[Apple-Crop] Timing of foliar nitrogen in peach

[Jerry Frecon]

>From Roger Duncan, Pomology Farm Advisor, UC Cooperative Extension, Stanislaus County
"Fall can be an excellent time to apply certain nutrients if trees are deficient.
Nitrogen. Nitrogen utilized by trees and vines for early season shoot and fruit growth comes
from reserves stored in the roots and other woody tissues of the plant. This is why it is
important to enter into dormancy with adequate nitrogen reserves. UC Extension pomologist
Scott Johnson has shown that a low biuret urea foliar spray just prior to natural leaf senescence
is an excellent method of supplying nitrogen to peach trees. At least 80% of the nitrogen is
absorbed into the leaf within 24 hours. The nitrogen is then readily translocated out of the leaf
and into long-term storage. Trees low in nitrogen because of nematodes, a high water table or
other root problems should certainly benefit from this spray. This is also an excellent way to
provide nitrogen without risk of ground water contamination.
Each spray supplies about 50 pounds of actual N per acre. That means if a granular
formulation of low biuret urea is used (which is almost 50% N), you need to apply about 100
pounds of product per acre. If a second application is necessary, it should be applied at least
two weeks after the first application. Within a few days, you should start to see some burn
along leaf margins and at the tips. Defoliation will probably progress a little more quickly than
normal."

Urea application on peach in New Jersey have not been observed to be effective in increasing tissue N in leaves buds and shoots. (Much research on this subject in Fruit Nutrition by Childers and others)   If  N tissue levels were  increased as they are with N soil applications then N deficient peach trees may be healthier and more winter hardy,  I am not aware of any research demonstrating a delay in bloom with urea foliar applications.  

Jerome L "Jerry" Frecon
Professor Emeritus, Rutgers University
And Horticultural Consultant for
www:jerseypeaches.com
www.acnursery.com

-----Original Message-----
From: apple-crop [mailto:apple-crop-bounces at virtualorchard.com] On Behalf Of Mark Angermayer
Sent: Sunday, September 10, 2017 1:46 PM
To: apple-crop at virtualorchard.com
Subject: [Apple-Crop] Timing of foliar nitrogen in peach

I've read foliar urea in fall can increase hardiness and delay bloom on peach.

Can anyone tell me the optimum time to apply foliar urea (100 lbs./ac
-  i.e. 50 lbs. actual N) on peach?  I'd like to use regular soil urea (vs. the low biuret) because of cost, but understand soil urea will burn the foliage.

I don't want to apply it too early so as to minimize photosynthesis from premature leaf drop, but don't want to apply it too late so the leaves won't absorb the N.

U of C says to apply it in Sept. or Oct. (not Nov.) but the climate out there is quite a bit different than here.

Anyone have a good general guideline to go by (i.e. just before leaf drop, two weeks before leaf drop, etc.)?

http://ucanr.edu/sites/fruitreport/Nutrition_-_Fertilization/Individual_Nutrients/Nitrogen/Foliar_Urea/

http://ucanr.edu/sites/fruitreport/files/162635.pdf

Thanks,
Mark Angermayer
Tubby Fruits Peach Orchard
KS/MO
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