Controlling Wheat Diseases in Direct Seeding Systems Controlling Wheat Diseases in Direct Seeding Systems Adapted from Agdex 519-9. Revised May 1999. Weather conditions and crop rotations are much more important factors than the amount of tillage in determining disease occurrence and intensity. Dwarf bunt occurs in eastern Canada and the inter-mountain valleys of southern British Columbia. Karnal bunt is widespread in the southern U.S. and severly affects the movement of cereals from the U.S. to Canada.
Stripe rust occurs sporadically on winter and irrigated wheats.
Herbicide injury can sometimes resemble infectious diseases. It can significantly harm crop growth and production and may increase disease susceptibility. Herbicide injury can result from herbicides applied to the crop or from herbicide residues. Severe herbicide injury from aerially applied herbicides in wheat crops may result from an interaction of one or more factors including high crop residue levels, high manure application rates, high soil moisture, soil-borne herbicide residues and soil copper deficiency. A deficiency of micronutrients such as copper is a widespread problem and significantly limits yields in an estimated 10 per cent or more of Alberta cropland.