Yes Michael orchardists do this.

I was reading an article in a hort magazine from 1907 that mentioned spraying sodium nitrate to improve the set of red apples.

It is also done to help break down leaves so they dont carry disease over to next season.

I have done the same spray (urea) on plums to knock the leaves off.

I had to use very high rates to get a result.
In the end (after some weaker sprays) I used 8kg / 100litres of water.
Even then it did not take all the leaves of.
In fact there were crystals of urea on some leaves and they still didn't fall.
I sprayed mid autumn, it was still a bit warm but not hot.
Dates are of no use here because we are in different hemispheres.

The trees sprayed with the urea came in to blossom earlier the next year and the blossom was tight (not spread over a long time)

The urea does do something to help break dormancy in tree crops.
Using Potassium Nitrate autumn sprays is also used by fruit growers

Not sure if this is usefull but if you cant get the leaves off.. the umass guy puts down a food grade urea spray to decompose leaves in late winter early spring.

Here is a link that might be useful: saving scab sprays with urea

Thanks Mike and Joe: I think I'll do a test run of dissolving fertilizer grade urea in water first. Hopefully our local elevator has feed grade urea. I can also get liquid URAN (urea ammonium nitrate) 28-0-0 or 32-0-0 from them but who knows what the rate would be for that.

does anyone else have any evidence of earlier bloom caused by fall applied foliar N applications?

Michael

Not sure why anyone but a commercial grower would bother doing this but it's very interesting. I'd think it would be more efficient for reducing fungus innoculum just to blow or rake the leaves in the fall and compost them some distance from the orchard. What is the advantage of knocking off leaves early? They are returning N and other nutrients to the leaf buds until they drop. You can get extra N to the buds by a ground application in early fall.

What is the advantage of increased N in the buds? Does it make them more attractive to bees or something? I have heard of a few people fall applying fertilizer through the soil down here for the purpose of upping N in the buds but I never understood why.

Thanks,
Scape

It leads to larger spur leaves and then larger fruit. It increases fruit size by increasing the number of cells as opposed to increasing the size of the cells which later N might be more prone to doing. I believe the former may lead to higher brix than size increase based on larger cells. Any comments from you commercial growers out there? I'm confident of the first sentence but half of the rest is presumption.

Thanks all for the posts: H-man, it is more a need to get the leaves off period. Freedom seems to hold on to a minority of it's leaves up till the time it is time to start spraying in the spring. Two or three of my 2nd leaf trees had their leaves removed by hand in March, maybe they are a new class I'll call semi-deciduous or maybe spring deciduous. Untill I started growing apples I never knew a deciduous tree could hang onto leaves until spring. Another lesson.

Michael

And what is the harm of these leaves hanging on to the tree? I am even more curious of why they are holding on. I have Freedom in my nursery and I didn't notice leaves lasting deep into winter. I'll take a closer look this winter.

Thanks for the info Harvestman. That is really great info to know. Due to our massive drought and heat wave the last few years fruit size has been really small and I look forward to getting any tips on how to size them better. On another note, Michael 357 I think I may know why your leaves are not comming off. I have heard from many people that this is a common occurence on a juvenile tree. Based on your last post it sounds like these are 2nd leaf trees. Especially if your trees are on a vigoruos rootstock I think this may account for the leaves lasting so long. I'll bet after another year or so they will calm down and drop on time. I also second Harvestmans notion that this may not be a problem at all. Down here a lot of young apples dont ever lose there leaves. The new flowers and leaves push the old ones off and they still crop as they should. This is just my guess.

Thanks,
Scape

For me, it's a little more than a guess. I have observed that tips that grow into winter do not delay the hardening off of the rest of the tree. I can't say this is always the case but for apples I believe it pretty much is.

I have to assume it is the hardening off you are worried about.

I'd say my biggest concern with the leaves hanging on is the inoculum they may be harboring. If I chose to do a late fall app. of Kocide, the leaf scars wouldn't be exposed where leaves were still attached and it would be a tiny bit more work to get thorough coverage. Wether or not the leaf scars would be an issue I can't say.

Frankly, I just want what I want, that is to say all the leaves off at a time convenient to gathering them up, spraying on the ground or incorporating them. I don't imagine having them blowing all over the orchard dropping here and there all winter long is conducive to good sanitation practices. Darned trees, they never behave the way I want them to!!! Guess I'll just throw tantrums and hope they fall off on MY schedule!

For what it is worth, the Freedom tree is in it's 5th leaf, the rest are 1st and 2nd and on M7.

I thought the point of growing Freedom was the lack of the growth of innoculum on the leaves.

Well H-man that's true but of the 10 cvs. I have, it is the only one that doesn't have significant scab susceptibility. There are many other apple trees in my little town so I'll never be able to rest on my laurels as far as fungicide use goes during the spring and assume there is no innoculum around to be concerned about later. Fortunately, PM and FB have not yet been an issue but CAR is heavy enough every year to make up for them all.

I am simply attempting to establish the best cultural practices possible as they are instrumental in disease control as I have no doubt you already know. Taking care of overwintering inoculum is where I am at now.

Who knows, maybe some day all we'll have left is cultural controls, better plant another Freedom or a Williams Pride tree in that case.

Actually, I've not seen research indicating how much sanitary practices actually help remove innoculum, although it's certainly often repeated in literature and seems logical.

Certainly in controlling scab I have not found observable advantage to removing leaves in anecdotal observation and CAR has an alternate host and won't be affected by removing leaves after they drop as I picture the issue.

But you know me, always the contrarian.

H-man: I appreciate the contrarian perspectives as I have been known to practice contrarianism myself. I had a couple of professors in school that used it very effectively for the purpose of getting all of our little minds full of mush to actually think.

Not worried about the CAR laying around as I'd have to remove thousands of Eastern Red Cedars from all the pastures and fence lines that surround me. The pasture owners would be more than happy to have me remove the cedars however. Like I don't have better things to do.

All those years in greenhouse production really beat the sanitation idea into my head and to a lesser extent, vegetable crop research. My greenhouse bosses would blow a head gasket if they saw anyone leave a hose end on the ground. If I can do things to avoid a spray or mitigate a current or subsequent problem, why not as long as it makes sense.

Michael

Which I agree is perfectly reasonable, for whatever that's worth.