When the apple trees are pumped full of nitrogen and water to make the apples big and keep them from burning when they can’t get cool in the summer sun, then some global warming is needed in late August and early September.
This is done with clippers, to expose all the apples to as much sun as possible in the effort to get them to colour up (and sweeten up) before picking. It’s a delicate dance. The sun and cold nights will colour up the apples, given time (and cold, especially.) At the same time, though, the starch in the apples is going to be converted to sugar in order to keep the apples alive and well. That’s all a normal process, but without the leaves to create new starch and sugar, which migrates around the tree to where concentrations are low, there’s hardly enough to go around. This technique forces what starch there is in the apples to turn to sugar, without being particularly diluted by water or new starches, and then, eventually, having richer sugars. At the same time, most of the starch-producing leaves are gone, so it’s just not possible anymore. That’s the trick.. Timing has to be perfect to play this game. In the end, you will likely get red apples but their flavour and juiciness will never be particularly high. You’ve forced them to mature early, with fewer resources. It would be better to have a training system that worked with a tree’s natural tendencies, but those don’t fit popular industrial models, and apples are graded by colour, not taste, in a 100+-year-old grading system that presupposes that a red apple is one that has grown in full sun, with the full support of a tree. Humans have learned to cheat by forcing the trees into a secondary process. Sadly, the apples are not first rate.
However, if these trees were trained to grow naturally, the apples would burn mid-summer. All those leaves make for good global cooling, which, ironically, must then be cut away. It’s simply not the best training method for this variety, and not the best root for it, either, but it’s the way of it these days. If you wonder why those Royal Galas just don’t taste up to snuff, well, perhaps now you know one reason why.