Why an apple tree can respond like this has to do with a character not being learned as a seedling.Such as in a greenhouse and in an artificial lighting situations. HOW? (you may ask).. Plants go beyond years remembering situations. In about plants survival is timing. In turn timing requires memory. Discovery inside plants reveal memory.

Memory in Plants -PRIONS

Splitting a plant up in the first year of life is still pretty much assexual, meaning that both are considered seedlings very much alike each other if done right. Now from that point they can be trained in seperately distinct environments and more adapt to special assignments. With that possibility comes a fixation period and a lack of changing to adapt anymore as they were when young to any further change of circumstances in the environment. For example a greenhoused artificially heated place all year long for the crabapple it might be that every change in weekly averages in temperature from one week to the next should always trigger flowering. This month started cooler then stayed normal. Because plants have memories all over the place I wonder what to expect grafting them together on another normal flowering crabapple and if after second blooming upwards of the graft if any of this advances on the plant psycology of the reast of the plant? I remember many examples debating this kind of mentor effect when I was on a group mailer list with other experts. Mentoring is an old proven method first discovered in Russia research over 100 years ago. The model often works for teaching plants from a long growing season to adjust to short season and cold winters. A very debatable point to find anything on with aquired plant plasticity here in regards to bacterial resistance. For example greenhouse produced trees as young seedlings lack the excercising to there immunity systems to bacterial infection, or not? Is it proper to ask your money back that your tree should have been guaranteed that long. (?) Probably NO. 🙂 And another reason why I support HOS when I can. (many questions.. hmmm)

Enough about that, now helping what looks like another tragedy;
Previously unregarded from other thread:
"I have a cherry tree that dropped all its leaves. Now its budding out again in blossoms. Im from Arizona but, Im pretty sure thats not right. Any ideas on whats going on inside my cherry tree? (8-25-2016)"

My short responses to the out of sync cherry flower production etc. is quite a bit different conclusion than the fore going one in that yours lacks leaves and might be injured or sick. That it is growing in Arizona it could also be a lack of winter chill hours, which in that case it is an inherited timing function, in which ever case will demise the tree eventually because timing is almost everything. In your case of lacking chill the tree material can be collected in the fridge over winter, regrafted where more chill hours occur, problem solved. Probable case of the double flower apple situation with leaves is non reversible.