Part I, Concepts and Practices of Crop Rotation 1. Crop rotations disrupt cycles of weed, insect, and disease pests. The disruption of weed, insect and disease cycles is a well-known benefit of crop rotations. Rotating vegetables to avoid disease buildup is probably the most widely emphasized use of crop rotation in vegetable production.
Many diseases build up in the soil when the same crop is grown in the same field year after year.
Rotation can help break this cycle. To be effective, rotations must be carefully planned. Since diseases usually attack plants related to each other, it is helpful to group vegetable rotations by family e.g., nightshades, alliums, cole crops, cucurbits. The susceptible crop, related plants, and alternate host plants for the disease must be kept out of the field during the rotation period. Plant diseases persist in the soil for different lengths of time, so the length of the rotation will vary with the disease being managed.