To keep deciduous fruit trees to an easily pickable height, pruning in Summer is recommended. Now is the perfect time for the first round of Summer pruning (with a second round in February). Take a pair of shears and trim off half of the new growth. You will see the new growth has green bark, compared to the brown bark from the previous season.
Training branches from being very upright growing to more horizontal is an excellent way to encourage fruit production and reduce vigorous growth. Tie branches down while they are young and supple using soft string or weights.
Here is a 14 year old plum tree (Santa Rosa variety) which has been turned into a fruit bush with regular summer pruning.
Photo Credit: Dave Wilson Nursery