What is crop rotation?

Crop rotation is one of the oldest and most effective cultural control strategies. Growing a single crop year after year in the same field gives pest populations sufficient time to become established and build up to damaging levels. Rotating the field to a different type of crop can break this cycle by starving pests that cannot adapt to a different host plant. Farmers in the Midwest, for example, can reduce populations of wireworms (Elateridae) and rootworms (Diabrotica spp.) in corn fields by switching to oats, wheat, or legumes. Similarly, the clover root curculio (Sitona hispidula) that feeds exclusively on legumes can be eliminated by switching from clover or alfalfa to corn or small grains. Rotation schemes have also proven successful for controlling pests in pasture lands. Texas cattle fever, a protozoan disease transmitted by cattle ticks, Boophilus annulatus, has been eliminated from the southern United States due, in part, to a diligent campaign of pasture rotation designed to protect beef and dairy herds from tick infestation.
Crop rotation schemes work because they increase the diversity of a pest's environment and create discontinuity in its food supply. As a rule, rotations are most likely to be practical and effective when they are used against pests that:
attack annual or biennial crops
have a relatively narrow host range
cannot move easily from one field to another, and
are present before the crop is planted