North American Fruit Explorers mailing list at ibiblio

["Alan Haigh" <alandhaigh@gmail.com>]

Hard to diagnose from afar, but I'll take a stab.  The most vigorous shoots are most vulnerable to freeze damage.  One year after a long drought here we finally got a deluge in late August.  This caused an outburst of late growth, especially for Japanese plums.  A lot of this late growth was winter killed with no visible damage to the rest of the affected tree in appearance or vigor. 

 

At the time this was interesting to me because I had so often read of the dangers of late nitrogen application delaying winter hardening which this event simulated.  The damage was minor and similar events in subsequent seasons but occurring just a couple weeks later didn't even create the vegetative outburst.  I now discard those late application warnings as another example of hort myth (at least until someone shows me some actual research).

 

For you it might be interesting as a possible explanation to your "big question".