This year, as fruit trees in general and apple trees in particular rebounded spectacularly from 2012's abysmal growing conditions, some of them haven't. Carl Burhop of Green Street Tree Care says the company has received "half a dozen or so" calls for help this year from residents with collapsing apple trees. How often does that happen in a typical season? "Rarely," says Burhop. "Last year was zero."
Even if they aren't falling down, "I've been looking at a lot of trees that are under stress because they're so laden with fruit," he says, "mostly apples, because they have the biggest, heaviest fruit."
A couple of crabapple trees have broken in Nichols Arboretum, too, says Tom O'Dell, a horticulturist there and at Matthaei Botanical Gardens, "but what contributes to that is rainfall. If you have a heavily fruited branch and add the weight of rainwater to that branch, that may be all it takes to break it."
The late-winter heat wave of 2012, followed by a killing spring frost and dry summer, devastated the yield but left the trees with plenty of leftover energy and nutrients that they poured into this year's crop. "They don't have a brain, but somehow they know they didn't have many fruits last year," says Mike Palmer, a colleague of O'Dell's. "Also, the plant needs to procreate. If we're going into a five-year drought, it wants to produce as many seeds as possible, not to keep itself alive but for the species to survive."