There are several rootstocks that we are doing experiment on them such as Gi3,5,12, Cass, Clinton,…

late summer pruning encourages the tree to form fruiting spurs. In most of the US and Canada, that would be mid-late august. essentially, stub all new growth back to 2-3 buds at that time. Summer pruning also allows you to keep your rows narrow by hedging the trees (mine are 7 feet on center)

В одном комменте я прочла, что уже давно так формируют деревья в Мореуполе и даже ветки не подвязывают. В плане обрезки очень хорошая формировка.

Какие сорта пригодны для такой форсировки

having a double cordon alllows you to use more vigorous rootstocks and place the trees further apart. What has been found is that once the cordon gets much longer than 4 ft, there is not enough energy getting to the end (due to apical dominance) to have decent growth and fruit. Growing a double cordon allows you to fill a 7-8 ft space (rather than 3-4ft) with good vigor and fruit loads. You're talking the difference between 888 trees/ac (planting 7x7), and 2070 trees per acre (planting 3x7). Less trees makes if more affordable to establish (even though the tighter spacing will have higher yields the first 2 fruiting leafs). Also, on a practical side, most nurseries head the whips they sell, so they can fit in the shipping containers, so just allowing the tree to branch and selecting two cordons makes sense unless you have a nursery that is able to accommodate an un-headed whip (or you are growing your own trees).

we have used Benton grafted on some sweet cherry rootstocks such as Gisela3, 5,12, Clinton, Cass, Clare, Lake, ...