Commercial apple cultivation has changed dramatically since the 1970s, as it has for most fruit trees. In contrast to the large-canopy, high-stemmed labour intensive trees that were dominant until then, commercial cultivation today uses only the low-stemmed form. Thus,10 to 20 times more trees can be grown in the same area. Their height is limited so that all work can be done by hand without a ladder. Cherries for the processing industry are often harvested mechanically. In the mid-nineteenth century about 2000 varieties of apples were known, while today there are only 20-30 varieties of economic importance.