June drop and fruit set

After petal fall the tree carries a large number of fruitlets, several per flower cluster. They compete with each other and with shoot growth for carbohydrate, and the tree resolves the competition by shedding. Abscission layers form at the base of the weakest fruitlets and they drop, usually over a couple of weeks in late spring or early summer — June in a northern maritime climate, which is where the name comes from.

Seed content is the main determinant of which fruitlets survive. Developing seeds are hormone factories, and the gibberellins and auxins they export are what suppress abscission and draw resources to the fruit. A fruitlet that was poorly pollinated, and therefore carries few seeds, exports weaker signals and loses the competition. This is why poor pollination shows up as a heavy June drop rather than as a failure to set at all.

Growing conditions modulate the severity. A dull, cool spell around June drop reduces photosynthesis, sharpens the competition and increases the shed; a bright warm spell reduces it. A heavy drop after a good bloom therefore does not necessarily indicate a problem, and a light drop is not necessarily good news, since the tree may be carrying a crop it cannot ripen properly.

Not every early fruit fall is June drop. Fruitlets dropping immediately after petal fall, before they have grown at all, usually indicate failed fertilisation — a frost during blossom, cold weather that stopped pollinators flying, or a variety with no compatible partner in flower. The tell is the timing and the size: unfertilised fruitlets stay tiny and yellow before dropping.

Pest damage produces its own drop. Apple sawfly larvae tunnel into young fruitlets and cause them to fall in early summer with a characteristic ribbon scar or exit hole and wet frass; codling moth causes a later drop with a tunnel to the core. A drop with holes in it is not June drop.

The practical response in a cider orchard is generally to observe rather than to act. There is no economic intervention available after the event, and the information is worth more for next year than this one: a severe early drop across a whole block points at a pollination problem to fix by grafting or interplanting, not at anything that can be corrected in the current season.

Dessert growers thin deliberately, by hand or chemically, because fruit size determines price and because moderating crop load prevents biennial bearing. Neither incentive applies with the same force in a cider orchard: fruit size is irrelevant to a press, and the cost of thinning several hundred trees per hectare cannot be recovered from fruit sold by the tonne.

The consequence is that cider trees are routinely allowed to overcrop, and overcropping is precisely what triggers biennial bearing. A cider orchard therefore lives with a swing between heavy and light years that a dessert orchard manages away. Whole districts crop in phase with each other, mills receive far more fruit in one year than the next, and single-variety cider from a biennial cultivar is not available every season.

Where thinning does happen in cider growing it is usually on high-value fruit for single-variety production, or in young trees where letting a light crop develop protects the framework. Both are exceptions justified by something other than tonnage.