Left to their own devices, apple trees would pollinate, or “set”, three or four times as many apples as they need. And they would all be about the size of a 50-cent piece. (That’s one of the reasons that very few people bother with wild apples.)
Of course, the tree’s only goal is to reproduce itself in the tiny seeds in its developing core. But the apple grower’s goal is to get an apple large enough that people will want to eat them. So how do we make that happen?
The process is called “thinning,” which literally means reducing the number of pollinated blossoms on a branch so the tree is not overloaded and we get fewer, but larger, apples.
In most varieties, the tree will thin itself – a little bit. That process is called June drop, and it’s when the poorly-pollinated, deformed and excess apples drop off the tree. Problem is, the tree is usually still overloaded.
Commercial apple growers must pull together science, weather, customer expectations and knowledge about their own trees when they decide how many apparently-pollinated blossoms should be culled off each type of apple tree.
Too many, they have no crop for market. Too few, and the apples are too small.
A combination of a natural plant hormone is used to encourage trees to drop more of their apples at about the same time as June drop. There’s horticultural science, and then there’s the art of being a skilled apple grower.