As today is July 1, we can be hopeful that our intrepid quince has survived June Drop; technically, it could still happen, but why dwell on unpleasant possibilities?
In the cooler and wetter Spring pollination season, fruit trees tend to pollinate and set a large number of fruits. As the year progresses and we enter the drier and considerably warmer early Summer months, the trees end up burdened with more fruit than they can handle and they start shedding — dropping — the excess. We walk outside one morning and find the ground littered with half-developed fruit. I know to expect it, but I still find it alarming.
Living plants create energy in the form of sugars and carbohydrates through the process of photosynthesis. Of the many ways we can consider the parts of any plant, one way is to consider the various parts as being in one of two categories: those parts that create energy, and those parts that use energy. Fruits definitely fall into the latter category; fruits are energy sinks, and draw a huge portion of energy from a plant. If a fruit tree has more energy users — fruits — than it can support with its energy producers — leaves and such — then it begins shedding the unsupportable extras; some are sacrificed so that the available energy can go to the survivors.
It's a little bit like when you're running the toaster and the coffee pot and the waffle iron and the stand mixer and the light above the sink all at the same time and the circuit blows. Not quite the same, of course: we don't have to sacrifice the waffle iron for the greater good of the toaster; we just re-set the circuit breaker.
When you see June Drop, don't panic; do be certain that the tree has adequate but not excessive water; and throw the falls on your compost pile, where they will still be of some utility.