absorbed by the plant and translocated down to the roots. In the past I have used a fine crochet hook to try to pull out stems. The lime from the mortar is just as likely to leach out. but unless you have extremely sensitive acid loving plants it wont be a problem.
FYI, Sbg, "the Big Easy" is New Orleans, Louisiana's nickname. What makes it so easy is beyond me--especially after Hurricane Katrina! Maybe just the fact that, like where I live, shoveling snow is an unknown! :)
Nothing to do with liquor / gambling and prohibition then? well I live and learn.
why is new York the big apple? don't understand that either :o)
It seems more like a big onion
I've been interested to read your conversations above. I've recently been reading about this theory regarding trees communicating and supporting one another. It's fascinating. A good example is of the Acacia Trees in Africa which put out a bitter taste in response to being nibbled. Then all the other trees that haven't yet been nibbled start doing it as well, so the Giraffes have to go some distance before they can feed on the same kind of trees. Wonderful isn't it? Makes you think. if they can do that. what else do they get up to? I'm no scientist of course, I don't have the brain wiring for it. But I am confident that the boffins will get to the truth of it in good time. In the meantime, it makes me think twice about being violent to trees in any way! :) When I moved here I wanted a multi-stem Birch, but the nursery advised planting three, one foot apart. So in a few years I will know whether they can grow happily so close. A few years ago I saw an amazing sight in a woodland. a great big tree with a smaller conifer growing right out of it. must have seeded in between two roots. And the way it was growing it looked just like the large tree was protecting the conifer. Wish Iɽ taken a photo! Love Trees :)
EDITOR’S NOTE from AZT: In response to numerous questions about why Arid Zone Trees has, thus far, elected not to produce grafted desert trees species we offer the following article originally published in the Journal of the International Society of Arboriculture. While we continue our own experimentation, in the absence of credible research or long term study of grafting in desert tree species, we remain skeptical of this practice. Arid Zone Times would like to thank Peggy Currid, Managing Editor, Arborist News Magazine, International Society of Arboriculture, and the author Professor John Ball of South Dakota State University for their permission to re-print this article.
By John Ball, Professor of Forestry and the Forest Health Specialist at South Dakota
Ornamental trees endure many stresses in the urban landscape. Some of these stresses, such as night lighting, are unique to the urban environment and do not have any close natural counterparts, which makes such stresses particularly troublesome to detect and mitigate. While arborists are familiar with many of these stresses, there is one that probably is rarely considered: Our urban trees suffer from a split personality.
Arborists often are guilty of considering only the “top” of the tree when diagnosing problems. The leaves (or lack of them) and the condition of branches and trunk are evaluated, but sometimes we forget that part of the tree is beneath us, and that portion requires evaluation as well.
The first step in any diagnostic process is identifying the species. Simple, you say: If the top is a white ash (Fraxinus americana), the roots must be as well. Wrong. And here is where the split personality problems begin.
One glaring example of the perceived non-importance of roots is the fact that rarely can we identify the “bottom” of ornamental trees. Most ornamental trees are actually two trees: The trunk and canopy are one species the roots another. These trees are cultivars—a group of cultivated plants distinguishable from other plants of the same species by any characteristic and that retain the characteristic through propagation. Two common cultivars found in the urban landscape are Autumn Purple white ash (F. americana ‘Autumn Purple’), known for its outstanding deep purple fall color and October Glory red maple (Acer rubrum ‘October Glory’), selected for its crimson-red fall color.
Cultivar trees are propagated by a grafting technique called budding. A single bud taken from the desired cultivar is nestled within a fold made on the lower stem of a seedling. Once the bud begins to expand the following spring, the seedling stem above that point is pruned away. The initial sideward growth ensuing from this single bud results in a slight stem crook that remains visible for several years or longer. (NOTE: If you cannot see the crook, there is a good chance the tree has been planted too deeply.) The top of the tree, referred to as the scion, originates from this single bud—a bud taken from a specific cultivar, a tree with known characteristics. The bottom, the root stock or under stock, is beneath the scion and consists of the lower few inches of the stem and the entire root system. The origin of it is usually a mystery. You’re never sure of the characteristics of the root stock. Sometimes you are not even sure of the species.
When you plant an Autumn Purple white ash, you probably are placing a green ash (Fraxinus pennsylvanica) in the ground. Most white ash cultivars have been budded onto green ash root stock. Green ash commonly is used as the root stock for many ash species, including European ash (F. excelsior), white ash, and black ash (F. nigra). Green ash is so often used as the root stock for these other species that it might even be referred to as a “universal donor.”
Grafting two different trees together does not always work. Grafting between species within the same genus, such as white ash on green ash, works for a number of genera. Grafting between species of different genera, but within the same family, is possible only for a limited number of species. One bi-generic combination occasionally seen in the landscape is Mountain Ash (Sorbus ¥ hybrida) on hawthorn (Crategus monogyna) root stock. Sometimes a homeowner is surprised to find thorns coming from his or her mountainash. The thorns are not coming from the mountain ash, of course. Rather, the hawthorn root stock has suckered and those stems have thorns.
A number of anatomical, biochemical, and physiological barriers prevent successful grafting between different families—for example, an oak (Fagaceace) on a maple (Aceraceae). These barriers exist even for most bi-generic combinations. Bradford pear (Pyrus calleryana ‘Bradford’) budded onto common pear (P. communis) often will fail.
Also, there are well-documented cases of graft incompatibility when the scion and root stock are of the same species but from different plants. Red maple (Acer rubrum) and Freeman maple (Acer ¥ freemanii) cultivars probably are the best examples of this problem, though the problem also occurs with oaks (Quercus spp.).
Graft incompatibility can be expressed as delayed incompatibility in which the failure of the graft does not occur until five to ten years after budding, when the tree is no longer in the nursery but in the landscape. It is not hard to find maple trees at 3 or 4 inches in diameter that died from delayed incompatibility. The symptoms of incompatibility are premature (and often spectacular) fall color, dieback, and eventual death—with the death sometimes occurring as the tree snaps off at about 3 inches (the height of the bud union).
The delayed incompatibility problem is not limited to maples and oaks. It can occur in conifers as well. Yews (Taxus spp.) sometimes die from incompatibility problems years after planting, as can Douglas-fir (Pseudotsuga menziesii). Delayed incompatibility is more common on grafts between species within a genus. For example, Bradford pear on common pear root stock may fail several years after planting.
The problem of incompatibility cannot be fixed once the tree is in the landscape. The solution is back at the nursery. Therefore, it is best to consider planting species such as red maple, where delayed incompatibility is a major concern, on their own roots. Many nurseries propagate these trees as cuttings so that the tree is on its own roots and have identified them as such in their catalogs.
Even when the grafting is successful, problems can occur. With the mountainash— hawthorn combination, the different characteristics of the scion and root stock sometimes become apparent. This problem is common with crabapples (Malus spp.). Crabapples are a popular ornamental, with numerous cultivars selected for their form, flower, fruit, or resistance to disease. Most crabapple cultivars are budded onto apple or crabapple seedlings. These root stocks frequently send up suckers that can grow extremely fast and, if not removed, can outgrow the cultivar within a few years. Sometimes homeowners are reluctant to remove these small suckers they like the idea of developing a multi-stemmed tree.
Have you ever had a client remark that when his or her crabapple was young, it had pink flowers and small yellow fruit, but now it produces white flowers and large, red, mushy fruit? The tree did not change, but the apple root stock out competed the crabapple cultivar. If you look in the center of these clumped crabapples, you’ll sometimes find the stunted—but still living—cultivar.
The solution in such cases is to remove the young suckers that sprout from the root stock. Some root stocks sucker profusely therefore, you may have to perform this procedure annually. You can reduce the number of suckers by delaying pruning until just after the leaves have completely expanded. Pruning during the dormant season invigorates sucker production no differently than renewal pruning of shrubs in late winter results in an abundance of new shoots. Products such as Sucker Stopper™ can be sprayed onto the fresh cut to retard the development of suckers.
Root stock does not always end 2 to 3 inches above ground. Many weeping forms of trees, such as tabletop elm (Ulmus glabra ‘Pendula’) (Figure 3) and weeping mulberry
(Morus alba ‘Pendula’), are budded onto a root stock about 5 to 6 feet above ground. Any buds that form on the root stock of such trees must promptly be removed these quickly growing buds can shade out the weeping cultivar as they grow.
Ornamental trees endure a number of unique stresses in the urban landscape. The split personality problem is one not shared by their forest cousins. While it is not a major stress, it is probably one of the more unusual ones. When you’re examining a tree, don’t assume the “top” and “bottom” are always the same.
When two tree branches or stems grow in close proximity to each other, it is possible that they&rsquoll eventually grow large enough to touch. If the bark becomes abraded, say through rubbing caused by swaying in the breeze, it is possible for them to become physiologically &ndash or functionally &ndash connected. This is the basis for grafting.
People have been grafting plants for thousands of years, most commonly to propagate desirable traits such as flower color, fruiting, size, or shape by intentionally joining together two different plants. But both shoot and root grafting occur naturally in trees, without human assistance. In fact, some scholars have suggested that horticultural grafting practices first emerged as early humans attempted to mimic the natural grafting they observed in the wild.
The result of grafting, either natural or horticultural, is a genetically composite organism functioning as one plant. That is, grafting results in the creation of a compound genetic system by uniting two or more distinct genotypes, each of which maintains its own genetic identity throughout the life of the grafted plant. This is why, for example, a branch of a red-flowering rose grafted onto a white rose stock will continue to produce red roses rather than white or pink hybrid roses.
Here&rsquos how grafting works. Just under the bark of all woody plants is a layer of living cells called the cambium. These cells divide and multiply to create bark tissues to the outside of the cambium, and wood tissues to the inside. This is how tree roots, stems, and branches grow larger in girth. And it is the most recently created of these cells on each side of the cambium that perform the vital functions of transporting water and minerals gathered by the roots from the soil up into the tree, and the carbohydrates made in the leaves down into the rest of the tree. Think of the cambium layer as the tree&rsquos plumbing.
When the plumbing system of one tree successfully fuses with that of another, a graft union is formed. But this can only happen under specific conditions. First, the tree parts have to be biologically compatible. That&rsquos why such fusions are more common among the branches, stems, or roots of one tree or between two individual trees of the same species. But it can happen between two trees of closely related species. The more different the species are taxonomically, the less likely a graft can occur between their parts. Indeed, no such grafts have ever been documented between tree species in differing families.
Other requirements for this amazing bit of tree magic are that the tree parts be in direct, prolonged contact be under pressure have sufficient moisture and protection from the elements, insects, and pathogens and have those cambial cells properly aligned. Okay, it&rsquos biology and not actually magic &ndash but it might as well be considering how many things have to go right for it to work. Among northeastern tree species, natural shoot grafting is known to occur in sugar maple, black cherry, red and white oak, sycamore, willows, beech, eastern hemlock, and white pine (as pictured).
It should be noted that there are many occurrences of branches or stems growing very closely together, even touching in what would appear to be a graft union, but that turn out to be separated by layers of bark. These are not true graft unions, because they lack physiological connectivity. The one in question here would appear to be a true graft because the lower portion of the one stem appears dead, while its upper part appears to be alive and well, suggesting a physiological reconnection has occurred. Ah, the near-magic of tree biology.
Michael Snyder, a forester, is Commissioner of the Vermont Department of Forests, Parks and Recreation.
© 2013 by the author this article may not be copied or reproduced without the author's consent.
Tags: northern woodlands, tre.
When two trees grow into each other, or fuse, does one become more dominant or do they both continue to grow together?
If one becomes more dominant does it completely take over the other tree or does it take over more from where they join upwards? If they grow together to what level of independence do they each have?
In most cases of fusion (insoculation), it just happens at a single point where already mature limbs come into contact and rub together until the cambium is exposed. So in those cases, while there might be a little bit of vascular exchange, it wouldn't be much and the trees would still be almost entirely independent.
If you're referring to trees like this recent post at /r/MarijuanaEnthusiasts where two separate trunks fuse vertically and become a single trunk, I'm not aware of any published research that attempts to answer your question. It's something I've thought about every time I've found a vertically insoculated tree, though. They're uncommon, but it happens enough that you could study it fairly easily.
First, though, we need to define what we mean by "more dominant."
If it's about the genetics of the tree, it should be pretty easy to determine if one of the cell lines has completely encircled the trunk and all cambium and downstream tissue have a single genome, while the other cell line is not contributing anything genetically beyond the point where they've fused. (Of course, that's only easy to determine if they have different genotypes. In many cases, it's two stump sprouts from the same root system that do this, so there probably wouldn't be any way to determine cell line contribution using genetics.)
Dominance could also refer to physiology, though. And even if the tree is genetically all one individual beyond where they fuse, the other trunk's root system would have to still be contributing to water and nutrient uptake and receiving sugars since the roots and trunk below below the fusion point do continue to live. In fact, that other trunk might even have the dominant root system that's doing the most to determine the tree's overall health.
TLDR: Define your terms and let's set up this research and get it published!
Apple tree diseases
While apple trees are very hard, there are a few diseases that may affect apple trees. The best defense is a healthy tree. Maintaining proper soil conditions, adequate water levels, and fertilization can help your trees thrive.
Here are a few diseases to avoid:
Fire blight is a bacterial disease that causes branches to blacken, giving them a scorched look, and will kill the tree eventually. You can control this blight by either choosing trees that are genetically resistant to the disease, or removing blighted branches off the tree.
Powdery mildew attacks the foliage and fruit on apple trees. It is a white fungus that will appear on the leaves, fruit, and flowers. If left untreated, it will eventually cause the tree’s health to decline. You can help control this disease by applying a fungicide to the tree during early spring, just as the leaves are starting to push out.
An apple scab is a fungus that leaves black soot-like spots on the leaves and fruit. This disease mostly affects new leaves in the spring, during moist conditions. However, it can affect mature leaves during May and early June.
The fungus appears as black velvety spots on the leaves. As a result, the leaves turn yellow and eventually drop.You can control this disease by either choosing disease-resistant apples, or applying fungicides as the leaves come out during the spring.
Cedar apple rust
Cedar apple rust is a fungus that leaves rusty spots on the leaves of the tree. This disease commonly affects Juniper, Cedar, and Apple Trees. When this fungus attacks Apple Trees, the leaves will develop small yellow spots in late spring. As the tree becomes more stressed, both leaves and fruit will drop off the tree prematurely. Cedar Apple Rust cannot be controlled once the tree is infected.
Some trees will grow back after being cut near to ground
I have fruit tree pruning classes at 1 p.m. Fridays and 9 a.m. Saturdays during the month of December at Ahern Orchard in downtown Las Vegas. Class size is limited so you must enroll on Eventbrite or contact me.
I have fruit tree pruning classes at 1 p.m. Fridays and 9 a.m. Saturdays during the month of December at Ahern Orchard in downtown Las Vegas. Class size is limited so you must enroll on Eventbrite or contact me.
Q: If a dogwood were cut off a few inches from the ground, would a new dogwood tree grow from the stump? This is a theoretical question, but I’m talking about a wild dogwood that was transplanted into a landscape in Virginia, where these plants normally grow wild. The tree was transplanted from its wild location several years before it was maliciously cut down.
A: Flowering dogwood will sucker from its base after it has been established. How do I know this? I looked it up. So cutting this plant 8 to 10 inches above the ground results in sucker growth that can be used to create a new plant.
Sometimes I cut plants shorter than this, but it depends on the plant. After cutting it back, you must prune it during the first couple of years to create a desirable plant in future years. This means removing undesirable growth while it is young.
But this brings up an interesting question: How do you know if a plant will sucker from its base or not if you can’t look it up?
Plants have three options when they are cut nearly to the ground: grow from the base vigorously, grow from the base slowly or not sucker at all because this plant doesn’t sucker and you’ve killed it. There is a fourth option for grafted plants. Plants grafted to different roots, called a rootstock, may send up suckers from below the graft. This type of new plant may be worthless and should be removed.
For the first two options, look at the base of the plant. Are there suckers already present or not? If it is less than 5 or 6 years old, the presence of suckers tells you this plant can be cut back, leaving a stump or stumps, and it will sucker vigorously from this stump.
Some plants grow slower than others. For instance, if this kind of pruning were done to oleander it would grow back vigorously making a new shrub in a year. In the case of Texas ranger, it grows back slowly so it might take two years to re-establish itself.
Some plants, such as most fruit trees and some ornamental/shade trees, are grafted so that this graft makes a union between two trees. The top tree is called the scion and the bottom tree, used for its roots, is called the rootstock.
There is a characteristic dogleg that eventually grows where the two plants are joined together. If the pruning cut is made 10 or 12 inches above this dogleg, any growth from the scion can be kept but any growth below — or from this dogleg — should be removed.
Most commercial fruit trees are grafted to a rootstock. Many shade trees like ash and flowering plum are grafted the same way. Some ornamental trees, such as southern live oak, are not. Look for the dogleg to be sure.
Q: I have one purple leaf plum tree with very few leaves and another with lots of leaves. I was told the reason it has few leaves is that I am watering only the trunk of the tree. This tree is watered twice daily for eight minutes on a trip system. The second purple leaf plum tree also gets full sun all day and the same watering schedule, but it’s full of leaves. What am I doing wrong?
A: Watering might be the only problem if your tree was growing anywhere but in the Mojave Desert. Here there are two potential problems: irrigation and desert soils. But your watering schedule sounds skimpy and too frequent.
Desert soils can create problems for nondesert trees even though the tree is getting enough water. To make sure, the tree roots from this tree should be growing into soil that has compost mixed with it. Too late for that to happen? Read on.
A second contributing problem can be caused by the rock covering the soil after the tree was planted. Purple leaf plum is a nondesert plant and covering the soil with rocks easily contributes to many future plant problems.
Purple leaf, or ornamental plum, is not a desert tree like vitex or desert willow are. Rock is frequently used to cover the soil surface in desert landscaping. But using rock on the surface of the soil around purple leaf plum can create problems in about five years after planting.
If this is the case, try vertical mulching around this tree. If you want to keep the rock, rake the rock away from the tree at its base a distance of 3 feet from the trunk. Drill or auger vertical holes in the soil about 18 to 24 inches from the trunk and to a depth of about 2 feet. Fill these holes with compost, water it, and replace the rock. Otherwise, remove the rock from this area, fill the holes with compost but replace the rock with woodchip mulch.
The wrong amount and timing of irrigations can also create this problem. Minutes of watering doesn’t tell me anything. These trees need between 7 and 15 gallons after they are first planted from a 15-gallon container. Water application varies with the time of year but watering in midsummer should only be three to four times a week, not daily.
In about three to four years, the amount of water applied should be increased to 20 to 30 gallons. The number of times it’s applied each week doesn’t change. Increasing the amount is accomplished by adding more drip emitters under the tree canopy and further from the trunk, not increasing the number of minutes.
But eight minutes of water under the best conditions only gives the tree perhaps 2 to 4 gallons each time it’s irrigated. Watering trees twice each day may be convenient but it is a bad idea.
Q: We planted a sweet broom shrub in March of this year and it did very well. This fall I noticed the leaves were gone and only tan spikes remained. I found the culprits: 11 caterpillars doing the damage. I used a soap and water spray and the next day they were dead.
Two days later I picked off 25 more caterpillars. I then switched to a rose and flower insect killer and killed these. But 10 days later I picked off 25 more. I didn’t think desert plants got caterpillars. This is crazy! What should I do?
A: It’s a common misconception that desert plants don’t get bugs. They do. Sometimes they get more bugs than plants not native to the desert. That’s because their pests are here to begin with and they easily migrate to desert landscape plants.
This is probably the fall webworm. They lay eggs on the bottom sides of leaves and spin webbing around where they are feeding. This webbing makes a water- and bird-resistant tent where they feed protected. These caterpillars can keep coming back for several weeks during late summer and fall. Sometimes they don’t.
Soap and water sprays kill any bug, whether it’s a good bug or a bad bug. It’s a powerful insecticide. But it has one major disadvantage. It doesn’t last long. Once it is sprayed, this killing machine is finished. It doesn’t persist. To be effective, it must be sprayed over and over, every few days, when these bugs are seen.
Conventional insecticides, like the one you selected, is different from soap and water sprays because they persist. This is a good thing and a bad thing. It’s good because you don’t require spraying as often. It’s bad because it sticks around in the environment longer.
Another possible spray to use is Bt. It is not organic, but it is a natural pest control product. It persists longer than soap and water but not as long as most conventional insecticides like the one you were using.
Sweet broom is a good desert landscape plant. But it does have this problem so keep on the lookout in the spring and fall months for this pest and be prepared to deal with it when it arrives.