Late-season "Rescue" Thinning with Ethephon
We all experience occasional failures during the normal apple thinning period from petal fall through the 12mm stage. Once fruit are larger than 12 mm, there are very few options for fruitlet removal. The most commonly utilized technique in New England is hand thinning. Hand thinning is usually performed in early July. Because of this timing, it has very little effect on return bloom the following year, since most flowerbud formation occurs in June. So, it may be possible to gain some fruit size with hand thinning, but if the set is heavy before hand thinning, bloom may be light the next year and trees may even become biennial.