Corn - often successful, but raises risk of head scab since corn is a reservoir for scab fungus. If wheat is grown continuously, residue management can be beneficial particularly where tan spot and take-all are problems. Moldboard plowing is not recommended because of soil erosion concerns but light tillage can increase residue contact with the soil and hasten the demise of pests lurking in the residue while leaving soil cover. Volunteer wheat is a reservoir of wheat streak mosaic and wheat curl mites and if left undisturbed, the mites will carry the virus to newly-emerging fields in the fall. All volunteer wheat within one-half mile should be destroyed at least two weeks before planting.
Excess nitrogen produces a lush canopy that favors powdery mildew and strawbreaker foot rot.
Make sure chloride is not limiting. Chloride deficiency has been linked to increased foliar diseases. Combine liming with crop rotation where possible. Liming favors take-all root rot. Although no variety is resistant to everything, modern varieties have much better resistance to diseases and insects than those from a decade ago.