Original: Varieties of crabapple are selected to bloom contemporaneously with the apple variety in an orchard planting, and the crabs are planted every sixth or seventh tree, or limbs of a crab tree are grafted onto some of the apple trees.
Simplified: Varieties of crab apple are selected to bloom at the same time as the apple trees in an orchard, and the crabs are planted every sixth or seventh tree, or limbs of a crab tree are grafted onto some of the apple trees.