I have been caring for bonsai trees for the past 12 years and I wouldn't recommend fertilizing trees in the fall.

Trees are not like your lawn which can store the nitrogen in it's roots.

If you fertilize your trees now you will be chemically telling your trees to grow grow grow when the seasons are signaling for your trees to prepare for sleep(winter).

If you fertilize your trees now you run the risk of killing them.

If you intend to fertilize your trees your should consider fertilizing in the spring after the tree has leafed out and during the growing season but stop short of fertilizing in fall.

I personally like to feed my trees fish emulsion which has all the major and micro nutrients. If you follow the suggested formulation with water it is nearly impossible to over do it.

I wouldn't recommend using lawn fertilizer as it is too high in nitrogen and has to little phosphorous and potash.

You can also try mulching around your trees which will improve your soil in the long run.

No, fall fertilization doesn't stimulate late growth that delays hardening off- even very late summer fertilization doesn't, but the myth lives on. I've included a link on the subject. Maybe mid-summer excessive N is dangerous but I haven't seen research on that one way or the other.

Trees store N in the buds and fall application can help the trees get off to a more vigorous start, but the advantage over spring application is negligible for a very young tree- it is more about getting N to the spur leaves to serve the developing fruit the following season, although a late summer or fall foliar application may be helpful for a stressed tree (according the the article of the link).

Generally, the most efficient N application is applied to the ground in early spring at about the time of first growth- that is when the roots are most capable of taking up N. In commercial orchards, fall is usually when K is applied to replace that taken out by the years crop.

That isn't to say that juicing the trees with extra water soluble N is always helpful and that mulch can't supply the tree with what it needs for very (sometimes excessively) vigorous growth.

Here is a link that might be useful: fall fertilization

Harvestman...if it is a myth (I'm not saying it isn't) then there must be a mass conspiracy among the authors of fruit growing literature. I have read this very same thing Mr.green has alluded to hundreds of times. I've read it not only in the growing of fruit trees, but in trees and shrubs in general. To me, it makes sense. I've read it in very old fruit growing literature (circa 1860's) and very recent stuff as well. I have (at least I think, I have) caused damage to my trees from this very thing. I'm an excessive fertilizer by nature...it's a sort of affliction of mine.

The article even mentioned foliar applications to trees that have begun rapidly defoliating. I do not believe that foliar applications of N to trees that have already began dropping their leaves will do anything at all other than waste fertilizer and time. Do you agree? Surely you do...right? I'd be interested to know how many commercial growers actually followed this advice, and furthermore how many continue the practice.
This research was conducted by two people ( and likely loads of assistants) and I'm not sure that their conclusions are weighty enough to topple long standing conventional growing wisdom.
Perhaps my mind is poisoned by reading this so much and so often that I'm incapable of seeing beyond it.
I can however understand the K ground applications you mentioned and P as well....but foliar N? Mehhhh
Fertilizer costs too much for me. Mine will stay right in it's bag/box/can until spring where I know it will do some good.

Appleseed,there are many horticultural myths that make sense- that's why they keep getting passed along. There are also pedigreed horticulturists that enjoy debunking these myths through research- men like Carl Whitcomb. And then there is the industry that relies on accurate information to compete in the difficult realm of commercial fruit production.

You read a lot, but if you read the link I provided more carefully they mention September N applications, not just fall applications and the N must hit active leaves to be absorbed by the buds, it is pointless to make these late applications to nearly defoliated trees.

If you search for it you can probably find something about similar applications to apples and other plants- here's something I found in 60 seconds on general fall fertilization of landscape trees.

Stop believing everything that is written and focus more on the research and you won't go quite as crazy trying to figure this stuff out. Gardening is a subject that is written about very carelessly by hacks that believe they have it figured out- maybe I'm one of those but I invite you to correct me with actual research derived information.

I suspect the reason trees are not so susceptible to this kind of damage is because the exact same thing happens when there is early summer drought followed by late rain- that actually does create a lot of late vegetative growth (there is a sudden surge of available N as well as water in this situation), but it is mostly just those late shoots that are likely to be damaged by winter. In my nursery, only the shoots of J. plums suffered on a season this happened but all the trees survived a relatively harsh winter.

Trees are much more likely to be killed by winter if they go into it LOW on energy.

Here is a link that might be useful: affect of fall fertilization on winter hardiness of landscape trees

Harvestman, I read the link ok. I didn't say "nearly defoliated"...I said (as did the article) "rapidly defoliating". Cherry trees drop their leaves sooner than most, don't they? September probably is Fall in Michigan, September has been Fall here in Maryland a few times.

I get what your saying about gardening being carelessly written about. We've all read things that were crap. I don't see where this proves the articles merit, but instead rather draws it's conclusions into question. Depends I guess on where one thinks the carelessness resides.

My experience with water soluble fertilizers are that the leaves or plants must be green and actively growing for it to be effective. Well before dropping leaves I'd guess most of the growing aspect is over. No doubt some N would be taken up, but how much?

Conventional wisdom said eggs were good for you. Then researchers got involved and said they weren't. Then they said the whites were good for you but the yolks bad. Now they are saying eggs are good for you.
Something everyone else already knew for centuries.

Just out of curiosity I'm going to risk my cherry and try it this year. Maybe I'll be surprised.

Interesting discussion. I would like to try it on my 1st year cherry too.

Appleseed70,
Can you go a little more detail how are you going to experiment? formula? timing?

I am thinking spray MG-GP at the outdoor concentration from its label. After terminal bud is set (just to be safe, so no more new leaves and shoot growth), while 100% leaves are green. What do you think?

Also interestingly. Rutgers NJ Agri experiment station publish every year about timing for sweet cherry..
http://njaes.rutgers.edu/pubs/plantandpestadvisory/2009/fr100609.pdf
http://njaes.rutgers.edu/pubs/plantandpestadvisory/2010/fr092110.pdf
https://njaes.rutgers.edu/pubs/plantandpestadvisory/2011/fr091311.pdf
http://njaes.rutgers.edu/pubs/plantandpestadvisory/2012/fr090412.pdf
Thanks

Alex

This post was edited by FruitNewbieNYC on Thu, Aug 28, 14 at 17:02

AS, splitting hairs, the point is they recommend application while the trees are in leaf not while rapidly defoliating. The suggestion is to do it right away if leaves happen to be rapidly defoliating, so how i can you construe that as an issue to the discussion of whether earlier application can be harmful?

Healthy cherry trees have plenty of leaves in Sept- (in Jersey, at least) I just pruned some 3 weeks ago that I looked at yesterday and they are still in full leaf now. And the pruning stimulated no new vegetative growth (pruning creates the same response as N ap. because the same amount of N goes to much less leaf).

And the other point is that the idea that late summer N fertilization harms a trees ability to harden off has never in any way been established in research (that I've seen) and has now been pretty much disproved by research (that you've now seen). Please find me a single piece of research that says otherwise or just accept the research I've presented as the most likely conclusion. It would be so much easier for both of us (joking).

It's not really helpful just to say that research could be wrong when you don't even have any anecdotal evidence that suggests it.

Harvestman-

Thanks for the article. I think I will give a Sept foliar feeding a try. I will likely use ammonium sulfate, as that is what I have available as the nitrogen source (and some fish emulsion as that keeps the deer away).

That article mentions 40# of urea as the amount to use, but they don't specify on what area. I'm assuming that would be per acre.

If that's the case, then 40# of urea has 18.4# of N or roughly equivalent to 88# of ammonium sulfate. So with ~40k sq ft per acre, that would mean roughly 2# of ammonium sulphate per 1000sq ft. Seems like an awful lot as that is roughly the footprint of a full sized apple tree.

Does this math sound right?

Steve:

Foliar ammonium sulfate? I think that will defoliate your trees. Furthermore I don't think fall nitrogen is necessary. Done properly it won't hurt but unless your trees lack vigor it's not needed.

Two lbs AS foliar on a tree will likely knock the leaves off in short order. Even urea needs to be low biuret. Might not have that spelled right but it needs to be specially pure urea.

Fall nitrogen doesn't force growth because trees naturally stop growing in response to shorter days and cooler temperatures. A natural survival mechanism. Many locations can have severe fall freezes and many fruit trees have developed this defense.

Harvestman, you seem to be taking the stance that I'm attempting to disprove you...I'm not and have been very careful not to. You offered this piece of "research" as proof that late fertilizing in no way holds trees vegetative beyond normal..thereby putting them at risk to winter injury or dieback. That's what you said to mrgreen. I merely stated that I too have read much of the same as mrgreen.

You seem to think that because a university conducted research that it somehow topples everything folks previously thought and wrote about for perhaps hundreds of years. It also seems to me that you think this because they simply called it RESEARCH. Anyone can call anything research harvestman...you know that. Think about the egg issue. I also don't get your splitting hairs thing...I never "split hairs", I repeated; almost verbatim what the study said.

The suggestion is to do it right away if leaves happen to be rapidly defoliating, so how i can you construe that as an issue to the discussion of whether earlier application can be harmful?

I'm, NOT construing anything. I'm simply saying that I'm very doubtful (mind you not saying they are wrong...though I do want to) about their beneficial claims when fertilizer is applied when a tree is dropping leaves...and a FOLIAR application none the less. The focus of the article is applying to sick trees to begin with, so how then do you construe this to disprove mrgreens premise? You are twisting this study something terrible...it doesn't address the issue at hand AT ALL. I don't think you are doing it intentionally, I think you are simply misinterpreting the data...and worse...data that some might think questionable.

Healthy cherry trees have plenty of leaves in Sept- (in Jersey, at least) I just pruned some 3 weeks ago that I looked at yesterday and they are still in full leaf now. And the pruning stimulated no new vegetative growth (pruning creates the same response as N ap. because the same amount of N goes to much less leaf).

OK...so your HEALTHY trees in JERSEY in AUGUST have full green leaves now ? What does that mean? How does that compare to sick trees in Michigan in September. I just pruned an apple less than 3 weeks ago and it DID stimulate new vegetative growth. If you like I'll be happy to post a photo tomorrow when it's daylight.

And the other point is that the idea that late summer N fertilization harms a trees ability to harden off has never in any way been established in research (that I've seen) and has now been pretty much disproved by research (that you've now seen). Please find me a single piece of research that says otherwise or just accept the research I've presented as the most likely conclusion. It would be so much easier for both of us (joking).

Nothing has been disproved harvestman...nothing. I'm under no compulsion to accept anything. I'm also not going to go hunting conflicting "research", though I have no doubt I could...no doubt. Where is the proof you speak of...where? Where are the scientific details in this report? Must I send off for them as noted at the bottom of the article? If I were to do so, would I expect to get a scientific analysis PROVING that mrgreens (and almost everyone else's) position on the matter is indeed a myth? Would this report be using a control group over the span of several years measuring die back on both the fertilized and unfertilized trees?
The answer is NO...no it would not. It would not because that was not the focus of this supposed research in the first place. Furthermore they have suggested things like foliar fertilizing of trees at beginning leaf drop. To me, that calls into question anything further they might have to say. Again, I'm in full knowledge that I may very well be wrong and I've stated this repeatedly.
If Michigan state published some new "research" stating that you harvestman would not sustain any injury when jumping from a 100 story building...would you do it comfortably because you are armed with their empirical research stating you'll be ok?
Probably not.

It's not really helpful just to say that research could be wrong when you don't even have any anecdotal evidence that suggests it

What on Earth are you talking about? Are you kidding me?

Fruitnewbie...the more I think about it, I'm going to pass on this experiment. I don't know how I could ever evaluate the results. For example: this year my lone tart cherry had no leaf spot issues or any other for that matter and has been lush and beautiful. I didn't fall fertilize it, but had I done so, I might have erroneously concluded the foliar fertilization a success when it was not.
The three people listed in harvestmans MSU study were:
Dr. Greg Lang MSU Horticulturalist
Theoharis Ouzounis Phd Chemical Engineering
Marlene Ayala Phd Economics

So you see, this study is really that of 1 guy...a horticulturist. Also, a great deal of their study videos is done within a retractable roof greenhouse. I think all of the videos in it was involving cherries. They mention a few sites in the article, but I wonder if any of the data was derived from research conducted on those trees under cover?
There really is just no way to evaluate results from 1 tree or even many trees on just one site in one year.
Contrary to Harvestmans position on the subject (though I greatly value his opinion on many things) I do believe the far more expansive list of folks (also having doctrates etc) who warn against late season fertilization. They mention Montmorency in the article. Montmorency's leaves are so shiny and slick, that most foliar applications would run off to be later absorbed by the roots if it hadn't leached away by spring. Sure...there may under certain circumstances (sick trees as in the studies case), odd weather etc be a benefit from late season fertilization, but the risks coupled with the uptake vs. cost ratio just isn't there imo. I may be wrong, but I bet few commercial growers engage in this practice.
I'll take proven conventional wisdom any day over that compiled by an economics professor. Where's Alan Greenspan when you need him?
I was waiting for one of the names mentioned to turn out to be a midget on a unicycle...just joking.

Appleseed, have you even made a search for research in the last 20 years on this subject?. You make me batty by talking about all the qualified experts who support your position without providing a single recent reference that is related to research or anything at all beyond your recollection of claims made. This discussion is pointless if you are simply stubbornly holding on to what you believe, without attempting to back it up with actual information.

The fact is that untold millions of acres of lawns are fertilized around labor day with high N fertilizer all over the country every year by people who are often not competent of doing the math when trying to distribute a pound of actual N per 1,000 square feet. This is a frequently proscribed quantity.

If nitrogen applied at this time actually represented a meaningful threat to winter hardiness of woody perennials cooperative extensions would be pushing back about the dangers with numerous articles documenting winter killed trees and shrubs in landscapes.

I have been using fall fertilization in my own orchard and scores of those I manage for a couple of decades- through mild and test winters and mortality rates are very low and the trees are very healthy. It is a good way to get N. to the spur leaves on bearing age trees.

As I said, the research I linked you to I found in a minute search- I'm sure I could find a lot more but am waiting for you to do some homework to back up your opinion instead of simply stubbornly holding on to an old horticultural myth because it makes sense to you.

I suggest you purchase the book, "Arboriculture" by Richard Harris, published by Prentice Hall.

Harris is an advocate of fall fertilization and the source that originally steered me to this method of nutrient management. Harris was (or is) a Professor Emeritus at UC Davis and his book is by far the best source of researched information on the care of woody landscape plants currently available in English that I've ever seen.

You should read this book about three times. That is how many times it took me to feel like I really had absorbed most of the important information in this outstanding text book.

Appleseed, have you even made a search for research in the last 20 years on this subject?. You make me batty by talking about all the qualified experts who support your position without providing a single recent reference that is related to research or anything at all beyond your recollection of claims made. This discussion is pointless if you are simply stubbornly holding on to what you believe, without attempting to back it up with actual information.

Harvestman, it is you who is droning on about qualified experts, while discrediting the scores of those who have for years warned of late fertilizing...I made exactly one reference to it...one. You claim I have not provided a single reference to support my position. NEITHER have you, until now with the Harris reference. Your cited study DID NOT study this...AT ALL. You just now made reference to Harris' book which I've not read, but I'll take your word for it that he supports it...fine. Is he the lone, all knowing, omnipotent expert in the horticultural world? Does that make mrgreen, and myself and the authors of all we've read automatically wrong?

If nitrogen applied at this time actually represented a meaningful threat to winter hardiness of woody perennials cooperative extensions would be pushing back about the dangers with numerous articles documenting winter killed trees and shrubs in landscapes.

They mostly do warn against it harvestman...and I know for a fact that you are aware they do. Why do you think they would publish "numerous" articles about it? It is generally held knowledge by most. They don't publish numerous articles warning against the use of foliar applied glyphosphate on your fruit trees either, but that doesn't mean they are implying it's a good idea. And YES...they DO caution against lawn fertilization near fruit trees late season...you also know that too.

As I said, the research I linked you to I found in a minute search- I'm sure I could find a lot more but am waiting for you to do some homework to back up your opinion instead of simply stubbornly holding on to an old horticultural myth because it makes sense to you.

Nice harvestman. I like the condescending tone here. YES...it makes sense to me, probably because I'm not nearly as smart as you...happy?
Keep on waiting for the homework. I'm not going to go citing sources from multiple authors supporting "my position" because I know that you've already read them along with nearly everyone else here.
And for the Final time, I'm not saying your wrong. I'm simply pushing back against your notion that mrgreen was wrong. Mrgreen could easily cite more sources supporting his original claim than you could in denying it. That is a indisputable FACT. You may not agree with those sources, but so far you've provided nothing concrete to the contrary.

One final thing and them I'm done with this. If fall fertilization provides no risk of winter injury , why then are we only talking about foliar N applications? WHY?
I suspect it's because it is generally held that it COULD cause injury, so foliar applications allow for a shorter N bump, without longer persisting fertilization that may hold trees vegetative into damaging cold periods...just like mrgreen initially said. Kind of "cheating in" a quick shot of N before winter comes.

Everything I've ever read recommended ground applied balanced fertilizer applications broadcast out to the drip line in the spring based on tree age and caliper.
I have seen, as you mentioned previously, K ground applications. I've also seen recommendations for ground applied P applications in the fall in severe drought years because often upper surface feeder roots are sometimes killed in severe drought.
I've never seen general suggestions for fall N applications, though I do not doubt for a second that they are out there.

Do you remember harvestman the split bark photos I posted a few months ago? I applied P late fall (0-48-0 triple superphosphate) and I think I did also foolishly apply a bit of N, which would have been in the form of lawn fertilizer with a N of around 28 or so. I still think that may have been the cause of the bark splitting, although others had similar damage (though not nearly as extensive) apparently without fertilization, so I don't know.

Here's another piece.

Here is a link that might be useful: more on late summer and fall application of N

Appleseed, what are you talking about- how is the Smiley Sharizi study not about the affect of fall N application's affect on winter hardiness- that is the title of the study?

How is the recommended September application of N to cherry leaves not a strong suggestion that it is not a problem in terms of affecting winter hardiness? This is not something that would be overlooked before it is recommended in a state with real winters. And it has been widely recommended.

I did my years in hort school and have long known that the idea of late summer N is harmful to the process of hardening off was pretty much debunked. I thought a single study published by the International Society of Arborists that
corroborates this would at least spur you on to search for other research that might contradict it.

I am very intent on trying to stop people from passing on old and rejected horticultural myths on this forum. There are so many of them and they are hard to kill.

But if you think I'm wrong, show me the data. There's nothing I like better than being PROVEN wrong. In this case, I mean being wrong about there being any research at all that contradicts my position on this issue. Please at least try to find it.

As far as my being condescending- If I was you, I wouldn't bother trying to guess my exact attitude based on e-mail communication. This isn't about you- I'm just trying to get facts straight.

If it was about you I think you seem quite likeable, enthusiastic and bright, but you need a bit more experience before you will reach your potential of separating the ail from the foam.

make that ale from the foam. I blame the ale.

and another

Here is a link that might be useful: best time to fetilize shrubs

Harvestman...the results of this study is pretty much exactly what I expected...it's the egg study all over again...this is just part #1. What IS absolutely astonishing is the EXTREMELY small sample sizes. 12 control shoots...12 w/urea foliar applications just 1 location. I'll get back to methods shortly.

1) In sweet cherry, the effect of fall foliar urea applications on plant susceptibility to freezing injury is unknown.

2) Little is know about the physiological relationship between nutrients and perennial plant cold tolerance mechanisms; practices that stimulate prolonged shoot growth in late summer such as soil-applied N can increase tissue susceptibility to damage by low temperatures in fall or winter. (wonder where the runoff from the foliar application goes ? root zone?..sprayed to runoff)

Study conclusions: Well after a lot of chatter about N storage and how fruiting spur dry weight N content rose 150% (not due to the N application mind you...that was a 40% increase...just due to natural spring processes) they seem unsure of it's overall effect due to uncertainties of it's spring remobilization. Ok...fantastic...moving on.

Experiment #4 was to determine urea foliar applications effect on winter hardiness...now things start getting a little dodgy at this point, and I think that's no accident. They would love some awesome numbers to post...right? Well, unless someone here can explicitly detail the LT50 Spearman-Karber formula I'll just have to take their word for it. So what is the word you ask?...well....uhhhmmm...I'm not sure. I know they claim a 4.25C increase in winter hardiness in their best test, but what does that mean? Well, again it's a number arrived at by the aforementioned formula.
I think more important is the method by which this test is conducted. To make a long story short they take 12 shoots, slice them up with a razor blade, fix the slices to a piece of tape and pop them in the deep freeze at specific temperatures. When removed and thawed they guesstimate the amount of browning (indicating damaged tissue they say) and then insert that number into the formula. 12 shoots sprayed...12 shoots control. What that number means is anyone's guess, but it must not mean what I thought it did.
I just wanted the laymans (rubber meets the road) version and what I took from it was this: Conclusions:

1) Further study of the physiology of N remobilization/metabolism and its potential relationship to cold acclimation in perennial fruit trees is warranted
(this folks is the golden parachute "out plan" statement and can be viewed as nothing other than that)

2) This impact of N reserve levels on cold-hardiness of sweet cherries also should be examined during winter and spring to determine whether they might enhance resistance to incidents like extremely low temperatures during the midwinter and/or during early spring frosts (what?...wasn't that what this study PROVED?) Maybe I get what they're saying here, but it also sounds like more "iffy" speak

3). Whether our reported effects on shoot cold-hardiness also extend to flower buds remains to be determined

4) At this point of investigation, the potential mechanism for the effect of fall foliar N on cold-hardiness is not known; it may be speculated that this process involves a physiological interaction between suitable temperatures for induction of cold acclimation genes and specific amino forms of N synthesized in the leaves on uptake or as translocated to the localized sites of cold acclimation gene activity, but this or other appropriate hypotheses remain to be elucidated experimentally

5) What they really like to talk about is the increased nitrogen content. I don't doubt this a bit and is something they can confidently measure, but are far less confident in their assertions of increased winter hardiness and seem to be very mindful of potential for winter injury as a result.

They did find more and larger leaves in the spring (probably true and I'm confident they can measure this accurately enough), as for everything else...it's sketchy at best. They also found that later applications resulted in a far lower LT50 number than those sprayed earlier. Precisely as I would have (and did) predict. I don't even have a Phd in Economics either...just kinda guessed based on observation...just like folks have for centuries. That would have been before sticky tape, freezers, Spearman and Karber and taxpayer money to conduct tests of little value.

Almost forgot. This study is about sweet cherries and nothing else. Only cherries were studied and evaluated and from what I understand the cold hardiness of apples, pears etc remains unknown. The discussion was indeed began about cherries so the study is pertinent to the thread. I simply want to emphasize that this doesn't apply for everything and they even say so:

Other deciduous trees, like apples (Malus domestica Borkh.), also are dependent primarily on storage reserves for spur leaf formation; however, because apple spur leaves begin expanding before anthesis (thus establishing an evapotranspirational flow within the tree), N uptake by roots begins at approximately full bloom (Neilsen et al., 1997). Consequently, from bloom to fruit set or early fruit development, apple fruit draw on N sources from both reserves and root uptake, whereas cherries draw primarily on N reserves during this period. The fruit development period in apple also is longer than in cherry, meaning a greater proportion of fruit development occurs during active current-season carbon and N uptake.

BTW Harvestman...what they are saying here makes complete sense to me, and yes I do realize there is potential for improved growth from spur storage of N here as well, but it's impact is likely far less particularly in regards to fruit development and wasn't studied at all. Probably for that reason, wouldn't you agree?

The point I'm making is that there is no reason to believe that fall fertilization endangers a plants ability to harden off for winter and that it is now standard practice in fruit production and the management of landscapes and that it is more likely to help than hurt a plants chances of survival based on both research and widespread practice.

In commercial fruit production research, there is the follow up of growers using guidelines on thousands and thousands of trees and the suggestions of urea applications in the fall for apples began in the '90s, I believe. It it weakened trees, I expect growers would have noticed by now.

In golf courses and corporate parks that maintain "pristine" turf, N applications have been made in early Sept. for I don't know how long and the managers of these properties are usually highly trained and attuned to current research. Trees and shrubs are a part of these landscapes.

Most decisions we make in life have less certainty of positive outcomes, so people shouldn't be second guessing themselves and fretting over the decision to apply some N in the fall to serve spur leaves. It is a period when gardeners finally have a little extra time, unlike in spring.

I think the reason that this idea of its danger has stuck around so long is that late forming shoots on some species of trees are subject to winter kill so it was assumed that such excess vigor could also make the entire tree more susceptible to winter kill.

I think the reason that this idea of its danger has stuck around so long is that late forming shoots on some species of trees are subject to winter kill so it was assumed that such excess vigor could also make the entire tree more susceptible to winter kill.

I'm glad you mentioned this, because when I think of Fall fertilization, in my mind's eye these dead previously vigorous shoots are exactly what I envision. I've also noted their rapid formation after heavy fertilization (remember, I have a over fertilizing affliction). So what about that?

In golf courses and corporate parks that maintain "pristine" turf, N applications have been made in early Sept. for I don't know how long and the managers of these properties are usually highly trained and attuned to current research. Trees and shrubs are a part of these landscapes.

Those fall fertilizer applications were (until very recently) most heavily weighted towards P and to a lesser degree K, though I know N was involved as well (slower release N). Fall N on lawns does help, but it doesn't help much when compared to spring applications (cost vs. benefit analysis). It all began when Scott's and others wanted to secure a longer market for their products and knew that it would appeal to those "lawn nuts" (I once was one). Contrary to popular opinion the removal of P from lawn fertilizers was one of the best moves our gov't has made and although I'm unsure, I don't even think it is mandated.

So anyway...I'll concede that you have possibly shifted my thinking a bit on the subject, but not entirely. Long term observation by centuries of intelligent men is hard to overcome. Greater things were accomplished in many disciplines by thoughtful, ingenious, hard working people of antiquity using the power of observation and thought than that of any university research. It always amuses me when all these "smart" folks with strings of letters following their names struggle to figure out something that men knew and fully understood centuries ago. Armed with computers and the latest technology using formulas like the one in this study they just can't "get it". Being a history buff I could give you dozens of examples of this.
Don't misunderstand me, I'm not opposed to research, I'm not. I just think research is often recklessly funded and there is the inclination to achieve results that may secure additional future funding may taint the learning process. I'll bet it happens more than we think. Peer review is carried out by folks with the same inclinations.

Again...what about the winter killed shoots? Surely you've seen their formation after fertilizing? What harm might that dead wood pose in the spring? I've noticed a lot of die-back of vigorous shoots on my peach after winter and to a lesser degree on apples.

What would the cost benefit analysis look like for fall fertilization...what were they using...7 lbs. to 20 gals? How would the N uptake and corresponding growth compare to that same amount applied during active growth periods? We can deduce from this studies own results that foliar application N uptake would in all likelihood be monumentally greater in the spring since later fall applications resulted in less than 1/4 the N uptake as compared to earlier sprays (T1).
I checked on the cost of urea 46-0-0 water soluble fertilizer and it comes in around $50 for 50 lbs....far more for smaller quantities. Cheaper than I thought for sure. I just cannot get over the 7 lbs. to 20 gals (maybe I'm remembering that wrong)...that would be like 11.5 lbs. of miracle gro lawn fertilizer. That amount would fertilize two football fields. Incredible.