Welcome to Southern living and growing jonagold.  The old original strain will 
never get color this far south. The newer strains will be about like your 
original strains if we are lucky enough to have some cooler nights and sunny 
days.  Cold nights, sunny days AND good pruning will get you color. 

   

 On Thursday, October 13, 2016 12:12 AM, Glen Koehler <glen.koeh...@maine.edu> 
wrote:
 
 

 Hi Art    A contributing factor to problems with fruit color this fall has 
been late arrival of minimum temperatures below 42F,   A "rule of thumb" from a 
Cornell bulletin is that optimum coloring conditions require two days with low 
temperature below 42F, followed by a day with high temperature over 68F AND 
over 80% sunlight on that day.  
     The Ag-Radar estimate for Sanford 9 miles away from you (far enough that I 
wish we had closer data site, working on that) shows that the two days below 
42F requirement was not met until September 26, and Sept. 27 had a high 
temperature over 68F.  But the requirement for a day with high temperature over 
68F AND over 80% sunshine was not met until October 6.
    I don't see this formula as a powerful predictor, esp. since I've seen some 
good color improvement while checking traps and doing fall scab index over the 
past few weeks.   And even if it was a robust predictor, it wasn't based on 
Jonagold.  Still it gives some numbers to possibly help explain late coloring 
conditions this fall.
    Easy to suspect the drought as a contributing factor.  I'm also wondering 
if you used ReTain on these Jonagold.  If so, do you think that had any effect 
on coloring?
- Glen
Glen Koehler
University of Maine Cooperative Extension
Pest Management Office
Voice:  Office 207-581-3882,   Cell  207-485-0918
491 College Avenue, Orono, ME  04473UMaine Apple IPMAg-Radar
On Wed, Oct 12, 2016 at 2:19 PM, kellyorchards <kellyorcha...@gmail.com> wrote:

Why are my Jonagolds not coloring?  Can this be an issue if they have a heavy 
crop?


Art Kelly
Kelly Orchards
Acton, Maine
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