The Forbidden Apple Tree Knowledge Thread

[Native Hunter]

Back on the old QDMA forum I had a thread about apple trees that some people loved and have asked me to post on this forum so that they would have access to the scientific information that I spent many hours researching.

When I started that thread I had a question and a hypothesis.

In science, hypothesis is a tentative statement about the natural world leading to deductions that can be tested. If the deductions are verified, the hypothesis is provisionally corroborated. If the deductions are incorrect, the original hypothesis is proved false and must be abandoned or modified. Hypotheses can be used to build more complex inferences and explanations.

"Fact" in science is an observation that has been repeatedly confirmed and for all practical purposes is accepted as “true.” Truth in science, however, is never final and what is accepted as a fact today may be modified or even discarded tomorrow.

By the time I finished my research, it was my personal opinion that my hypothesis had been proven as fact.

Note: The following is where I pieced together (cut and pasted parts of) the information in the original thread. I realized later that I should have copied the whole thread, but I didn’t do that. What I have included is what I consider to be the important information.

Note: The forum only allows me to enter a limited number of characters at a time, so I have to make multiple posts to get all of this done.

The Original Question I posed with partial research: Why do we have so many issues (especially with fireblight) growing some apple cultivars that in the past gained such high acclaim and have been propagated for decades and maybe even centuries?

My Original Hypothesis with partial research: Every heritage apple cultivars started as a full sized tree on its own natural rootstock and was grown from a seed. When someone recognized a particular tree as something special and worthwhile for propagating, they were observing that tree growing on its own natural rootstock. Most of the time when that tree was propagated (by common country folks in the 1800s), it was from rooting a cutting of that variety or digging a root sprout, and the new tree also became a full sized tree that was essentially a clone of the parent tree in all respects at the molecular level.

When you read the wonderful stories about a particular old heritage apple variety, you are reading what was written about its performance and attributes as a full sized tree like I have just described. Many of those varieties were just as wonderful as the words that were written about them. However, some of those varieties – even though worth propagating – were not so great in terms of fireblight resistance, and the stories about them were exaggerated to some degree. They were good enough as full sized trees to be continued as a cultivar, but they were very marginal in disease resistance. But did the common country man at that time really care? There was no reason to care as long as they were producing enough apples and good enough apples to please the people who grew them.

I believe that it is many of those cultivars like I just described that give casual growers like most of us on this forum trouble today. Why – because we are not growing them as full sized trees but as dwarf and semi dwarf trees. They were marginal or borderline in their natural state, and when we started grafting them and growing them on dwarfing rootstocks we tipped the scales (possibly in multiple ways) to the unacceptable side (for us) due to several factors that I am getting ready to talk about.

Note: Keep in mind that what I am talking about here is for the casual growers like I believe most people on this forum are and want to remain. The main difference between us and the 1800s homesteader is that we are also concerned about producing apples for deer and other wildlife. Both groups (us and them) want/ed to also grow apples for human consumption, but for them it was more of a necessity.

My discussion here is not for the professional grower who must go to great lengths to spray and perform special activities beyond the scope of the casual grower in order to produce apples of supermarket quality. I suspect that with enough spraying and care that almost any apple could be successfully grown, but I really have no personal interest in becoming a commercial grower.

 

[Native Hunter]

Factor #1 (Reduction in Vegetative Growth): Several scholarly papers in recent years have touched on how vegetative growth of some apple cultivars is affected by the type of rootstock to which they are grafted. In a paper found at http://www.virtualorchard.net/IDFTA/...ril/page46.pdf the following quote is made:

“Dwarfing rootstocks, in simplistic terms, reduce the amount of scion dry weight. This effect is achieved by a reduction in both the rate at which vegetative shoots grow (extend) and the time period over which they grow. Compared to an invigorating rootstock, a dwarfing rootstock directs a greater proportion of dry weight into fruit production rather than into vegetative growth. We do not know how this is achieved, but if dwarfed shoots grow more slowly and do not grow for as long during the season, then dwarfed scions might be expected to have less leaf area than those on vigorous rootstocks. The effects of a reduction in leaf area means that scion shoots on dwarfing rootstocks may produce less photoassimilate relative to scions on vigorous rootstocks. Differences in the way leaves are orientated on the tree may also influence their ability to intercept solar radiation and convert this into fruit production via photosynthesis. Factors such as these may contribute to the observed reduction in tree size associated with dwarfing rootstocks, but they do not necessarily explain differences in the way dry weight is partitioned between tree growth and cropping.”

While the above statement does not totally prove my theories, the wheels in your brain must surely be spinning – wanting to know more. I certainly feel that way. I rationalize that when fireblight destroys a portion of the limbs on a tree, the future survival of that tree depends somewhat on the vegetative growth that it is able to produce in order to replace that which was lost. Could it be possible that on some (marginal) cultivars that the suppression of vegetative growth to accomplish that task might tilt the usefulness of that cultivar for the casual grower toward the negative side of the scale?

I was not able to grow the “Mrs. Bryan” cultivar successfully on M111. The above seemed to be a factor. So much limb area had to be removed on that tree each year due to fireblight, it seemed that the tree could never catch up with what it lost. Plus, the central leader would always be affected and much of it had to be removed. The result was a struggling, misshapen tree that was finally discarded.

Yet, common people grew that apple successfully at one time, but they grew it as a full sized tree.

Factor #2 (Percentage of the Total Tree Affected in the “Shoot Blight” phase): Imagine with me for a minute the smallest dwarf apple tree in existence setting next to the largest apple tree in existence. Imagine that both of them enter the shoot phase of fireblight and that the shoots are affected down to a diameter of the ½ inch range.

Which tree is affected the most in terms of total area?

Obviously, the small one. In fact, with this much shoot blight damage, the central leader of the small tree is likely affected an in jeopardy. However, the large tree is only affected at the distant limb ends. (Note: I am not ignoring that there are other forms of fireblight infection besides the shoot blight stage. But for this specific point, I am focusing entirely on that factor. I am well aware that rootstock susceptibility and other factors are important, but for now I’m talking about surface area only.)

Most of us on this forum are growing semi dwarf trees rather than the smallest dwarf trees like I used in the example above, but the point made still applies – just to a lesser degree. If a certain cultivar struggled with fireblight in its natural form but was still able to be a worthwhile tree, will it still be a worthwhile tree if a larger percentage of its surface area is affected (and perhaps its central leader as well) when a strike occurs? Common sense tells me in some instances it will not.

Factor #3 (Subjection of New Tree to “Shoot Blight” Phase at an Earlier Age): I have observed over the years that shoot blight mainly occurs when (or just after) an apple tree is flowering. I’m not bold enough to say it’s impossible without flowering but I can say that I personally have been around apples all my life, and that is my observation. With a full sized apple on its natural rootstock, the years of growth before flowering and fruiting starts taking place can vary, but I think 10 – 15 years is an average number that most would agree with.

However, on a semi dwarf tree, I have seen flowering and fruiting begin as early as 2 years in the ground and by 3 years, flowering is highly likely. Does that really mean anything? I don’t know for sure, but does the fact that a tree must start dealing with fireblight at a more youthful state possibly play a role in its long term survivability and health? Even the rootstock itself may not be fully developed by that time (depending on the particular rootstock).

This may or may not be a significant factor to consider, but if it is a factor, I can’t see how it could be anything other than a negative one.

 

[Native Hunter]

Factor/s #4 (Other miscellaneous Items): Other miscellaneous things that I read about and observe bring up questions that I long to have answered. The same paper cited above at http://www.virtualorchard.net/IDFTA/...ril/page46.pdf makes the following statement:

“Some rootstocks alter flowering time and this may be due to changes in the chilling requirement of different rootstocks.”

Since shoot blight infections most frequently begin at the flowers, could the fact that the flowering time is altered on some apple cultivars have an effect (positive or negative) on the degree of fireblight infection that a tree must endure in any given year? Fireblight strikes are heavily dependent on weather conditions, and weather conditions are at least somewhat dependent on the time of the year. That last statement is not speculation – it is scientific fact!! So when man alters the natural blooming time of a particular cultivar, could he also alter the degree to which it is affected by fireblight?

Also consider the following statement from the same paper just cited in the paragraph above:

“Our understanding of how rootstocks influence scion vigor, flower induction and cropping must, therefore, be improved. Attempts to explain the rootstock influence in terms of a graft union effect on the translocation of minerals or water, or those due to differences in root anatomy, have not proved satisfactory. Recent studies have suggested that rootstocks may influence scion growth and cropping by direct or indirect effects on plant hormones, either via synthesis, metabolism or transport from root to shoot and from shoot to root.”

WOW, did you get that??? Now we are talking about effects on hormones, synthesis factors, metabolism factors and changes in translocation of minerals or water. And did you catch that effects could exist that not only cause changes in transmission from the rootstock to the scion, but also from the scion to the rootstock?

I certainly can’t fully explain these factors, but neither can the experts. But, I see enough to tell me that at least some cultivars on at least some rootstocks may not necessarily be the same creature we were dealing with before man interceded in the natural course of things.


From the report found at: http://bmcgenomics.biomedcentral.com...1471-2164-13-9 the following conclusions are quoted:

"In this study, we found that rootstock genotype influenced 'Gala' scion fire blight susceptibility in grafted apple trees. This indicates that at least some level of resistance possessed by the rootstock can be conferred upon the scion variety that is grafted to it. These phenotypic differences in scion fire blight susceptibility were associated with reproducible patterns of gene expression in uninfected trees. Most of the transcripts identified in this study had higher levels of expression in the least susceptible trees. The expression levels of some of these genes may play a role in determining the susceptibility status of apple trees to E. amylovora prior to infection. Some of the identified genes may also play a role in fire blight disease resistance after infection has begun. It is also possible that some of the genes identified in the study affect the suitability of the host environment for the bacterium, rather than being involved in defense directly."

While all of my theories are not precisely proven by this study, it was proven that rootstocks do influence the susceptibility of grafted Gala scions to fireblight. I contend that if it is true for Gala scions, there is a high degree of probability that it will be true for other cultivars as well. I think anyone would have to be crazy to believe otherwise….

 

[Native Hunter]

Further Research by the end of the old thread that I feel proved my points (to my personal satisfaction):

My research also led me to an old paper from NEW YORK STATE AGRICULTURAL EXPERIMENT STATION that supports many of my theories. The quotes below are found at the following link:

https://ecommons.cornell.edu/bitstre...pdf?sequence=1

“Fireblight
This disease was not ordinarily a rootstock-related problem with the standard tree for several reasons:

1. Since on trees with standard roots, flowering did not begin until the trunk and scaffold system became quite large, a blight lesion then developing on the trunk or scaffolds was relatively unlikely to result in girdling.

2. Heavy shading limited the development of fruit spurs on the trunk and main scaffolds. This virtual absence of blossoms on the primary tree structure reduced the possibility of initial infections occurring there and therefore there was little chance of a girdling lesion developing.

3. With the wide spacing between trees and between rows, inoculum had to be transferred considerable distances between source and infection court.

4. Most seedling roots are inherently somewhat resistant to fire blight. Perhaps more important, by the time flowering began, shade was so dense that rootstock suckers were succulent for only a short period each spring.

Our change to the new rootstocks has altered the picture:

(1) Trees on most of the clonal stocks begin bearing at an early age, when the tree is still small enough that a single canker on the rootstock can girdle and kill it (Fig. 3).

(2) Many vigorous fruit spurs are set on the lower trunk and scaffolds while
these are still of small circumference. Fire blight cankers are likely to develop from infected flowers, and these cankers can extend laterally enough to kill a substantial part of the tree. (3) With closer spacings, bees tend to work down a row, rather than on a single tree; inoculum may thus be distributed much more efficiently.

(4) Most serious, some of the rootstock clones are themselves extremely susceptible to the fire blight bacteria.”

More from the same paper quoted above:

“At least three mechanisms may be identified by which certain rootstocks contribute to severity of fire blight in the fruiting variety:

1. Most of the clonal stocks, especially M.9, M.26, and MM. 106, accelerate the onset of flowering in the scion variety. Therefore, more infection courts are available earlier in the life of the tree.

2. The downward extension of a fire blight lesion is limited, in part, by the "hardening" of the stem. Shoots of trees on MM. 106 rootstocks tend to grow relatively late in the summer and to be come "hardened" weeks after trees on M.9 stocks. Fire blight lesions in trees on MM. 106 roots tend to continue basipetal extension for a much longer period than in trees on M.9 roots; in addition, shoots are susceptible to initial infection for a longer time.

3. Empire, Mclntosh, Idared, Monroe, and Jona than are examples of fruiting varieties which typically produce fruit buds on 1-year-old spurs. When one of these varieties is grown on M.9, M.26, and (sometimes) on MM.106 rootstocks, many of the lateral buds on new growth differ entiate into fruit buds. These lateral fruit buds open 3 to 7 days later than the normal spur buds. This phenomenon prolongs the bloom period—the period during which the blossom blight phase of the disease is initiated. In addition, weather during this late bloom tends to be warmer and therefore more conducive to the development of the disease. Additional sprays may be indicated when considerable lateral flowering occurs.”

I also want to make one more statement in regard to science. I am a firm believer in proven science, and many times I base beliefs and opinions totally upon the scientific evidence. The laws of physics (science) are an everyday part of the calculations that I do in my job, and you can count on these law always being what we believe them to be in our natural world (except in the case of divine intervention).

However, I think there are people in our society who rely so much on science that they miss the obvious just because someone hasn’t performed a study or research project. It’s a form of blindness that leaves me shaking my head. Or as my grandpaw used to say, “He wouldn’t know the truth if it walked up and slapped him in the face.”

 

[Native Hunter]

In summation, I think what all this means to the casual apple grower is that great care needs to be given to picking apple cultivars that work on dwarfing rootstocks. I think most of us already know that and try to do it, but don’t be misled into believing that any apple that gives acceptable results as a full sized tree on its own rootstock can be grown to our (casual grower) satisfaction on any given dwarfing rootstock. Also keep in mind that any glowing stories you may read about a particular variety could be exaggerated to begin with and that you could be starting with a marginal apple that tips the scales to unacceptable performance for you on a different rootstock.

I have one more axe to grind, so I might as well get that out of the way now:

Centuries ago, wise and just men realized that “only telling the truth” was not good enough as testimony in the legal system. I’m not certain who actually coined the phrase I want to discuss, but it’s one we all know…”the truth, the whole truth, and nothing but the truth….”

Now, just for the fun of it, let’s apply that standard to our current discussion:

First let’s tell the “truth:” Dwarfing and Semi Dwarfing rootstocks can offer many wonderful advantages over full sized trees.

Now, let’s tell the “whole truth:” Dwarfing and Semi Dwarfing rootstocks can offer many wonderful advantages over full sized trees, but there are also many pitfalls and problems that can be encountered. This is especially true when grafting fireblight susceptible cultivars. And, some rootstock / cultivar combinations are almost sure to bring disastrous results in some locations – depending on several different factors. Great effort should be given to gaining knowledge of these important factors before purchasing trees and/or choosing components for grafting activities. This is going to be difficult for you, because it's not kosher to talk about. Several people have the knowledge to help you but they won't, because it means less money in their pockets.

Now let’s cover “nothing but the truth:” Hello Mr. Apple Tree Buyer. My name is Mr. Apple Tree Seller. I must warn you that the wonderful and brilliantly composed stories on my Web-site about the apple cultivars that I sell could be very misleading. Those stories are about apple trees that were grown as full sized trees. Even though I am selling you the same cultivar, I want you to know that it is a scientific fact that my trees may not perform as wonderfully on my rootstocks compared to the same cultivar on a standard rootstock. You could end up with serious problems - especially with fireblight.

Now I could go on and on and on with this nonsense, but I’ve made my points. Being right is sweet, but now having the knowledge is even sweeter.

Good growing and may God Bless you – Steve

 

[Native Hunter]

Every so often a glaring mistake surfaces - so glaring that it cannot be hidden - such as the article linked below about the guy who lost 3,000 apple trees because of an incompatibility issue. Common sense would dictate that there are many other such combinations, many have been identified, but the average guy has no access to the information. It wouldn't be kosher to call attention to this.

http://www.goodfruit.com/problematic-pairings-with-geneva-935/

Recently I ran across what I felt was an interesting article that in a round about way supports this. The article is not really about this subject, but rather it is an article about how hard the Infamous Honeycrisp apple is to grow. Yet, the demand is so high from the yuppie supermarket apple crowd that growers feel they must grow it to survive.

The part I found interesting is shown below and the entire article can be found at this link:
http://www.growingproduce.com/fruits/apples-pears/the-dark-side-of-honeycrisp/

" ...Rootstock choice impacts how productive the variety will be. Since it is a low-vigor cultivar, larger rootstocks can cause Honeycrisp to become biennial bearing. DeEll says some rootstocks also cause trees to break off or cause nutrient deficiencies...."

If we believe that this is a problem only with Honeycrisp, we have our heads in the sand.

So there you have another bit of forbidden knowledge - "Incompatibility." But why worry? Just spend more money, buy a bunch of different trees and some of them will work out. Just chalk up the ones that don't to helping the economy.

I can probably stomach this with apple trees, but I hope it doesn't start happening with ammunition....

 

[yoderjac]

Great thread. I remember reading it before. I've got my own hypothesis but no proof. It is not in conflict with yours but it may account for some of what we see.

Apple pests have very short lifecycles and pathogens even shorter. This means that adapt very quickly to changes in their environment than higher-level longer lived organisms. Apples that are grown commercially are not only generally on a dwarfing rootstock, but they are clonal propagated and generally grown in large orchards. Because they are clonally propagated, they are genetically fixed in time. When a pest or pathogen adapts to advantage it over the tree, those adaptations are even more strengthened generationally by the fact that they apply to a very large group of identical prey (apple trees). The trees don't have the normal genetic response because they are fixed by asexual reproduction.

Heritage varieties, on the other hand, although clonally propagated, are grown in much lower volume an concentration. The most disease/pest resistant trees we see are "wild" (naturalized) seedlings. They are both "full sized" trees and they are more genetically diverse.

Whether by your hypothesis or mine, I see lots of value in full sized trees for wildlife. The maintenance required for many apples caused me to put them pretty low on my list for wildlife permaculture. I finally started working with apples a couple years ago. My approach was to start by growing apples by seed: http://www.habitat-talk.com/index.php?threads/starting-apples-from-seed-indoors-how-to.6613/. I am letting some of those just grow as seedlings for good. Some, I am top working in the field but leaving a nurse branch. My thought here is that I get a full size tree with known fruiting characteristics. I'm selecting the most disease resistant varieties I can find. I also get to find out what kind of fruit the original seedling would have produced. If it is a good one, I can collect scions from the at nurse branch in the future to propagate that tree. Finally this year, I'm grafting DR known varieties to clonal rootstock.

I don't plan to maintain any of the trees once established. My hope is that the clonal rootstock will produce know fruit sooner to cover nearer term permaculture needs. My hope is that the untouched seedlings will cover longer term permaculture needs and be the most resistant. However, with seedlings you never know what kind of fruit you will get. I'm hoping the grafted seedlings cover the middle ground where I have full sized trees with known fruiting characteristics.

Time will tell. I love all the insights you've provided in this thread. Great thread!

Thanks,

Jack

 

[Native Hunter]

Great thread. I remember reading it before. I've got my own hypothesis but no proof. It is not in conflict with yours but it may account for some of what we see.

Apple pests have very short lifecycles and pathogens even shorter. This means that adapt very quickly to changes in their environment than higher-level longer lived organisms. Apples that are grown commercially are not only generally on a dwarfing rootstock, but they are clonal propagated and generally grown in large orchards. Because they are clonally propagated, they are genetically fixed in time. When a pest or pathogen adapts to advantage it over the tree, those adaptations are even more strengthened generationally by the fact that they apply to a very large group of identical prey (apple trees). The trees don't have the normal genetic response because they are fixed by asexual reproduction.

Heritage varieties, on the other hand, although clonally propagated, are grown in much lower volume an concentration. The most disease/pest resistant trees we see are "wild" (naturalized) seedlings. They are both "full sized" trees and they are more genetically diverse.

Whether by your hypothesis or mine, I see lots of value in full sized trees for wildlife. The maintenance required for many apples caused me to put them pretty low on my list for wildlife permaculture. I finally started working with apples a couple years ago. My approach was to start by growing apples by seed: http://www.habitat-talk.com/index.php?threads/starting-apples-from-seed-indoors-how-to.6613/. I am letting some of those just grow as seedlings for good. Some, I am top working in the field but leaving a nurse branch. My thought here is that I get a full size tree with known fruiting characteristics. I'm selecting the most disease resistant varieties I can find. I also get to find out what kind of fruit the original seedling would have produced. If it is a good one, I can collect scions from the at nurse branch in the future to propagate that tree. Finally this year, I'm grafting DR known varieties to clonal rootstock.

I don't plan to maintain any of the trees once established. My hope is that the clonal rootstock will produce know fruit sooner to cover nearer term permaculture needs. My hope is that the untouched seedlings will cover longer term permaculture needs and be the most resistant. However, with seedlings you never know what kind of fruit you will get. I'm hoping the grafted seedlings cover the middle ground where I have full sized trees with known fruiting characteristics.

Time will tell. I love all the insights you've provided in this thread. Great thread!

Thanks,

Jack

Thanks Jack. I really like how that you are tackling the apples in different ways. Some of those seedlings may not be good, but some may be better than anything else we have available now. Also, even though you have to wait longer on the full sized trees you grow, they will be of great value down the road, and the apples you are grafting on clonal rootstocks will give you fruit while you are waiting on the others.

Our approach is not that much different. I started in apples a little before you, but you knew way more about persimmons when I started getting interested in them.

In the apple world - I'm at the point now that I love experimenting. Trying the Northern Whitetails Crabs is an experiment that I love doing, even though I have no guarantee that they will work out in my area. This is why I stated in my other post that the list I currently have developed will be changing as time goes on. I hope it helps lots of people.

 

[yoderjac]

Thanks Jack. I really like how that you are tackling the apples in different ways. Some of those seedlings may not be good, but some may be better than anything else we have available now. Also, even though you have to wait longer on the full sized trees you grow, they will be of great value down the road, and the apples you are grafting on clonal rootstocks will give you fruit while you are waiting on the others.

Our approach is not that much different. I started in apples a little before you, but you knew way more about persimmons when I started getting interested in them.

In the apple world - I'm at the point now that I love experimenting. Trying the Northern Whitetails Crabs is an experiment that I love doing, even though I have no guarantee that they will work out in my area. This is why I stated in my other post that the list I currently have developed will be changing as time goes on. I hope it helps lots of people.

I went ahead and ordered 2 Franklin Cider Apples for Stark. They don't list them down to my zone, but I presume they simply have not been tried this far south. No guarantee with will do anything for me either, but others will see my results here and have a better idea if they want to try them.

Thanks again for this thread!

Jack

 

[sandbur]

If the information I received is correct, Baileys uses lots of dolgo for rootstock. Baileys supplies most of the local nurseries in my area.

Are ranetka rootstocks seedlings?

Is this use of seedlings for rootstocks helping the backyard, rural fruit grower in this area?

Metro, suburbanites, might use the dwarfing stocks.


Sent from my iPhone using Tapatalk

 

[Native Hunter]

If the information I received is correct, Baileys uses lots of dolgo for rootstock. Baileys supplies most of the local nurseries in my area.

Are ranetka rootstocks seedlings?

Is this use of seedlings for rootstocks helping the backyard, rural fruit grower in this area?

Metro, suburbanites, might use the dwarfing stocks.

Sent from my iPhone using Tapatalk

Art, I remember reading in another thread where you pointed out that there could be some variability in Dolgo seedlings. I agree with that. I have a tree I bought as a Dolgo, and it makes a green apple bigger than 2 inches that ripens in the mid summer. I wonder if it is actually a Dolgo seedling or if there was a mixup.

I don't know a lot about Ranetka, but I would assume it is just like Dolgo. You could have a rootstock that came from the original named cultivar or you could have seedlings from the fruit.

 

[sandbur]

If the information I received is correct, Baileys uses lots of dolgo for rootstock. Baileys supplies most of the local nurseries in my area.

Are ranetka rootstocks seedlings?

Is this use of seedlings for rootstocks helping the backyard, rural fruit grower in this area?

Metro, suburbanites, might use the dwarfing stocks.

Sent from my iPhone using Tapatalk

Art, I remember reading in another thread where you pointed out that there could be some variability in Dolgo seedlings. I agree with that. I have a tree I bought as a Dolgo, and it makes a green apple bigger than 2 inches that ripens in the mid summer. I wonder if it is actually a Dolgo seedling or if there was a mixup.

I don't know a lot about Ranetka, but I would assume it is just like Dolgo. You could have a rootstock that came from the original named cultivar or you could have seedlings from the fruit.

I have seen lots of variation in dolgo seedlings, but never a green two inch apple.


Sent from my iPhone using Tapatalk

 

[TreeDaddy]

Steve,

thanks for posting this thread

bill

 

[buckvelvet]

Ranetka is a Ranetka is a . . . ?
March 23, 2013
(Some Inconvenient Observations about Apple Rootstocks)

By Mark Weaver — December 2012

In the last 20 years, productive apple trees and productive home orchards have proliferated in Southcentral Alaska to an extent once thought impossible. In large measure, this has happened because of the willingness of a few Alaskan and Canadian growers—real pioneers in the pomological wilderness — to share their hard-earned apple experiences, and often as not, their scion wood. Perhaps the most significant pearl of wisdom passed on by these pioneer orchardists has been the importance of using “ranetka” rootstock — the ranetka having proven itself in the far north as vastly superior to antonovka, and to many other supposedly hardy rootstock apples, most of which fail to survive our cold summer soils and sub-zero winter frosts.

The beneficial impact of ranetka rootstock on Southcentral apple growing can hardly be overstated. It has acted as a catalyst, almost single-handedly enabling the production of hundreds of viable bench grafts each year at the APFGA spring grafting workshop, and a remarkable increase in the trees and cultivars represented at our autumn apple-tasting event.

At the same time, because of the relative success of northern growers using ranetka, there is a corresponding risk that we will become complacent in our thinking about rootstocks. I, at least, have been guilty of subscribing to a convenient myth — a myth so easily conceived and so compelling that it may have attracted the allegiance of others also. By way of warning (the faint of heart should stop reading here!), I choose to call this “The Ranetka Myth.”

The Ranetka Myth goes like this: Malus ranetka is a species of crabapple having M. baccata as one parent and M. prunifolia, or possibly Dolgo, as the other. It is hardy, it is vigorous, it is almost perfectly reliable as the rootstock of choice for Alaskan conditions, and it is conveniently available in seedling form, at low prices, from various nurseries in the lower 48 and from APFGA at the April grafting workshop. Use ranetka, and your orchard will prosper!”

I will move on to a key point of this article, which I call:

Heresy #1: Believing in the Ranetka Myth is a bit like believing in the Tooth Fairy. Or, to be more botanical, like believing that all brown mushrooms are edible. Why? Because the Ranetka Myth is dangerously overstated. It defies common sense and several well-established genetic, taxonomic, and economic principles. It ignores, or misinterprets, a considerable body of local experience. And, most significantly, it is potentially lethal — at least to apple trees.

Let me add some related points, each of them troublesome:

Heresy #2: As far as I can tell, none of the rootstock imported by APFGA and others in recent years is M. ranetka, or even M. x ranetka. Careful scrutiny of Westwood’s Temperate Zone Pomology (3rd ed., Timber Press, Portland, 1993) suggests there is no such species as M. ranetka. But if, by ranetka, we simply mean crosses of M. baccata x M. prunifolia, or possibly M. baccata x Dolgo, the rootstocks that we have been calling “ranetka” in recent years are not those either! Most likely, they are seedlings of open-pollinated crabs that may themselves be seedlings of open-pollinated M. baccata. Or they are seedlings of open-pollinated seedlings of open-pollinated seedlings of open-pollinated M. baccata … etc., etc.

Heresy #3: It is a mistake to give any domestic, seedling-propagated population of apple rootstocks a formal name, other than seedling #1, seedling #2, seedling #3, and so on. A formal name implies uniformity of characteristics like hardiness and onset of dormancy, and uniformity in apple seedlings (except in some wild populations) is a perilous illusion. Apple seedlings are inherently diverse.

As apple-growing readers doubtless realize, apples which are full siblings can be quite different in key characteristics. Norland and Parkland, for example, are full siblings–they are both Rescue x Melba crosses. Yet they differ in tree structure, taste, appearance, and other traits, including hardiness. Seedlings derived from trees that are open-pollinated, and that flowered in places where many cultivars — and species! — of apple are potential pollen donors, are likely to be even more diverse.

Heresy #4: The imported “ranetka” seedlings many of us have been using for rootstock are, not just theoretically but in fact, genetically and phenotypically diverse. They are variable in a number of observable traits, including leaf color, vigor, tree form, onset of dormancy, and most significantly, winter-hardiness. Moreover, a significant percentage of them are not hardy enough to withstand a Southcentral Alaska test winter — a winter with precipitous drops in temperature and little or no snow cover.

For emphasis, I will present the last statement in the form of a prediction:

Heresy #5: If we get a Southcentral Alaska test winter in the foreseeable future, there will be, come spring, an unfortunately large number of dead apple trees. Many will fail because of “ranetka” rootstock. Trees grafted on to the APFGA “ranetka” class of 2010 and 2011 will be particularly vulnerable, but some from earlier years will also die — if they are not already dead.

One more point, before I offer support for these pomological heresies (or am besieged by emails from angry apple-grafters): I sincerely hope I am wrong. Or, if not wrong, I hope that global warming will mean no test winters and thus few rootstock failures — in which case, my predictions can be laid to rest as the debunked rantings of an amateur. And I will not be offended; I will be tending my apple trees.

But now, the observations that I believe support the previous points:

Observation #1: “Malus ranetka” appears to be a misnomer, unless somewhere there are wild native populations of ranetka apples which have been taxonomically catalogued and named. Moreover, any seedling resulting from a cross between Malus baccata (which is a species, having a wild population with remarkably uniform characteristics and botanical descriptors that have been catalogued) and any other apple, should not be considered a species. It should be considered, like many apples, a seedling hybrid, and unless clonally propagated, it can be expected to vary substantially in both genotype and phenotype from other siblings resulting from the same cross.

Observation #2: Decades ago, Robert Garner, dean of grafting and longtime chief propagator at the East Malling Research Station in England, noted the disadvantages of seedling rootstock: “The chief disadvantages of seedlings are their propensity for variation and the impossibility of predicting the limits of this variability” (emphasis added). Garner went on to suggest that “the unpredictable variability of seedling rootstocks will probably not much longer be tolerated” (The Grafter’s Handbook , 5th ed., Cassell, London, 1988, 70, 76).

Observation #3: Many seedlings labeled “Malus ranetka” and/or “Malus x ranetka” (suggesting they were open-pollinated seedlings of a species named “Malus ranetka”) have been imported and distributed by APFGA and others from Lawyers Nursery in Montana. Two years ago, in December 2010, I telephoned Lawyers and inquired about the source and the parent material of the rootstock they had been selling as “ranetka.” I received a written reply, the complete text of which is (exact quote): “Thank you for your call. The Malus ranetka source is the Kiev region in the Ukraine. No additional information is available.” (Again, note the use of “Malus ranetka” as an apparent genus/species indicator, although as far as I can discover, no such species exists.)

 

[buckvelvet]

Observation #4 Bernie Nicolai, an Edmonton apple grower, has on more than one occasion pointed out that the term “ranetka” is a source of semantic confusion. He wrote the following in 2004 (emphasis his, quote taken from NAFEX online correspondence, Feb. 24): “[A]ccording to a friend in Siberia, ranetka is the generic term for ANY seedling that has Siberian Crab as one parent. They usually take the extreme hardiness from the Siberian Crab, and have small inedible fruit, and make great rootstocks in cold climates. The ranetka seeds Lawyers Nursery in Montana sells come from the Ukraine, and are simply Siberian x Domestic apples.”

I believe that Nikolai is correct in his assertion about what “ranetka” means, and what Lawyers sells. But I also believe he misses a key point about hardiness, which is:

Observation #5: Pomologists who study winter hardiness in apples have found that cold tolerance is genetically determined and additive. That is, in any population of apple seedlings, a majority will inherit cold hardiness traits that range between those of the two parents in a distribution curve centered on the mean (Janick, Cummins, Brown, and Hemmut, Apples; from Janick & Moore, Fruit Breeding; 1996, http://www.hort.purdue.edu/newcrop/pri/chapter.pdf, 40). Thus, a few seedlings will inherit traits that are approximately the same as one or the other parent. A very few may be hardier than the hardiest parent or less hardy than the least hardy parent. But almost all of the apple seedlings originating in Kiev — or in any other place — will be less hardy than their hardiest parent, and about half of the seedlings will be less hardy than the average of their parents.

Hardiness is obviously a complex cluster of traits, more complicated than simple cold tolerance, and more difficult to measure. Nonetheless, the implication of the above genetic principle as applied to imported seedling rootstocks is staggering. Consider the following:

Observation #6: Recent plant hardiness maps indicate that the Kiev region of Ukraine — the apparent source of many of our “ranetka” — is generally comparable to U.S. zone 5. If this is accurate, winters in Kiev are much like those in Iowa and southern Wisconsin. They are less severe than those in most of up-state New York and in most of the apple-growing areas of Minnesota. Obviously, many cultivars of apple (and hence, many pollen donors and many mother trees) that survive in Kiev that would not survive in Southcentral Alaska. Moreover, part of the Kiev region, less than a hundred miles south of the city of Kiev, is mapped as zone 6!

Observation #7: In the mid-1980s, Catherine Wright, an experienced plant propagator at the State Plant Materials Center in Palmer, Alaska, performed apple rootstock trials. Her results are published and available on the Internet. Notable findings include these: Survival rate of “M. ranetka”: 48% (more than 40 specimens tested). Survival rate of M. baccata: 61% (more than 70 specimens tested). Most fatalities were on three-year-old plants after the winter of 1985-86, which Wright considered a test winter. As far as I can tell, the rootstocks tested were seedlings obtained either from Lawyers Nursery or from government plant facilities in British Columbia and Washington state, but I have been unable to locate Wright to confirm this.

Observation #8: (complicated but critical) Several years ago, I began to apply principles of “forward funding” to my apple rootstock supply. Instead of immediately cutting and bench-grafting onto the bare root seedling “ranetka” I obtained from APFGA each spring, I simply planted the bareroot whips in pots, let them grow outside for a summer, discarded any weak or obviously problematic plants, and wintered-over the rest by tipping the pots before freeze-up to prevent ice damage. I planned to use them for rootstock the following spring. My thinking at the time was that I would get more reliable and vigorous graft growth on ranetka that had developed well-branched root systems and proven their vigor.

What I got—quite unexpectedly—was a high rate of winter mortality. This was not due to icing, or voles, or moose. It was due to simple winter-kill, resulting from a lack of hardiness. In the spring of 2011 (the wintered-over seedling class of 2010), the survival rate was only 50% on a group of about 20 whips. (Is an exposed-pot a tough winter test? Of course. But so is a winter in which the temperature drops below zero in late October with no snow cover.)

Observation No. 9: In 2011-12 (last winter), I again wintered over a “ranetka” seedling class from the previous spring (2011). In addition, I deliberately wintered-over more than 20 clonally propagated rootstock whips which I obtained by layering two 3-year-old “ranetka” (APFGA class of 2008) that had survived several winters in untended pots in a neglected part of the garden (think “well winter-tested” here). This gave me two additional groups of whips that were physiologically the same age as the new class of “ranetka” seedlings, but were genetic copies of winter-tested survivor “A” and survivor “B” of the class of 2008.

I treated the three groups identically throughout the growing season. As late fall 2011 approached, the pots of the clonally propagated whips were placed next to the pots of the seedling whips, so that winter conditions, especially amount of snow cover, would be identical. Visually, the three groups of plants—the two groups cloned from winter-tested plants and the new seedlings—were quite similar in size and apparent vigor.

In late March of 2012—last spring—I dug the three groups out of the snow and put them into the garage to warm up. The survival rate of the 2011 “ranetka” seedlings? Exactly 15 percent. Only 3 of 20 seedlings had survived. (The group originally numbered 25. Five were discarded for poor vigor before winter even began.) The survival rate of the “ranetka” clones, from my two winter-tested plants? 100 percent. Every single clone survived.

The conclusion is obvious: Not all “ranetka” are created equal. Some are significantly hardier than others, and those hardiness traits can be selected for and replicated through cloning.

Not All Ranetka Are Created Equal

This is from Alaska Pioneer Fruit Growers if you'd like to click that link to learn more about Ranetka. When Stu told me about Ranetka I decided to give it a try and the only place I cound find it (from Stu's help) is Walden Heights Nursery. Great people and the price was pretty reasonable. I did that back in 2016 and I have no complaints on the results and digging and transplanting my grafts on Ranetka the roots were ginormous after a 24 mo period in my nursery.

As you can see from the above writing though not all Ranetka is created equal, just like say a Dolgo seedling as a rootstock.

 

[buckvelvet]

http://www.habitat-talk.com/index.php?threads/1st-rd-done-of-grafting-complete.2930/post-168763

This should bring you to my post that shows my first hand 2 year nursery roots of B118 vs Ranetka. Very noticeable difference as Ranetka has 2 huge tap roots on each tree with smaller feeders as B118 as tons of feeders just not a lot of tap root.

 

[4wanderingeyes]

Native, I remember your post from the old site, and read it. It was when I was just starting out planting apple trees.I had planted 4 apple trees a couple years prior reading your post, then right before I was going to order more trees the next year I read your post. It was mostly over my head at the time, and to some degree still is, but it made me go out and buy only full size trees after that. My trees are just starting to produce larger amounts of fruit now, and I am seeing the payoff from the larger trees. For one, the larger trees will be a little harder for the bear to destroy, 2 I have seen no disease to date on any of my trees, and 3, my trees are a decent size before they start bearing fruit, so they are stronger to hold them.

As for the Dolgo's, I have planted 4 of them, and mine are all smaller like 3/4 of an inch, very tart, but after eating one, you need another. Two of my 4 trees had fruit on them the same your I put them in the ground, they were 7/8 caliper trees in the spring when I planted, and the fruit was falling off of them buy September. Then year 2 I only had a handful of apples on the Dolgo trees. This will be year 3, so we will see what this year brings.

 

[DLH]

Your thread here and our many phone conversations is what has lead me to try and get some apples on their own roots. Is there any full sized rootstocks out there that are truly clonal roots maybe P18? Cummins list it as bigger than m111 and b118. I know Antonovka is too but I was thinking that may be seedlings?

 

[Native Hunter]

Native, I remember your post from the old site, and read it. It was when I was just starting out planting apple trees.I had planted 4 apple trees a couple years prior reading your post, then right before I was going to order more trees the next year I read your post. It was mostly over my head at the time, and to some degree still is, but it made me go out and buy only full size trees after that. My trees are just starting to produce larger amounts of fruit now, and I am seeing the payoff from the larger trees. For one, the larger trees will be a little harder for the bear to destroy, 2 I have seen no disease to date on any of my trees, and 3, my trees are a decent size before they start bearing fruit, so they are stronger to hold them.

As for the Dolgo's, I have planted 4 of them, and mine are all smaller like 3/4 of an inch, very tart, but after eating one, you need another. Two of my 4 trees had fruit on them the same your I put them in the ground, they were 7/8 caliper trees in the spring when I planted, and the fruit was falling off of them buy September. Then year 2 I only had a handful of apples on the Dolgo trees. This will be year 3, so we will see what this year brings.

Thanks for sharing that information and keep us posted on your trees in the future. Sounds like you are off to a great start.

 

[Native Hunter]

Your thread here and our many phone conversations is what has lead me to try and get some apples on their own roots. Is there any full sized rootstocks out there that are truly clonal roots maybe P18? Cummins list it as bigger than m111 and b118. I know Antonovka is too but I was thinking that may be seedlings?

DLH, that would be a good question for future research. I think the fear with lesser known rootstocks is something happening like the article I shared where a guy lost 3,000 trees due to an incompatibility issue. I've never heard a bad report on Antonovka, other than people getting impatient for the trees to fruit.